February 2, 1996
This section provides a detailed description of each node in VRML 2.0. It is organized by functional group. Nodes within each group are listed alphabetically. (An alphabetical Index of Nodes and Fields is also available.)
Intrinsic nodes are nodes whose functionality cannot be duplicated by any combination of other nodes; they form the core functionality of VRML. The functional groups used in this section are as follows:
These nodes provide common functionality that all VRML implementations are required to support, but that can be created using one or more of the intrinsic nodes. A reference PROTO implementation is given for these nodes (note: we didn't have time before the VRML 2.0 RFP to do all implementations, for several nodes we just sketch out what the PROTO would look like).
The last item in each node description is the public interface for the node, with default values. (The syntax for the public interface is the same as that for prototypes.) For example:
DirectionalLight {
exposedField SFBool on TRUE
exposedField SFFloat intensity 1
exposedField SFFloat ambientIntensity 0
exposedField SFColor color 1 1 1
exposedField SFVec3f direction 0 0 -1
}
Fields that have associated implicit set_ and _changed events are labeled exposedField. For example, the on field has a set_on input event and an on_changed output event. Exposed fields may be connected using ROUTE statements, and may be read and/or written by Script nodes.
Note that this information is arranged in a slightly different manner in the file format for each node. The keywords "field" or "exposedField" and the types of the fields are not specified when instantiating a node in the file format. For example the file format for the above example is:
DirectionalLight {
on TRUE
intensity 1
ambientIntensity 0
color 1 1 1
direction 0 0 -1
}
Grouping nodes can contain other grouping nodes or leaf nodes as children. Grouping nodes include the Collision and Transform nodes.
The children of a grouping node are specified using an MFNode field.
The Collision grouping node specifies to a browser what objects in the scene should not be navigated through. It is useful to keep viewers from walking through walls in a building, for instance. Collision response is browser-defined. For example, when the user comes sufficiently close to an object to register as a collision, the browser may have the user bounce off the object or simply come to a stop.
The children of a Collision node are always drawn, just as the children of a simple Group are drawn. These children are the objects that are checked for collision. If desired, a proxy object can be supplied, and this proxy object will be checked for collision in place of the actual child objects (see description of the proxy field, below).
By default, collision detection is ON. The collide field in this node allows collision detection to be turned off, in which case the children of the Collision node will not be checked for collision, even though they will be drawn.
Since collision with arbitrarily complex geometry is computationally expensive, one method of increasing efficiency is to be able to define an alternate geometry that could serve as a proxy for colliding against. This collision proxy, contained in the proxy field, could be as crude as a simple bounding box or bounding sphere, or could be more sophisticated (for example, the convex hull of a polyhedron).
If the value of the collide field is FALSE, then no collision is performed with the affected geometry. If the value of the collide field is TRUE, then the proxy field defines the geometry against which collision testing is done. If the proxy value is NULL, the children of the collision node are collided against. If the proxy value is not NULL, then it contains the geometry that is used in collision computations.
If children is empty, collide is TRUE and a proxy is specified then collision detection is done against the proxy but nothing is displayed-- this is a way of colliding against "invisible" geometry.
The collision eventOut will generate an event containing the time when the path of the user through the scene intersected a geometry in this collision node against which collisions are being checked. An ideal implementation would compute the exact moment of intersection, but implementations may approximate the ideal by sampling the positions of geometries and the viewer.
Collision {
exposedField SFBool collide TRUE
field SFNode proxy NULL
exposedField MFNode children []
eventOut SFTime collision
}
A Transform is a grouping node that defines a coordinate system for its children that is relative to the coordinate systems of its parents. A Transform's children can include any grouping or leaf nodes: lights, viewpoints, sounds, shapes, and browser information nodes. See also "Coordinate Systems and Transformations."
The bboxCenter and bboxSize fields may be used to specify a maximum possible bounding box for the objects inside this Transform. These are hints to the browser that it may use to optimize certain operations such as determining whether or not the Transform needs to be drawn. If the specified bounding box is smaller than the true bounding box of the Transform, results are undefined. The bounding box should be large enough to completely contain the effects of all sounds, lights and fog nodes that are children of this Transform. If the size of this Transform may change over time because its children are animating (moving), then the bounding box must also be large enough to contain all possible animations (movements).
The add_children event adds the nodes passed in to the Transform's children field. Any nodes passed in the add_children event that are already in the Transform's children list are simply ignored. The remove_children event removes the nodes passed in from the Transform's children field. Any nodes passed in the remove_children event that are not in the Transform's children list are simply ignored.
The translation, rotation, scale, scaleOrientation and center fields define a geometric 3D transformation consisting of (in order) a (possibly) non-uniform scale about an arbitrary point, a rotation about an arbitrary point and axis, and a translation. The Transform node:
Transform {
translation T1
rotation R1
scaleFactor S
scaleOrientation R2
center T2
...
}
is equivalent to the nested sequence of:
Transform { translation T1
Transform { translation T2
Transform { rotation R1
Transform { rotation R2
Transform { scaleFactor S
Transform { rotation -R2
Transform { translation -T2
...
}}}}}}}
Transform {
field SFVec3f bboxCenter 0 0 0
field SFVec3f bboxSize 0 0 0
exposedField SFVec3f translation 0 0 0
exposedField SFRotation rotation 0 0 1 0
exposedField SFFloat scale 1 1 1
exposedField SFRotation scaleOrientation 0 0 1 0
exposedField SFVec3f center 0 0 0
exposedField MFNode children [ ]
eventIn MFNode add_children
eventIn MFNode remove_children
}
This section describes the leaf nodes in detail and is organized into the following subsections:
This functional group includes the Viewpoint node.
The Viewpoint node defines an interesting location in a local coordinate system from which the user might wish to view the scene. Viewpoints may be animated, and Script nodes may "bind" the user to a particular viewpoint using Script API calls to the browser. A world creator can automatically move the user's view through the world by binding the user to a viewpoint and then animating that viewpoint.
The position and orientation fields of the Viewpoint node specify relative locations in the local coordinate system. Position is relative to the coordinate system's origin (0,0,0), while orientation specifies a rotation relative to the default orientation; the default orientation has the user looking down the -Z axis with +X to the right and +Y straight up. Note that the single orientation rotation (which is a rotation about an arbitrary axis) is sufficient to completely specify any combination of view direction and "up" vector.
The fieldOfView field specifies a preferred field of view from this viewpoint, in radians. A smaller field of view corresponds to a telephoto lens on a camera; a larger field of view corresponds to a wide-angle lens on a camera. The field of view should be greater than zero and smaller than PI; the default value corresponds to a 45 degree field of view. fieldOfView is a hint to the browser and may be ignored.
A viewpoint can be placed in a VRML world to specify the initial location of the viewer when that world is entered. Browsers should recognize the URL syntax "..../scene.wrl#ViewpointName" as specifying that the user's initial view when entering the "scene.wrl" world should be the first viewpoint in file "scene.wrl" that appears as "DEF ViewpointName Viewpoint { ... }".
The description field of the viewpoint may be used by browsers that provide a way for users to travel between viewpoints. The description should be kept brief, since browsers will typically display lists of viewpoints as entries in a pull-down menu, etc.
Viewpoint {
exposedField SFVec3f position 0 0 0
exposedField SFRotation orientation 0 0 1 0
exposedField SFFloat fieldOfView 0.785398
field SFString description ""
}
This grouping includes nodes that light the scene (DirectionalLight, PointLight, and SpotLight) as well as nodes that affect the lighting within the scene, such as the Fog node.
Lighting is additive, so objects are illuminated by the sum of all of the direct and ambient illumination impinging upon them. Ambient illumination results from scattering and reflection of direct illumination, so logically ambient light is tied to lights in the scene, with each having an ambientIntensity. The contribution of a light to the overall ambient lighting is computed as ambientLight[i] = on ? (intensity * ambientIntensity * color[i]) : 0, i=0,1,2. This allows the light's overall brightness, both direct and ambient, to be controlled by changing the intensity. Renderers that do not support per-light ambient illumination may simply use this information to set the ambient lighting parameters when the world is loaded.
The DirectionalLight node defines a directional light source that illuminates along rays parallel to a given 3-dimensional vector.
A directional light source illuminates only the objects in its enclosing Group. The light illuminates everything within this coordinate system, including the objects that precede it in the scene graph--for example:
Transform {
children [
Shape { ... },
DirectionalLight { .... } # lights the preceding shape
]
}
Some low-end renderers do not support the concept of per-object lighting. This means that placing DirectionalLights inside local coordinate systems, which implies lighting only the objects beneath the Transform with that light, is not supported in all systems. For the broadest compatibility, lights should be placed at outermost scope.
DirectionalLight {
exposedField SFBool on TRUE
exposedField SFFloat intensity 1
exposedField SFFloat ambientIntensity 0
exposedField SFColor color 1 1 1
exposedField SFVec3f direction 0 0 -1
}
The Fog node defines an axis-aligned ellipsoid of dense, colored atmosphere. The size field defines the size of this foggy region in the local coordinate system. The maxVisibility field specifies the distance at which an object is completely obscured by the fog. This distance is specified in the local coordinate system (by default, in meters). The color field may be used to simulate different kinds of atmospheric effects by changing the fog's color.
An ideal implementation of fog would compute exactly how much attenuation occurs between the viewer and every object in the world and render the scene appropriately. However, implementations are free to approximate this ideal behavior, perhaps by computing the intersection of the viewing direction vector with any foggy regions and computing overall fogging parameters each time the scene is rendered.
Fog {
exposedField SFVec3f size 0 0 0
exposedField SFFloat maxVisibility 1
exposedField SFColor color 1 1 1
}
The PointLight node defines a point light source at a fixed 3D location. A point source illuminates equally in all directions; that is, it is omni-directional.
A PointLight illuminates everything within radius of its location. A PointLight's illumination falls off with distance as specified by three attenuation coefficients. The attenuation factor is 1/(attenuation[0] + attenuation[1]*r + attenuation[2]*r^2), where r is the distance of the light to the surface being illuminated. The default is no attenuation. Renderers that do not support a full attenuation model may approximate as necessary.
PointLight {
exposedField SFBool on TRUE
exposedField SFFloat intensity 1
exposedField SFFloat ambientIntensity 0
exposedField SFColor color 1 1 1
exposedField SFVec3f location 0 0 0
exposedField SFFloat radius 1
exposedField SFVec3f attenuation 1 0 0
}
The SpotLight node defines a light source that is placed at a fixed location in 3-space and illuminates in a cone along a particular direction.
The cone of light extends a maximum distance of radius from its location. The light's illumination falls off with distance as specified by three attenuation coefficients. The attenuation factor is 1/(attenuation[0] + attenuation[1]*r + attenuation[2]*r^2), where r is the distance of the light to the surface being illuminated. The default is no attenuation. Renderers that do not support a full attenuation model may approximate as necessary.
The intensity of the illumination may drop off as the ray of light diverges from the light's direction toward the edges of the cone. The angular distribution of light is controlled by the cutOffAngle, beyond which the illumination is zero, and the beamWidth, the angle at which the beam starts to fall off. Renderers that support a two cone model with linear fall off from full intensity at the inner cone to zero at the cutoff cone should use beamWidth for the inner cone angle. Renderers that attenuate using a cosine raised to a power, should use an exponent of exponent = 0.5*log(0.5)/log(cos(beamWidth)). When beamWidth >= PI/2 the illumination is uniform up to the cutoff angle, which is the default.
SpotLight {
exposedField SFBool on TRUE
exposedField SFFloat intensity 1
exposedField SFFloat ambientIntensity 0
exposedField SFColor color 1 1 1
exposedField SFVec3f location 0 0 0
exposedField SFVec3f direction 0 0 -1
exposedField SFFloat beamWidth 1.570796
exposedField SFFloat cutOffAngle 0.785398
exposedField SFFloat radius 1
exposedField SFVec3f attenuation 1 0 0
}
The Sound functional grouping includes the DirectedSound node.
ISSUE: What sound file formats should be required?
The DirectedSound node describes a sound which emits primarily in the direction defined by the direction vector. Where minRange and maxRange determine the extent of a PointSound, the extent of a DirectedSound is determined by four fields: minFront, minBack, maxFront, and maxBack.
Around the location of the emitter, minFront and minBack determine the extent of the ambient region in front of and behind the sound. If the location of the sound is taken as a focus of an ellipse, and the minBack and minFront values (in combination with the direction vector) as determining the two vertices, these three points describe an ellipse bounding the ambient region of the sound. Similarly, maxFront and maxBack determine the limits of audibility in front of and behind the sound; they describe a second, outer ellipse.
The inner ellipse is analogous to the sphere determined by the minRange field in the PointSound definition: within this ellipse, the sound is non-directional, with constant and maximal intensity. The outer ellipse is analogous to the sphere determined by the maxRange field in the PointSound definition and represents the limits of audibility of the sound. Between the two ellipses, the intensity drops off proportionally with distance and the sound is localized in space.
One advantage of this model is that a DirectedSound behaves as expected when approached from any angle; the intensity increases smoothly even if the emitter is approached from the back.
See the PointSound node for a description of all other fields.
DirectedSound {
field MFString name [ ]
field SFString description ""
exposedField SFFloat intensity 1
exposedField SFVec3f location 0 0 0
exposedField SFVec3f direction 0 0 1
exposedField SFFloat minFront 10
exposedField SFFloat maxFront 10
exposedField SFFloat minBack 10
exposedField SFFloat maxBack 10
exposedField SFBool loop FALSE
exposedField SFTime start 0
exposedField SFTime pause 0
}
This functional group includes only one node, the Shape node.
A Shape node has two fields: appearance and geometry. These fields, in turn, contain other nodes. The appearance field contains an Appearance node that has material, texture, and textureTransform fields (see the Appearance node). The geometry field contains a geometry node. See Subsidiary Nodes.
Shape {
field SFNode appearance NULL
field SFNode geometry NULL
}
The following groups of nodes are used only in fields within other nodes. They cannot stand alone in the scene graph.
A Shape node contains one geometry node in its geometry field. This node can be an IndexedFaceSet, IndexedLineSet, PointSet, or Text node. A geometry node can appear only in the geometry field of a Shape node. Geometry nodes usually contain Coordinate3, Normal, and TextureCoordinate2 nodes in specified SFNode fields. All geometry nodes are specified in a local coordinate system determined by the parent(s) nodes of the geometry.
The ccw field indicates whether the vertices are ordered in a counter-clockwise direction when the shape is viewed from the outside (TRUE). If the order is clockwise or unknown, this field value is FALSE. The solid field indicates whether the shape encloses a volume (TRUE). If nothing is known about the shape, this field value is FALSE. The convex field indicates whether all faces in the shape are convex (TRUE). If nothing is known about the faces, this field value is FALSE.
These hints allow VRML implementations to optimize certain rendering features. Optimizations that may be performed include enabling backface culling and disabling two-sided lighting. For example, if an object is solid and has ordered vertices, an implementation may turn on backface culling and turn off two-sided lighting. If the object is not solid but has ordered vertices, it may turn off backface culling and turn on two-sided lighting.
The IndexedFaceSet node represents a 3D shape formed by constructing faces (polygons) from vertices listed in the coord field. The coord field must contain a Coordinate3 node. IndexedFaceSet uses the indices in its coordIndex field to specify the polygonal faces. An index of -1 indicates that the current face has ended and the next one begins. The Coordinate3 node must contain at least as many vertex coordinates as the greatest index in the coordIndex field.
For descriptions of the coord, normal, and texCoord fields, see the Coordinate3, Normal, and TextureCoordinate2 nodes.
If the color field is not NULL then it must contain a Color node, whose colors are applied to the vertices or faces of the IndexedFaceSet as follows:
If the normal field is NULL, then the browser should automatically generate normals, using creaseAngle to determine if and how normals are smoothed across shared vertices.
If the normal field is not NULL, then it must contain a Normal node, whose normals are applied to the vertices or faces of the IndexedFaceSet in a manner exactly equivalent to that described above for applying colors to vertices/faces.
If the texCoord field is not NULL, then it must contain a TextureCoordinate2 node. The texture coordinates in that node are applied to the vertices of the IndexedFaceSet as follows:
If the texCoord field is NULL, a default texture coordinate mapping is calculated using the bounding box of the shape. The longest dimension of the bounding box defines the S coordinates, and the next longest defines the T coordinates. If two or all three dimensions of the bounding box are equal, then ties should be broken by choosing the X, Y, or Z dimension in that order of preference. The value of the S coordinate ranges from 0 to 1, from one end of the bounding box to the other. The T coordinate ranges between 0 and the ratio of the second greatest dimension of the bounding box to the greatest dimension.
See the introductory Geometry section for a description of the ccw, solid, convex, and creaseAngle fields.
IndexedFaceSet {
exposedField SFNode coord NULL
exposedField SFNode color NULL
exposedField SFNode normal NULL
exposedField SFNode texCoord NULL
field MFInt32 coordIndex [ ]
field MFInt32 colorIndex [ ]
field SFInt32 colorPerFace FALSE
field MFInt32 normalIndex [ ]
field SFInt32 normalPerFace FALSE
field MFInt32 textureCoordIndex [ ]
field SFBool ccw TRUE
field SFBool solid TRUE
field SFBool convex TRUE
field SFFloat creaseAngle 0
}
This node represents a 3D shape formed by constructing polylines from vertices listed in the coord field. IndexedLineSet uses the indices in its coordIndex field to specify the polylines. An index of -1 indicates that the current polyline has ended and the next one begins.
For descriptions of the coord field, see the Coordinate3 node.
Lines are not texture-mapped or affected by light sources.
If the color field is not NULL, it must contain a Color node, and the colors are applied to the line(s) as folows:
IndexedLineSet {
exposedField SFNode coord NULL
exposedField SFNode color NULL
field MFInt32 coordIndex 0
field MFInt32 colorIndex 0
field MFInt32 colorPerLine FALSE
}
The PointSet node represents a set of points listed in the coord field. PointSet uses the coordinates in order. The number of points in the set is specified by the numPoints field.
Points are not texture-mapped or affected by light sources.
If the color field is not NULL, it must contain a Color node that contains at least numPoints colors. Colors are always applied to each point in order.
PointSet {
exposedField SFNode coord NULL
field SFInt32 numPoints 0
field SFNode color NULL
}
The Text node represents one or more text strings specified using the UTF-8 encoding of the ISO10646 character set (UTF-8 encoding is described below). Note that ASCII is a subset of UTF-8, so all ASCII strings are also UTF-8.
The text strings are contained in the string field. The fontStyle field contains one FontStyle node that specifies the font size, font family and style, direction of the text strings, and any specific language rendering techniques that must be used for non-English text.
The justify field determines where the text is positioned in relation to the origin (0,0,0) of the object coordinate system. The values for the justify field are "BEGIN", "MIDDLE", and "END". For a left-to-right direction , "BEGIN" would specify left-justified text, "END" would specify right-justified text, and "MIDDLE" would specify centered text. See the FontStyle node for details of text placement.
The spacing field determines the spacing between multiple text strings. The size field of the FontStyle node specifies the height (in object space units) of glyphs rendered and determines the vertical spacing of adjacent lines of text. All subsequent strings advance in either X or Y by -(size * spacing). A value of 0 for spacing causes the string to be in the same position. A value of -1 causes subsequent strings to advance in the opposite direction.
The maxExtent field limits and scales the text string if the natural length of the string is longer than the maximum extent. If the text string is shorter than the maximum extent, it is not scaled. The maximum extent is measured horizontally for horizontal text (FontStyle node: horizontal=TRUE) and vertically for vertical text (FontStyle node: horizontal=FALSE).
The width field contains an MFFloat value that specifies the width of each text string. If the string is too short, it is stretched (either by scaling the text itself or by adding space between the characters). If the string is too long, it is compressed. If a width value is missing--for example, if there are four strings but only three width values--the missing values are considered to be 0.
For both the maxExtent and width fields, specifying a value of 0 indicates to allow the string to be any width.
Textures are applied to 3D text as follows. The texture origin is at the origin of the first string, as determined by the justification. The texture is scaled equally in both S and T dimensions, with the font height representing 1 unit. S increases to the right, T increases up.
UTF-8 Character Encodings
The 2 byte (UCS-2) encoding of ISO 10646 is identical to the Unicode standard.
In order to allow standard ASCII text editors to contiue to work with most VRML files, we have chosen to support the UTF-8 encoding of ISO 10646. This encoding allows ASCII text (0x0..0x7F) to appear without any changes and encodes all characters from 0x80.. 0x7FFFFFFF into a series of six or fewer bytes.
If the most significant bit of the first character is 0, then the remaining seven bits are interpreted as an ASCII character. Otherwise, the number of leading 1 bits will indicate the number of bytes following. There is always a 0 bit between the count bits and any data.
First byte could be one of the following. The X indicates bits available to encode the character.
0XXXXXXX only one byte 0..0x7F (ASCII) 110XXXXX two bytes Maximum character value is 0x7FF 1110XXXX three bytes Maximum character value is 0xFFFF 11110XXX four bytes Maximum character value is 0x1FFFFF 111110XX five bytes Maximum character value is 0x3FFFFFF 1111110X six bytes Maximum character value is 0x7FFFFFFF
All following bytes have this format: 10XXXXXX
A two byte example. The symbol for a registered trademark is "circled R registered sign" or 174 in both ISO/Latin-1 (8859/1) and ISO 10646. In hexadecimal, it is 0xAE. In HTML, it is ®. In UTF-8 it has the following two-byte encoding: 0xC2, 0xAE.
Text {
exposedField MFString string [ ]
field SFNode fontStyle NULL
field SFString justify "BEGIN" # "BEGIN","MIDDLE", "END"
field SFFloat spacing 1.0
exposedField SFFloat maxExtent 0.0
field MFFloat width [ ]
}
Geometric properties are always contained in the corresponding SFNode fields of geometry nodes such as the IndexedFaceSet, IndexedLineSet, and PointSet nodes.
This node defines a set of RGB colors to be used in the color fields of an IndexedFaceSet, IndexedLineSet, or PointSet node.
Color nodes are only used to specify multiple colors for a single piece of geometry, such as a different color for each face or vertex of an IndexedFaceSet. A Material node is used to specify the overall material parameters of a geometry. If both a Material and a Color node are specified for a geometry, the colors should ideally replace the diffuse component of the material.
Textures take precedence over colors; specifying both a Texture and a Color node for a geometry will result in the Color node being ignored.
Note that some browsers may not support this functionality, in which case an average color should be computed and used instead.
Color {
exposedField MFColor rgb []
}
This node defines a set of 3D coordinates to be used in the coord field of an IndexedFaceSet, IndexedLineSet, or PointSet node.
Coordinate3 {
exposedField MFVec3f point []
}
This node defines a set of 3D surface normal vectors to be used in the normal field of vertex-based shape nodes (IndexedFaceSet, IndexedLineSet, PointSet, ElevationGrid). This node contains one multiple-valued field that contains the normal vectors.
To save network bandwidth, it is expected that implementations will be able to automatically generate appropriate normals if none are given. However, the results will vary from implementation to implementation.
Normal {
exposedField MFVec3f vector []
}
This node defines a set of 2D coordinates to be used in the texCoord field to map textures to the vertices of PointSet, IndexedLineSet, IndexedFaceSet, and ElevationGrid objects.
Texture coordinates range from 0 to 1 across the texture. The horizontal coordinate, S, is specified first, followed by the vertical coordinate, T.
TextureCoordinate2 {
exposedField MFVec2f point []
}
The Appearance node occurs only within the appearance field of a Shape node. The value for any of the fields in this node can be NULL. However, if the field contains anything, it must contain one specific type of node. Specifically, the material field, if specified, must contain a Material node. The texture field, if specified, must contain a Texture2 node. The textureTransform field, if specified, must contain a Texture2Transform node.
Appearance {
exposedField SFNode material Material {}
exposedField SFNode texture NULL
exposedField SFNode textureTransform NULL
}
The Material, Texture2, and Texture2Transform appearance property nodes are always contained within fields of an Appearance node. The FontStyle node is always contained in the fontStyle field of a Text node.
The FontStyle node, which may only appear in the fontStyle field of a Text node, defines the size, font family, and style of the text font, as well as the direction of the text strings and any specific language rendering techniques that must be used for non-English text.
The size field specifies the height (in object space units) of glyphs rendered and determines the vertical spacing of adjacent lines of text. All subsequent strings advance in either X or Y by -(size*spacing). (See the Text node for a description of the spacing field.)
Font Family and Style: Font attributes are defined with the family and style fields. It is up to the browser to assign specific fonts to the various attribute combinations.
The family field contains an SFString value that can be "SERIF" (the default) for a serif font such as Times Roman; "SANS" for a sans-serif font such as Helvetica; or "TYPEWRITER" for a fixed-pitch font such as Courier.
The style field contains an SFString value that can be an empty string (the default); "BOLD" for boldface type; "ITALIC" for italic type; or "BOLD ITALIC" for bold and italic type.
Direction: The horizontal, leftToRight, and topToBottom fields indicate the direction of the text. The horizontal field indicates whether the text is horizontal (specified as TRUE, the default) or vertical (FALSE). The leftToRight field indicates whether the text progresses from left to right (specified as TRUE, the default) or from right to left (FALSE). The topToBottom field indicates whether the text progresses from top to bottom (specified as TRUE, the default), or from bottom to top (FALSE).
The justify field of the Text node determines where the text is positioned in relation to the origin (0,0,0) of the local coordinate system. The values for the justify field are "BEGIN", "MIDDLE", and "END". For a left-to-right direction (leftToRight = TRUE), "BEGIN" would specify left-justified text, "MIDDLE" would specify centered text, and "END" would specify right-justified text.
For horizontal text (horizontal = TRUE), the first line of text is positioned with its baseline (bottom of capital letters) at Y = 0. The text is positioned on the positive side of the X origin when leftToRight is TRUE and justify is "BEGIN"; the same positioning is used when leftToRight is FALSE and justify is "END". The text is on the negative side of the X origin when leftToRight is TRUE and justify is "END" (and when leftToRight is FALSE and justify is "BEGIN"). For justify = "MIDDLE" and horizontal = TRUE, each string will be centered at X = 0.
For vertical text (horizontal is FALSE), the first line of text is positioned with the left side of the glyphs along the Y axis. When topToBottom is TRUE and justify is "BEGIN" (or when topToBottom is FALSE and justify is "END"), the text is positioned with the top left corner at the origin. When topToBottom is TRUE and justify is "END" (or when topToBottom is FALSE and justify is "BEGIN"), the bottom left is at the origin. For justify = "MIDDLE" and horizontal = FALSE, the text is centered vertically at X = 0.
In the following tables, each small cross indicates where the X and Y axes should be in relation to the text.
horizontal = TRUE:
horizontal = FALSE:
Text Language: There are many languages in which the proper rendering of the text requires more than just a sequence of glyphs. The language field allows the author to specify which, if any, language specific rendering techniques to use. For simple languages, such as English, this field may be safely ignored.
The tag used to specify languages will follow RFC1766, "Tags for the Identification of Languages." This RFC specifies that a language tag may simply be a two-letter ISO 639 tag, for example "en" for English, "ja" for Japanese, or "sv" for Swedish. This may be optionally followed by a hyphen and a two-letter country code from ISO 3166. American English, for instance, could be specified as "en-US".
FontStyle {
field SFFloat size 1.0
field SFString family "SERIF" # "SERIF", "SANS", "TYPEWRITER"
field SFString style "" # "BOLD", "ITALIC", "BOLD ITALIC"
field SFBool horizontal TRUE
field SFBool leftToRight TRUE
field SFBool topToBottom TRUE
field SFString language ""
}
The Material node defines surface material properties for associated geometry nodes.
The fields in the Material node determine the way light reflects off an object to create color:
The lighting parameters defined by the Material node are the same parameters defined by the OpenGL lighting model. For a rigorous mathematical description of how these parameters should be used to determine how surfaces are lit, see the description of lighting operations in the OpenGL Specification. Also note that OpenGL specifies the specular exponent as a non-normalized 0-128 value, which is specified as a normalized 0-1 value in VRML (simply multiplying the VRML value by 128 to translate to the OpenGL parameter).
For rendering systems that do not support the full OpenGL lighting model, the following simpler lighting model is recommended:
A transparency value of 0 is completely opaque, a value of 1 is completely transparent. Browsers need not support partial transparency, but should support at least fully transparent and fully opaque surfaces, treating transparency values >= 0.5 as fully transparent.
Issues for Low-End Rendering Systems. Many low-end PC rendering systems are not able to support the full range of the VRML material specification. For example, many systems do not render individual red, green and blue reflected values as specified in the specularColor field. The following table describes which Material fields are typically supported in popular low-end systems and suggests actions for browser implementors to take when a field is not supported.
Field Supported? Suggested Action ambientIntensity No Ignore diffuseColor Yes Use specularColor No Ignore emissiveColor No Use in place of diffuseColor if != 0 0 0 shininess Yes Use transparency No Ignore
Rendering systems which do not support specular color may nevertheless support a specular intensity. This should be derived by taking the dot product of the specified RGB specular value with the vector [.32 .57 .11]. This adjusts the color value to compensate for the variable sensitivity of the eye to colors.
Likewise, if a system supports ambient intensity but not color, the same thing should be done with the ambient color values to generate the ambient intensity. If a rendering system does not support per-object ambient values, it should set the ambient value for the entire scene at the average ambient value of all objects.
It is also expected that simpler rendering systems may be unable to support both diffuse and emissive objects in the same world.
Material {
exposedField SFColor diffuseColor 0.8 0.8 0.8
exposedField SFFloat ambientIntensity 0.2
exposedField SFColor specularColor 0 0 0
exposedField SFColor emissiveColor 0 0 0
exposedField SFFloat shininess 0.2
exposedField SFFloat transparency 0
}
The Texture2 node defines a texture map and parameters for that map.
The texture can be read from the URL specified by the filename field. To turn off texturing, set the filename field to an empty string (""). Implementations should support the JPEG and PNG image file formats. Support for the GIF format and for MPEG is also recommended. If MPEG is supported, the fraction field specifies which frame of the sequence should be used as the texture. A fraction of 0 indicates that the first frame is displayed, and a fraction of 1 indicates that the last frame is displayed. Connecting this field to the fraction eventOut of a TimeSensor allows the texture to be animated by the MPEG movie.
If multiple URLs are presented, this expresses a descending order of preference. A browser may display a lower-preference URL while the higher-order file is not available. See the section on URLs and URNs.
Textures can also be specified inline by setting the image field to contain the texture data. Supplying both image and filename fields will result in undefined behavior.
Texture images may be one component (greyscale), two component (greyscale plus transparency), three component (full RGB color), or four-component (full RGB color plus transparency). An ideal VRML implementation will use the texture image to modify the diffuse color and transparency of an object's material (specified in a Material node), then perform any lighting calculations using the rest of the object's material properties with the modified diffuse color to produce the final image. The texture image modifies the diffuse color and transparency depending on how many components are in the image, as follows:
Browsers may approximate this ideal behavior to increase performance. One common optimization is to calculate lighting only at each vertex and combining the texture image with the color computed from lighting (performing the texturing after lighting). Another common optimization is to perform no lighting calculations at all when texturing is enabled, displaying only the colors of the texture image.
The repeatS and repeatT fields specify how the texture wraps in the S and T directions. If repeatS is TRUE (the default), the texture map is repeated outside the 0-to-1 texture coordinate range in the S direction so that it fills the shape. If repeatS is FALSE, the texture coordinates are clamped in the S direction to lie within the 0-to-1 range. The repeatT field is analogous to the repeatS field.
Texture2 {
exposedField MFString filename [ ]
exposedField SFImage image 0 0 0
exposedField SFFloat fraction 0
field SFBool repeatS TRUE
field SFBool repeatT TRUE
}
The Texture2Transform node defines a 2D transformation that is applied to texture coordinates. This node is used only in the textureTransform field of the Appearance node and affects the way textures are applied to the surfaces of the associated Geometry node. The transformation consists of (in order) a nonuniform scale about an arbitrary center point, a rotation about that same point, and a translation. This allows a user to change the size and position of the textures on shapes.
Texture2Transform {
field SFVec2f translation 0 0
field SFFloat rotation 0
field SFVec2f scaleFactor 1 1
field SFVec2f center 0 0
}
Geometric sensor nodes are children of a Transform node. They generate events with respect to the Transform's coordinate system and children.
Proximity sensors are nodes that generate events when the viewpoint enters, exits, and moves inside a space. A proximity sensor can be activated or deactivated by sending it an enabled event with a value of TRUE or FALSE.
A BoxProximitySensor generates isActive TRUE/FALSE events as the viewer enters/exits the region defined by its center and size fields. Ideally, implementations will interpolate viewpoint positions and timestamp the isActive events with the exact time the viewpoint first intersected the volume.
A BoxProximitySensor with a (0 0 0) size field (the default) will sense the region defined by the objects in its coordinate system. The axis-aligned bounding box of the Transform containing the BoxProximitySensor should be computed and used instead of the center and size fields in this case.
position and orientation events giving the position and orientation of the viewer in the BoxProximitySensor's coordinate system are generated when either the user or the coordinate system of the sensor moves and the viewer is inside the region being sensed.
Multiple BoxProximitySensors will generate events at the same time if the regions they are sensing overlap. Unlike ClickSensors, there is no notion of a BoxProximitySensor lower in the scene graph "grabbing" events.
A BoxProximitySensor that surrounds the entire world will have an enter time equal to the time that the world was entered and can be used to start up animations or behaviors as soon as a world is loaded.
BoxProximitySensor {
exposedField SFVec3f center 0 0 0
exposedField SFVec3f size 0 0 0
exposedField SFBool enabled TRUE
eventOut SFBool isActive
eventOut SFVec3f position
eventOut SFRotation orientation
}
A ClickSensor tracks the pointing device with respect to some geometry. This sensor can be activated or deactivated by sending it an enabled event with a value of TRUE or FALSE.
The ClickSensor generates events as the pointing device passes over some geometry. When the pointing device is over the geometry, this sensor will also generate button press and release events for the button associated with the pointing device. Typically, the pointing device is a mouse and the button is a mouse button.
isOver TRUE/FALSE events are generated as the pointing device moves over the ClickSensor's geometry. When the pointing device is unobstructed by any other surface and moves on top of the ClickSensor's geometry, an isOver TRUE event should be generated. When the pointing device moves and is no longer on top of the geometry, or some other geometry is obstructing the ClickSensor's geometry, an isOver FALSE event should be generated.
All of these events are generated only when the pointing device moves or the user clicks the button.
If the user presses the button associated with the pointing device while the cursor is located over its geometry, the ClickSensor will grab all further motion events from the pointing device until the button is released (other Click or Drag sensors will not generate events during this time). isActive TRUE/FALSE events are generated along with the press/release events. Motion of the pointing device while it has been grabbed by a ClickSensor is referred to as a "drag".
As the user drags the cursor over the ClickSensor's geometry, the point on that geometry which lies directly underneath the cursor is determined. When isOver and isActive are TRUE, hitPoint, hitNormal, and hitTexture events are generated whenever the pointing device moves. hitPoint events contain the 3D point on the surface of the underlying geometry, given in the ClickSensor's coordinate system. hitNormal events contain the surface normal at the hitPoint. hitTexture events contain the texture coordinates of that surface at the hitPoint, which can be used to support the 3D equivalent of an image map.
ClickSensor {
exposedField SFBool enabled TRUE
eventOut SFBool isOver
eventOut SFBool isActive
eventOut SFVec3f hitPoint
eventOut SFVec3f hitNormal
eventOut SFVec2f hitTexture
}
The CylinderSensor maps dragging motion into a rotation around the Y axis of its local space. The feel of the rotation is as if you were turning a rolling pin.
CylinderSensor {
exposedField SFFloat minAngle 0
exposedField SFVec2f maxAngle 0
exposedField SFBool enabled TRUE
eventOut SFVec3f trackPoint
eventOut SFRotation rotation
eventOut SFBool onCylinder
}
minAngle and maxAngle may be set to clamp rotation events to a range of values (measured in radians about the Y axis). If minAngle is greater than maxAngle, rotation events are not clamped.
Upon the initial click down on the CylinderSensor's geometry, the specific point clicked determines the radius of the cylinder used to map pointing device motion while dragging. trackPoint events always reflect the unclamped drag position on the surface of this cylinder, or in the plane perpendicular to the view vector if the cursor moves off this cylinder. An onCylinder TRUE event is generated at the initial click down; thereafter, onCylinder FALSE/TRUE events are generated if the pointing device is dragged off/on the cylinder.
The DiskSensor maps dragging motion into a rotation around the Z axis of its local space. The feel of the rotation is as if you were scratching on a record turntable.
DiskSensor {
exposedField SFFloat minAngle 0
exposedField SFVec2f maxAngle 0
exposedField SFBool enabled TRUE
eventOut SFVec3f trackPoint
eventOut SFRotation rotation
}
minAngle and maxAngle may be set to clamp rotation events to a range of values as measured in radians about the Z axis. If minAngle is greater than maxAngle, rotation events are not clamped. trackPoint events provide unclamped drag position in the XY plane.
The PlaneSensor maps dragging motion into a translation in two dimensions, in the XY plane of its local space.
PlaneSensor {
exposedField SFVec2f minPosition 0 0
exposedField SFVec2f maxPosition -1 -1
exposedField SFBool enabled TRUE
eventOut SFBool isOver
eventOut SFBool isActive
eventOut SFVec3f hitPoint
eventOut SFVec3f hitNormal
eventOut SFVec2f hitTexture
eventOut SFVec3f trackPoint
eventOut SFVec3f translation
}
minPosition and maxPosition may be set to clamp translation events to a range of values as measured from the origin of the XY plane. If the X or Y component of minPosition is greater than the corresponding component of maxPosition, translation events are not clamped in that dimension. If the X or Y component of minPosition is equal to the corresponding component of maxPosition, that component is constrained to the given value; this technique provides a way to implement a line sensor that maps dragging motion into a translation in one dimension. (There is no built-in line sensor node.)
trackPoint events provide unclamped drag position in in the XY plane.
The SphereSensor maps dragging motion into a free rotation about its center. The feel of the rotation is as if you were rolling a ball.
SphereSensor {
exposedField SFBool enabled TRUE
eventOut SFVec3f trackPoint
eventOut SFRotation rotation
eventOut SFBool onSphere
}
The free rotation of the SphereSensor is always unclamped.
Upon the initial click down on the SphereSensor's geometry, the point hit determines the radius of the sphere used to map pointing device motion while dragging. trackPoint events always reflect the unclamped drag position on the surface of this sphere, or in the plane perpendicular to the view vector if the cursor moves off of the sphere. An onSphere TRUE event is generated at the initial click down; thereafter, onSphere FALSE/TRUE events are generated if the pointing device is dragged off/on the sphere.
The Background, NavigationInfo, Script, TimeSensor, and WorldInfo nodes are not part of the world's transformational hierarchy.
The Background, NavigationInfo, and WorldInfo nodes are global nodes that affect everything in the scene. They can be used anywhere in the scene description and may appear in fields of a Script node. If more than one Background node appears in a file, the first Background node read is the one that is used; the same rule applies to the NavigationInfo and WorldInfo nodes.
The Background node is used to specify a color-ramp backdrop that simulates ground and sky planes, as well as an environment texture, or panorama, that is placed behind all geometry in the scene and in front of the backdrop.
The backdrop is conceptually a sphere with an infinite radius, painted with a smooth gradation of ground colors (starting with a circle straight downward and rising in concentric bands up to the horizon) and a separate gradation of sky colors (starting with a circle straight upward and falling in concentric bands down to the horizon). (It's acceptable to implement the backdrop as a cube painted in concentric square rings instead of as a sphere.) The groundRanges field is a list of floating point values that indicate the cutoff for each groundColor. Its implicit initial value is 0 radians (downward), and the final value given indicates the elevation angle of the horizon, where the ground color ramp and the sky color ramp meet. The skyRanges field implicitly starts at 0 radians (upward) and works its way down to pi radians. If groundColors is NULL, no ground colors are used.
The panorama is the image that is to be wrapped around the user, between the backdrop and the world's geometry. The panorama consists of a tall texture map consisting of six square submaps, each of which is mapped onto the faces of a cube surrounding the world. Ideally, the texture map should be a power of 2 pixels wide, and six times that many pixels high. The top square in the texture is mapped onto the "ceiling" of the world-cube; the next four are mapped onto the sides of the cube; and the final square is mapped onto the "floor" of the cube. Transparency values in the panorama image specify that the panorama is transparent in particular places, allowing the groundColors and skyColors to show through. (Often, the top and bottom texture squares will be entirely transparent, to allow sky and ground to show; the other four texture squares may depict mountains or other distant scenery. If the textures are run-length encoded, making entire squares transparent significantly reduces the texture file size.) By default, there is no panorama.
If multiple URLs are specified for the panorama field, they expresses a descending order of preference. A browser may display a URL for a lower-preference file while it is obtaining, or if it is unable to obtain, a higher-preference file. See also the section on URLs and URNs.
The first Background node found during reading of the world is used as the initial background. Subsequent Background nodes are ignored. The background may be changed by Script node API calls.
Ground colors, sky colors, and panoramic images do not translate with respect to the viewer, though they do rotate with respect to the viewer. That is, the viewer can never get any closer to the background, but can turn to examine all sides of the panorama cube, and can look up and down to see the concentric rings of ground and sky (if visible).
Background{
exposedfield MFColor groundColor [ 0.14 0.28 0.00, # light green
0.09 0.11 0.00 ]# to dark green
exposedField MFFloat groundRange [ .785 ] # horizon = 45 degrees
exposedField MFColor skyColor [ 0.02 0.00 0.26 # twilight blue
0.02 0.00 0.65 ]# to light blue
exposedField MFFloat skyRange [ .785 ] # horizon = 45 degrees
exposedField MFString panorama [ ]
}
The NavigationInfo node contains information for the viewer through several fields: type, speed, size, visibilityLimit, and headlight.
The type field specifies a navigation paradigm to use. The types that all VRML viewers should support are "WALK", "EXAMINE", "FLY", and "NONE". A walk viewer is used for exploring a virtual world. The viewer should (but is not required to) have some notion of gravity in this mode. A fly viewer is similar to walk except that no notion of gravity should be enforced. There should still be some notion of "up" however. An examine viewer is typically used to view individual objects and often includes (but does not require) the ability to spin the object and move it closer or further away. The "none" choice removes all viewer controls. The user navigate using only controls provided in the scene, such as guided tours. Also allowed are browser specific viewer types. These should include a suffix as described in the naming conventions section to prevent conflicts. The type field is multi-valued so that authors can specify fallbacks in case a browser does not understand a given type.
The speed is the rate at which the viewer travels through a scene in units per second. Since viewers may provide mechanisms to travel faster or slower, this should be the default or average speed of the viewer. In an examiner viewer, this only makes sense for panning and dollying--it should have no effect on the rotation speed.
The size field specifies parameters to be used in determining the camera dimensions for the purpose of collision detection and terrain following if the viewer type allows these. It is a multi-value field to allow several dimensions to be specified. The first value should be the allowable distance between the user's position and any collision geometry (as specified by Collision) before a collision is detected. The second should be the height above the terrain the camera should be maintained. The third should be the height of the tallest object over which the camera can "step". This allows staircases to be build with dimensions that can be ascended by all browsers. Additional values are browser dependent and all values may be ignored but if a browser interprets these values the first 3 should be interpreted as described above.
The visibilityLimit field sets the furthest distance the viewer is able to see. The browser may clip all objects beyond this limit, fade them into the background or ignore this field. A value of 0.0 (the default) indicates an infinite visibility limit.
The headlight field specifies whether a browser should turn a headlight on. A headlight is a directional light that always points in the direction the user is looking. Setting this field to TRUE allows the browser to provide a headlight, possibly with user interface controls to turn it on and off. Scenes that enlist precomputed lighting (e.g. radiosity solutions) can specify the headlight off here. The headlight should have intensity 1, color 1 1 1, and direction 0 0 -1.
The first NavigationInfo node found during reading of the world supplies the initial navigation parameters. Subsequent NavigationInfo nodes are ignored. The browser may be told to use a different NavigationInfo node using Script node API calls.
NavigationInfo {
exposedField MFString type "WALK"
exposedField SFFloat speed 1.0
exposedField MFFloat size 1.0
exposedField MFFloat visibilityLimit 0.0
exposedField SFBool headlight TRUE
}
Files that describe node behavior are referenced through a Script node. Each Script node has associated code in some programming language that is executed to carry out the Script node's function. That code will be referred to as "the script" in the rest of this description.
A Script node's scriptType field describes which scripting language is being used. The contents of the behavior field depends on which scripting language is being used. Typically the behavior field will contain URLs/URNs from which the script should be fetched.
Each scripting language supported by a browser defines bindings for the following functionality. See Appendices A and B for the standard Java and C language bindings.
The script is created, and any language-dependent or user-defined initialization is performed. The script should be able to receive and process events that are sent to it. Each event that can be received must be declared in the Script node using the same syntax as is used in a prototype definition:
eventIn type name
"eventIn" is a VRML keyword. The type can be any of the standard VRML field types, and name must be an identifier that is unique for this Script node.
The Script node should be able to generate events in response to the incoming events. Each event that can be generated must be declared in the Script node using the following syntax:
eventOut type name
If the Script node's mustEvaluate field is FALSE, the browser can delay sending input events to the script until its outputs are needed by the browser. If the mustEvaluate field is TRUE, the browser should send input events to the script as soon as possible, regardless of whether the outputs are needed. The mustEvaluate field should be set to TRUE only if the Script has effects that are not known to the browser (such as sending information across the network); otherwise, poor performance may result.
An example of a Script node is
Script {
behavior "http://foo.com/bar.class" ; MFSTRING
scriptType "javabc"
eventIn SFString name
eventIn SFBool selected
eventOut SFString lookto
field SFInt32 currentState 0
field SFBool mustEvaluate TRUE
}
The script should be able to read and write the fields of the corresponding Script node. The Script node is responsible for implementing the behavior of exposed fields; the browser will not automatically update the value of an exposed field and will not automatically generate an eventOut when an exposed field changes.
Once the script has access to some VRML node (via an SFNode or MFNode value either in one of the Script node's fields or passed in as an eventIn), the script should be able to read the contents of that node's exposed field. If the Script node's directOutputs field is TRUE, the script may also send events directly to any node to which it has access.
A script should also be able to communicate directly with the VRML browser to get and set global information such as navigation information, the current time, the current world URL, and so on.
It is expected that all other functionality (such as networking capabilities, multi-threading capabilities, and so on) will be provided by the scripting language.
Script {
field MFString behavior [ ]
field SFString scriptType ""
field SFBool mustEvaluate FALSE
field SFBool directOutputs FALSE
# And any number of:
eventIn eventTypeName eventName
field fieldTypeName fieldName initialValue
exposedField fieldTypeName fieldName initialValue
eventOut eventTypeName eventName
}
TimeSensors generate events as time passes. TimeSensors remain inactive until their startTime is reached. At the first simulation tick when "now" is greater than or equal to startTime, the TimeSensor will begin generating time and fraction events, which may be routed to other nodes to drive continuous animation or simulated behaviors.
The length of time a TimeSensor generates events is controlled using cycleInterval and cycleCount; a TimeSensor stops generating time events at time startTime+cycleInterval*cycleCount. The time events contain times relative to startTime, so they will start at zero and increase up to cycleInterval*cycleCount.
The forward and back fields control the mapping of time to fraction values. If forward is TRUE and back is FALSE (the default), fraction events will rise from 0.0 to 1.0 over each interval. If forward is FALSE and back is TRUE, the opposite will happen (fraction events will fall from 1.0 to 0.0 during each interval). If they are both TRUE, fraction events will alternate 0.0 to 1.0, 1.0 to 0.0, reversing direction on each interval. If they are both FALSE, then fraction and time events will be generated only once per cycle (and the fraction values generated will always be 0).
pauseTime may be set to interrupt the progress of a TimeSensor. If pauseTime is greater than startTime, time and fraction events will not be generated after the pause time. pauseTime is ignored if it is less than or equal to startTime.
A TimeSensor will generate an isActive TRUE event when it begins generating times, and will generate an isActive FALSE event when it stops generating times (either because pauseTime was reached or because time startTime+cycleInterval*cycleCount was reached).
If cycleCount is is less than or equal to 0, the TimeSensor will continue to tick continuously, as if the cycleCount is infinity. This use of the TimeSensor should be used with caution, since it incurs continuous overhead on the simulation.
Setting cycleCount to 1 and cycleInterval to 0 will result in a single event being generated at startTime; this can be used to build an alarm that goes off at some point in the future.
No guarantees are made with respect to how often a TimeSensor will generate time events, but TimeSensors are guaranteed to generate final fraction and time events at or after time (startTime+cycleInterval*cycleCount) if pauseTime is less than or equal to startTime.
TimeSensor {
exposedField SFTime startTime 0
exposedField SFTime pauseTime 0
exposedField SFTime cycleInterval 1
exposedField SFInt32 cycleCount 1
exposedField SFBool forward TRUE
exposedField SFBool back FALSE
eventOut SFBool isActive
eventOut SFTime time
eventOut SFFloat fraction
}
The WorldInfo node contains information about the world. The title of the world is stored in its own field, allowing browsers to display it--for instance, in their window border. Any other information about the world can be stored in the info field--for instance, the scene author, copyright information, and public domain information.
WorldInfo {
field SFString title ""
field MFString info [ ]
}
A Group node is a lightweight grouping node that can contain any number of children. It is equivalent to a Transform node, without the transformation fields.
PROTO Group [
field SFVec3f bboxCenter 0 0 0
field SFVec3f bboxSize 0 0 0
exposedField MFNode children [ ]
eventIn MFNode add_children
eventIn MFNode remove_children
] {
Transform {
bboxCenter IS bboxCenter
bboxSize IS bboxSize
children IS children
add_children IS add_children
remove_children IS remove_children
}
}
The LOD node is used to allow browsers to switch between various representations of objects automatically. The children of this node typically represent the same object or objects at varying levels of detail, from highest detail to lowest.
First the distance is calculated from the viewpoint, transformed into the local coordinate space of the LOD node (including any scaling transformations), to the center point of the LOD. If the distance is less than the first value in the range field, then the first level of the LOD is drawn. If between the first and second values in the range field, the second level is drawn, and so on.
If there are N values in the range field, the LOD should have N+1 nodes in its level field. Specifying too few levels will result in the last level being used repeatedly for the lowest levels of detail; if too many levels are specified, the extra children will be ignored. The exception to this rule is to leave the range field empty, which is a hint to the browser that it should choose a level automatically to maintain a constant display rate.
Each value in the range field should be greater than the previous value; otherwise results are undefined. Not specifying any values in the range field (the default) is a special case that indicates that the browser may decide which child to draw to optimize rendering performance.
Authors should set LOD ranges so that the transitions from one level of detail to the next are barely noticeable. Browsers may adjust which level of detail is displayed to maintain interactive frame rates, to display an already-fetched level of detail while a higher level of detail (contained in a WWWInline node) is fetched, or might disregard the author-specified ranges for any other implementation-dependent reason. Authors should not use LOD nodes to emulate simple behaviors, because the results will be undefined. For example, using an LOD node to make a door appear to open when the user approaches probably will not work in all browsers. Use a ProximitySensor instead.
For best results, specify ranges only where necessary, and nest LOD nodes with and without ranges. For example:
LOD {
range [100, 1000]
children [
LOD {
children [
Transform { ... detailed version... },
DEF LoRes Transform { ... less detailed version... }
]
},
USE LoRes,
Shape { } # Display nothing
]
}
In this example, the browser is free to choose either a detailed or a less-detailed version of the object when the viewer is closer than 100 meters. The browser should display the less-detailed version of the object if the viewer is between 100 and 1,000 meters and should display nothing at all if the viewer is farther than 1,000 meters. Browsers should try to honor the hints given by authors, and authors should try to give browsers as much freedom as they can to choose levels of detail based on performance.
PROTO LOD [
field MFFloat range [ ]
field SFVec3f center 0 0 0
exposedField MFNode levels [ ]
] {
DEF F Transform {
DEF PS BoxProximitySensor { center IS center }
}
DEF LODSCRIPT Script {
eventOut MFNode remove
eventOut MFNode add
eventOut SFVec3f maxRange
eventIn SFVec3f viewerPosition
field MFFloat range IS range
field MFNode levels IS levels
#
# Script must:
# -- set maxRange to maximum value in range[] field
# -- get viewerPosition, figure out which level should
# be seen, add/remove appropriate children
}
ROUTE F.position TO LODSCRIPT.viewerPosition
ROUTE LODSCRIPT.maxRange TO PS.size
ROUTE LODSCRIPT.remove TO F.removeChildren
ROUTE LODSCRIPT.add TO F.addChildren
}
The Switch grouping node traverses zero or one of its children (which are specified in the choices field).
The whichChild field specifies the index of the child to traverse, where the first child has index 0. If whichChild is less than zero or greater than the number of nodes in the choices field then nothing is chosen.
PROTO Switch [
exposedField SFInt32 whichChild -1
exposedField MFNode choices [ ]
] {
DEF F Transform {
}
DEF SWITCHSCRIPT Script {
eventOut MFNode remove
eventOut MFNode add
exposedField SFInt32 whichChild IS whichChild
exposedField MFNode children IS children
#
# Script must:
# -- keep whichChild up-to-date
# -- figure out which child should
# be seen when whichChild changes, add/remove
# appropriate children
}
ROUTE SWITCHSCRIPT.remove TO F.removeChildren
ROUTE SWITCHSCRIPT.add TO F.addChildren
}
The WWWAnchor grouping node causes some data to be fetched over the network when any of its children are chosen. If the data pointed to is a VRML world, then that world is loaded and displayed instead of the world of which the WWWAnchor is a part. If another data type is fetched, it is up to the browser to determine how to handle that data; typically, it will be passed to an appropriate, already-open (or newly spawned) general Web browser.
Exactly how a user "chooses" a child of the WWWAnchor is up to the VRML browser; typically, clicking on one of its children with the mouse will result in the new scene replacing the current scene. A WWWAnchor with an empty ("") name does nothing when its children are chosen.
The name is an arbitrary set of URLs. If multiple URLs are presented, this expresses a descending order of preference. A browser may display a lower-preference URL if the higher-order file is not available. See the section on URLs and URNs.
The description field in the WWWAnchor allows for a friendly prompt to be displayed as an alternative to the URL in the name field. Ideally, browsers will allow the user to choose the description, the URL, or both to be displayed for a candidate WWWAnchor.
A WWWAnchor may be used to take the viewer to a particular viewpoint in a virtual world by specifying a URL ending with "#viewpointName", where "viewpointName" is the name of a viewpoint defined in the world. For example:
WWWAnchor {
name "http://www.school.edu/vrml/someScene.wrl#OverView"
Cube { }
}
specifies an anchor that puts the viewer in the "someScene" world looking from the viewpoint named "OverView" when the Cube is chosen. If no world is specified, then the current scene is implied; for example:
WWWAnchor {
name "#Doorway"
children [ Sphere { } ]
}
will take the viewer to the viewpoint defined by the "Doorway" viewpoint in the current world when the sphere is chosen.
PROTO WWWAnchor [
field MFString name [ ]
field SFString description ""
exposedField MFNode children [ ]
] {
Group {
children [
DEF CS ClickSensor { },
Group { children IS children }
]
}
DEF ASCRIPT Script {
mustEvaluate TRUE
field MFString url IS name
eventIn SFBool loadWorld
#
# Script must load new world (using Script API) when
# ClickSensor is clicked
#
}
ROUTE CS.isActive TO ASCRIPT.loadWorld
}
The WWWInline node is a light-weight grouping node like Group that reads its children from anywhere in the World Wide Web. Exactly when its children are read is not defined; reading the children may be delayed until the WWWInline is actually displayed. A WWWInline with an empty name does nothing. The name is an arbitrary set of URLs.
A WWWInline's URLs must refer to a valid VRML file that contains a grouping or leaf node. Referring to non-VRML files or VRML files that do not contain a grouping or leaf node is undefined.
If multiple URLs are specified, then this expresses a descending order of preference. A browser may display a URL for a lower-preference file while it is obtaining, or if it is unable to obtain, the higher-preference file. See also the section on URLs and URNs.
If the WWWInline's bboxSize field specifies a non-empty bounding box (a bounding box is non-empty if at least one of its dimensions is greater than zero), then the WWWInline's object-space bounding box is specified by its bboxSize and bboxCenter fields. This allows an implementation to quickly determine whether or not the contents of the WWWInline might be visible. This is an optimization hint only; if the true bounding box of the contents of the WWWInline is different from the specified bounding box, results will be undefined.
PROTO WWWInline [
field MFString name [ ]
field SFVec3f bboxSize 0 0 0
field SFVec3f bboxCenter 0 0 0
] {
DEF G Group {
bboxSize IS bboxSize
bboxCenter IS bboxCenter
}
DEF ISCRIPT Script {
field MFString url IS name
eventOut MFNode children
#
# Script's initialization code should call browser's
# create node from URL function, then send resulting node out to
# children eventOut.
}
ROUTE ISCRIPT.children TO G.addChildren
}
The PointSound node defines a sound source located at a specific 3D location. The name field specifies a URL from which the sound is read. Implementations should support at least the ??? ??? sound file formats. Streaming sound files may be supported by browsers; otherwise, sounds should be loaded when the sound node is loaded. Browsers may limit the maximum number of sounds that can be played simultaneously.
If multiple URLs are specified, then this expresses a descending order of preference. A browser may use a URL for a lower-preference file while it is obtaining, or if it is unable to obtain, the higher-preference file. See also the section on URNs.
The description field is a textual description of the sound, which may be displayed in addition to or in place of playing the sound.
The intensity field adjusts the volume of each sound source; an intensity of 0 is silence, and an intensity of 1 is whatever intensity is contained in the sound file.
The sound source has a radius specified by the minRadius field. When the viewpoint is within this radius, the sound's intensity (volume) is constant, as indicated by the intensity field. Outside the minRadius, the intensity drops off to zero at a distance of maxRadius from the source location. If the two radii are equal, the drop-off is sharp and sudden. Otherwise, the drop-off should be proportional to the square of the distance of the viewpoint from the minRadius.
Browsers may also support spatial localizations of sound. However, within minRadius, localization should not occur, so intensity is constant in all channels. Between minRadius and maxRadius, the sound location should be the point on the minRadius sphere that is closest to the current viewpoint. This ensures a smooth change in location when the viewpoint leaves the minRadius sphere. Note also that an ambient sound can therefore be created by using a large minRadius value.
The loop field specifies whether or not the sound is constantly repeated. By default, the sound is played only once. If the loop field is FALSE, the sound has length "length," which is not specified in the VRML file but is implicit in the sound file pointed to by the URL in the name field. If the loop field is TRUE, the sound has an infinite length.
The start field specifies the time at which the sound should start playing. The pause field may be used to make a sound stop playing some time after it has started.
With the start time "start," pause time "pause," and current time "now," the rules are as follows:
if: now < start: OFF else if: now >+ start+length: OFF else if: (pause> start) AND (start <= now < pause) : ON else: ON
Whenever start, pause, or "now" changes, the above rules need to be applied to figure out if the sound is playing. If it is, then it should be playing the bit of sound at (now - start) or, if it is looping, fmod( now - start, realLength).
A sound's location in the scene graph determines its spatial location (the sound's location is transformed by the current transformation) and whether or not it can be heard. A sound can only be heard while it is part of the traversed scene; sound nodes underneath LOD nodes or Switch nodes will not be audible unless they are traversed. If it is later part of the traversal again, the sound picks up where it would have been had it been playing continuously.
PROTO PointSound [
field MFString name [ ]
field SFString description ""
exposedField SFFloat intensity 1
exposedField SFVec3f location 0 0 0
exposedField SFFloat minRange 10
exposedField SFFloat maxRange 10
exposedField SFBool loop FALSE
exposedField SFTime start 0
exposedField SFTime pause 0
] {
DirectedSound {
name IS name description IS description intensity IS intensity
location IS location loop IS loop start IS start pause IS pause
minFront IS minRange
minBack IS minRange
maxFront IS maxRange
maxBack IS maxRange
}
}
This node represents a simple cone whose central axis is aligned with the Y axis. By default, the cone is centered at (0,0,0) and has a size of -1 to +1 in all three directions. The cone has a radius of 1 at the bottom and a height of 2, with its apex at 1 and its bottom at -1.
The cone has two parts: the side and the bottom. Each part has an associated SFBool field that specifies whether it is visible (TRUE) or invisible (FALSE).
When a texture is applied to a cone, it is applied differently to the sides and bottom. On the sides, the texture wraps counterclockwise (from above) starting at the back of the cone. The texture has a vertical seam at the back, intersecting the YZ plane. For the bottom, a circle is cut out of the texture square and applied to the cone's base circle. The texture appears right side up when the top of the cone is rotated towards the -Z axis.
PROTO Cone [
field SFFloat bottomRadius 1
field SFFloat height 2
field SFBool side TRUE
field SFBool bottom TRUE
] {
... equivalent to an IndexedFaceSet plus generator script...
}
This node represents a cuboid aligned with the coordinate axes. By default, the cube is centered at (0,0,0) and measures 2 units in each dimension, from -1 to +1. A cube's width is its extent along its object-space X axis, its height is its extent along the object-space Y axis, and its depth is its extent along its object-space Z axis.
Textures are applied individually to each face of the cube; the entire texture goes on each face. On the front, back, right, and left sides of the cube, the texture is applied right side up. On the top, the texture appears right side up when the top of the cube is tilted toward the user. On the bottom, the texture appears right side up when the top of the cube is tilted towards the -Z axis.
PROTO Cube [
field SFFloat width 2
field SFFloat height 2
field SFFloat depth 2
] {
... equivalent to an IndexedFaceSet plus generator script...
}
This node represents a simple capped cylinder centered around the Y axis. By default, the cylinder is centered at (0,0,0) and has a default size of -1 to +1 in all three dimensions. You can use the radius and height fields to create a cylinder with a different size.
The cylinder has three parts: the side, the top (Y = +1) and the bottom (Y = -1). Each part has an associated SFBool field that indicates whether the part is visible (TRUE) or invisible (FALSE).
When a texture is applied to a cylinder, it is applied differently to the sides, top, and bottom. On the sides, the texture wraps counterclockwise (from above) starting at the back of the cylinder. The texture has a vertical seam at the back, intersecting the YZ plane. For the top and bottom, a circle is cut out of the texture square and applied to the top or bottom circle. The top texture appears right side up when the top of the cylinder is tilted toward the +Z axis, and the bottom texture appears right side up when the top of the cylinder is tilted toward the -Z axis.
PROTO Cylinder [
field SFFloat radius 1
field SFFloat height 2
field SFBool side TRUE
field SFBool top TRUE
field SFBool bottom TRUE
] {
... equivalent to an IndexedFaceSet plus generator script...
}
This node creates a rectangular grid of varying height, especially useful in modeling terrain. The model is primarily described by a scalar array of height values that specify the height of the surface above each point of the grid.
The verticesPerRow and verticesPerColumn fields indicate the number of grid points in the X and Z directions, respectively, defining a grid of (verticesPerRow-1) x (verticesPerColumn-1) rectangles. (Note that the number of columns of vertices is defined by verticesPerRow and the number of rows of vertices is defined by verticesPerColumn. Rows are numbered from 0 through verticesPerColumn-1; columns are numbered from 0 through verticesPerRow-1.)
The vertex locations for the rectangles are defined by the height field and the gridStep field:
Thus, the vertex corresponding to the ith row and jth column is placed at
( gridStep[0] * j, heights[ i*verticesPerRow + j ], gridStep[ 1 ] * i )
in object space, where
0 <= i < verticesPerColumn, and
0 <= j < verticesPerRow.
All points in a given row have the same Z value, with row 0 having the smallest Z value. All points in a given column have the same X value, with column 0 having the smallest X value.
The default texture coordinates range from [0,0] at the first vertex to [1,1] at the far side of the diagonal. The S texture coordinate will be aligned with X, and the T texture coordinate with Z.
The colorPerQuad field determines whether colors (if specified in the color field) should be applied to each vertex or each quadrilateral of the ElevationGrid. If colorPerQuad is TRUE and the color field is not NULL, then the color field must contain a Color node containing at least (verticesPerColumn-1)*(verticesPerRow-1) colors. If colorPerQuad is FALSE and the color field is not NULL, then the color field must contain a Color node containing at least verticesPerColumn*verticesPerRow colors.
See the introductory Geometry section for a description of the ccw, solid, and creaseAngle fields.
By default, the rectangles are defined with a counterclockwise ordering, so the Y component of the normal is positive. Setting the ccw field to FALSE reverses the normal direction. Backface culling is enabled when the ccw field and the solid field are both TRUE (the default).
PROTO ElevationGrid [
field SFInt32 verticesPerColumn 0
field SFInt32 verticesPerRow 0
field SFVec2f gridStep [ 1 1 ]
field MFFloat height [ ]
exposedField SFNode color NULL
exposedField SFNode normal NULL
exposedField SFNode texCoord NULL
field SFInt32 colorPerQuad FALSE
field SFInt32 normalPerQuad FALSE
field SFBool ccw TRUE
field SFBool solid TRUE
field SFFloat creaseAngle 0
] {
... equivalent to an IndexedFaceSet plus generator script...
}
The GeneralCylinder node is used to parametrically describe numerous families of shapes: extrusions (along an axis or an arbitrary path), surfaces of revolution, and bend/twist/taper objects.
A GeneralCylinder is defined by a 2D crossSection piecewise linear curve (described as a series of connected vertices), a 3D spine piecewise linear curve (also described as a series of connected vertices), a list of floating-point width parameters, and a list of floating-point twist parameters (in radians). Shapes are constructed as follows: The cross-section curve, which starts as a curve in the XZ plane, is scaled about the origin by the first width parameter, twisted counter-clockwise about the origin by the first twist parameter, and translated by the vector given as the first vertex of the spine curve. It is then extruded through space along the first segment of the spine curve. Next, it is scaled and twisted by the second width and twist parameters and extruded by the second segment of the spine, and so on.
A transformed cross section is found for each joint (that is, at each vertex of the spine curve, where segments of the generalized cylinder connect), and the joints and segments are connected to form the surface. No check is made for self-penetration. Each transformed cross section is determined as follows:
For all points other than the first or last: The tangent for spine[i] is found by normalizing the vector defined by (spine[i+1] - spine[i-1]).
If the spine curve is closed: The first and last points need to have the same tangent. This tangent is found as above, but using the points spine[0] for spine[i], spine[1] for spine[i+1] and spine[n-2] for spine[i-1], where spine[n-2] is the next to last point on the curve. The last point in the curve, spine[n-1], is the same as the first, spine[0].
If the spine curve is not closed: The tangent used for the first point is just the direction from spine[0] to spine[1], and the tangent used for the last is the direction from spine[n-2] to spine[n-1].
In the simple case where the spine curve is flat in the XY plane, these rotations are all just rotations about the Z axis. In the more general case where the spine curve is any 3D curve, you need to find the destinations for all 3 of the local X, Y, and Z axes so you can completely specify the rotation. The Z axis is found by taking the cross product of
(spine[i-1] - spine[i]) and (spine[i+1] - spine[i]).
If the three points are collinear then this value is zero, so take the value from the previous point. Once you have the Z axis (from the cross product) and the Y axis (from the approximate tangent), calculate the X axis as the cross product of the Y and Z axes.
5. Finally, the cross section is translated to the location of the spine point.
Surfaces of revolution: If the cross section is an approximation of a circle and the spine is straight, then the GeneralCylinder is equivalent to a surface of revolution, where the width parameters define the width of the cross section along the spine.
Cookie-cutter extrusions: If both the width and spine are straight, then the cross section acts like a cookie cutter, with the thickness of the cookie equal to the length of the spine.
Bend/twist/taper objects: These shapes are the result of using all fields. The spine curve bends the extruded shape defined by the cross section, the twist parameters twist it around the spine, and the width parameters taper it (by scaling about the spine).
GeneralCylinder has three parts: the sides, the beginCap (the surface at the initial end of the spine) and the endCap (the surface at the final end of the spine). Each part has an associated SFBool field that indicates whether the part exists (TRUE) or doesn't exist (FALSE).
When the beginCap or endCap fields are specified as TRUE, planar cap surfaces will be generated regardless of whether the crossSection is a closed curve. (If crossSection isn't a closed curve, the caps are generated as if it were -- equivalent to adding a final point to crossSection that's equal to the initial point. Note that an open surface can still have a cap, resulting (for a simple case) in a shape something like a soda can sliced in half vertically.) These surfaces are generated even if spine is also a closed curve. If a field value is FALSE, the corresponding cap is not generated.
GeneralCylinder automatically generates its own normals. Orientation of the normals is determined by the vertex ordering of the triangles generated by GeneralCylinder. The vertex ordering is in turn determined by the crossSection curve. If the crossSection is drawn counterclockwise, then the polygons will have counterclockwise ordering when viewed from the 'outside' of the shape (and vice versa for clockwise ordered crossSection curves).
Texture coordinates are automatically generated by general cylinders. Textures are mapped like the label on a soup can: the coordinates range in the U direction from 0 to 1 along the crossSection curve (with 0 corresponding to the first point in crossSection and 1 to the last) and in the V direction from 0 to 1 along the spine curve (again with 0 corresponding to the first listed spine point and 1 to the last). When crossSection is closed, the texture has a seam that follows the line traced by the crossSection's start/end point as it travels along the spine. If the endCap and/or beginCap exist, the crossSection curve is cut out of the texture square and applied to the endCap and/or beginCap planar surfaces. The beginCap and endCap textures' U and V directions correspond to the X and Z directions in which the crossSection coordinates are defined.
See the introductory Geometry section for a description of the ccw, solid, convex, and creaseAngle fields.
PROTO GeneralCylinder [
field MFVec3f spine [ 0 0 0, 0 1 0 ]
field MFVec2f crossSection [ 1 1, -1 1, -1 -1, 1 -1 ]
field MFFloat width [ 1, 1 ]
field MFFloat twist [ 0, 0 ]
field SFBool sides TRUE
field SFBool beginCap TRUE
field SFBool endCap TRUE
field SFBool ccw TRUE
field SFBool solid TRUE
field SFBool convex TRUE
field SFFloat creaseAngle 0
] {
... equivalent to an IndexedFaceSet plus generator script...
}
The Sphere node represents a sphere. By default, the sphere is centered at the origin and has a radius of 1.
Spheres generate their own normals. When a texture is applied to a sphere, the texture covers the entire surface, wrapping counterclockwise from the back of the sphere. The texture has a seam at the back on the YZ plane.
PROTO Sphere [
field SFFloat radius 1
] {
... equivalent to an IndexedFaceSet plus generator script...
}
Interpolators are nodes that are useful for doing keyframed animation. Given a sufficiently powerful scripting language, all of these interpolators could be implemented using Script nodes (browsers might choose to implement these as pre-defined prototypes of appropriately defined Script nodes). We believe that keyframed animation will be common enough to justify the inclusion of these classes as built-in types.
Interpolator node names are defined based on the concept of what is to be interpolated: an index, orientation, coordinates, position, color, normals, etc. The fields for each interpolator provide the details on what the interpolators are affecting.
This node interpolates among a set of MFColor values, to produce MFColor outValue events. The number of colors in the values field must be an integer multiple of the number of keyframe times in the keys field; that integer multiple defines how many colors will be contained in the outValue events. For example, if 7 keyframe times and 21 colors are given, each keyframe consists of 3 colors; the first keyframe will be colors 0,1,2, the second colors 3,4,5, etc. The color values are linearly interpolated in each coordinate.
The description of MF values in and out belongs in the general interpolator section above, or maybe we should split up the interpolators into single-valued and multi-valued sections.
PROTO ColorInterpolator [
exposedField MFFloat keys []
exposedField MFColor values []
eventIn SFFloat set_fraction
eventOut MFColor outValue
] {
Script {
exposedField MFFloat keys IS keys
exposedField MFColor values IS values
eventIn SFFloat set_fraction IS set_fraction
eventOut MFColor outValue IS outValue
#
# Does the math to map input fraction into values based on keys...
}
}
This node linearly interpolates among a set of MFVec3f values. This would be appropriate for interpolating vertex positions for a geometric morph.
The number of coordinates in the values field must be an integer multiple of the number of keyframe times in the keys field; that integer multiple defines how many coordinates will be contained in the outValue events.
PROTO Coordinate3Interpolator [
exposedField MFFloat keys []
exposedField MFVec3f values []
eventIn SFFloat set_fraction
eventOut MFVec3f outValue
] {
Script {
exposedField MFFloat keys IS keys
exposedField MFVec3f values IS values
eventIn SFFloat set_fraction IS set_fraction
eventOut MFVec3f outValue IS outValue
#
# Does the math to map input fraction into values based on keys...
}
}
This node interpolates among a set of multi-valued Vec3f values, suitable for transforming normal vectors. All output vectors will have been normalized by the interpolator.
The number of normals in the values field must be an integer multiple of the number of keyframe times in the keys field; that integer multiple defines how many normals will be contained in the outValue events.
PROTO NormalInterpolator [
exposedField MFFloat keys []
exposedField MFVec3f values []
eventIn SFFloat set_fraction
eventOut MFVec3f outValue
] {
Script {
exposedField MFFloat keys IS keys
exposedField MFVec3f values IS values
eventIn SFFloat set_fraction IS set_fraction
eventOut MFVec3f outValue IS outValue
#
# Does the math to map input fraction into values based on keys...
}
}
This node interpolates among a set of SFRotation values. The rotations are absolute in object space and are, therefore, not cumulative. The values field must contain exactly as many rotations as there are keyframe times in the keys field, or an error will be generated and results will be undefined.
PROTO OrientationInterpolator [
exposedField MFFloat keys []
exposedField MFRotation values []
eventIn SFFloat set_fraction
eventOut SFRotation outValue
] {
Script {
exposedField MFFloat keys IS keys
exposedField MFRotation values IS values
eventIn SFFloat set_fraction IS set_fraction
eventOut SFRotation outValue IS outValue
#
# Does the math to map input fraction into values based on keys...
}
}
This node linearly interpolates among a set of SFVec3f values. This would be appropriate for interpolating a translation.
PROTO PositionInterpolator [
exposedField MFFloat keys []
exposedField MFVec3f values []
eventIn SFFloat set_fraction
eventOut SFVec3f outValue
] {
Script {
exposedField MFFloat keys IS keys
exposedField MFVec3f values IS values
eventIn SFFloat set_fraction IS set_fraction
eventOut SFVec3f outValue IS outValue
#
# Does the math to map input fraction into values based on keys...
}
}
This node linearly interpolates among a set of SFFloat values. This interpolator is appropriate for any parameter defined using a single floating point value, e.g., width, radius, intensity, etc. The values field must contain exactly as many numbers as there are keyframe times in the keys field, or an error will be generated and results will be undefined.
PROTO ScalarInterpolator [
exposedField MFFloat keys []
exposedField MFFloat values []
eventIn SFFloat set_fraction
eventOut SFFloat outValue
] {
Script {
exposedField MFFloat keys IS keys
exposedField MFFloat values IS values
eventIn SFFloat set_fraction IS set_fraction
eventOut SFFloat outValue IS outValue
#
# Does the math to map input fraction into values based on keys...
}
}