AdvancedAppearance
The AdvancedAppearance node enables you to use advanced texturing techniques such as multiple texturing.
Node description
EXTERNPROTO AdvancedAppearance [ exposedField SFNode material NULL exposedField MFNode textures [] exposedField MFString mappingTypes [] exposedField MFFloat weights [] # [0, inf) exposedField SFFloat materialBlending 0 # [0, 1] exposedField MFNode textureTransforms [] exposedField MFString backgroundFactor [] exposedField MFString foregroundFactor [] ] [ "urn:inet:parallelgraphics.com:cortona:AdvancedAppearance" "http://www.cortona3d.com/source/extensions.wrl#AdvancedAppearance" ]
material The material field, if specified, contains a Material node. |
textures The textures field specifies a set of 2D textures for multi-texturing. The texture field, if specified, contains one of the various types of texture nodes (ImageTexture, MovieTexture, or PixelTexture). If the texture node is NULL or the texture field is unspecified, the object that references this Appearance is not textured. |
mappingTypes The mappingTypes field defines a texture map type. The possible types are: "SIMPLE" - ordinary mapping that all VRML browsers support, "ENVIRONMENT" - this simulates the reflecting surfaces. When there are several textures with the "SIMPLE" map type, it is possible to define individual mapping for each texture by using several sets of texture indexes in the texCoordIndex field of the geometry node. The texCoordIndex field may contain N * L indexes, where N is the number of textures with the "SIMPLE" map type, L - the number of indexes in the coordIndex field. |
weights The weights field specifies a set of weights that are required to mix different textures. In Cortona 4.0 this field is ignored and the backgroundFactor and foregroundFactor fields are used for mixing textures. |
materialBlending The materialBlending field specifies how to combine textures and materials on associated geometry. The value of materialBlending ranges from 0 to 1. If you don't specify any textures (the textures field is empty) or material (material is NULL), no combination happens. The weights required for mixing can be computed as: if(textures.count == 0) Wmaterial = 1; // a material is used else if(material == NULL) Wmaterial = 0; // textures are used else // textures and material are combined Wmaterial = materialBlending. |
textureTransforms The textureTransforms field specifies a set of 2D transformations that are applied to different textures that are specified in the textures field. The field, if specified, contains a list of TextureTransform nodes. Descriptions of the TextureTransform node are provided in the VRML97 specification (see 6.49, TextureTransform). |
BackgroundFactor, foreGroundFactor The backgroundFactor and foreGroundFactor fields specify the sets of factors required to mix textures. |
Multi-texturing is implemented by the multi-pass rendering. On each pass the successive texture from the textures node is mixed with the color resulting from the previous pass according to the following formula:
C_{MT}(i) = C_{B} * F_{B}(i) + C_{F} * F_{F}(i), where C_{MT}(i) - the color resulting from the given pass, i - the texture number in the textures node (the pass number), C_{B} - the pixel color resulting from the previous pass (C_{MT}(i - 1)), or back color (the frame-buffer contents before rendering) for the first pass, C_{F} - the pixel color of the texture with the number i, F_{B}(i) - the factor defined in the backgroundFactor field, F_{F}(i) - the factor defined in the foregroundFactor field.
All colors are considered to have four components (RGBA). If there is no alpha channel (for example, the texture or back color has no alpha), the alpha value is considered to be 1 (entirely nontransparent color) i.e. the alpha channel takes part in all calculations equally with the other color components. The backgroundFactor and foreGroundFactor fields can take on the following values:
Value | Factor |
DEFAULT | default |
ZERO | 0 |
ONE | 1 |
FORE_COLOR | C_{F} |
INV_FORE_COLOR | 1 - C_{F} |
FORE_ALPHA | A_{F} |
INV_FORE_ALPHA | 1 - A_{F} |
BACK_COLOR | C_{B} |
INV_BACK_COLOR | 1 - C_{B} |
BACK_ALPHA | A_{B} |
INV_BACK_ALPHA | 1 - A_{B} |
A_{F} - the alpha value resulting from the given pass,
A_{B} - the alpha value resulting from the previous pass or from the back color. (If there is no alpha channel A_{B} = 1).
Only GeForce adapters support the last two values. So for the rest display adapters the "BACK_ALPHA" value is equivalent to "ONE", and "INV_BACK_ALPHA" is equivalent to "ZERO".
If the values in the backgroundFactor and foreGroundFactor fields are not defined or set to "DEFAULT", they are determined by default according to the texture type (see the table below). The value of C_{F} also depends on the texture type. If the material is defined (lighting on), the intensity textures are modulating by the diffuse color of the material. If all textures have alpha channels, the material transparency is ignored i.e. it is considered to be 0, and alpha from the textures is used. But if there is at least one texture without alpha the material transparency modulates the alpha channel of all textures.
Texture type | backgroundFactor by default |
foregroundFactor by default |
C_{F} lighting on |
C_{F} lighting off |
Intensity | "ZERO" | "ONE" | D_{M} * C_{T} | C_{T} |
Intensity + Alpha | "INV_FORE_ALPHA" | "FORE_ALPHA" | D_{M} * C_{T} | C_{T} |
RGB | "ZERO" | "ONE" | C_{T} | C_{T} |
RGB + Alpha | "INV_FORE_ALPHA" | "FORE_ALPHA" | C_{T} | C_{T} |
C_{T} - is the color of the texture (all components are equal for intensity textures)
D_{M} - is the diffuse color of the material (the Material.diffuseColor field).
For compatibility with the standard specification, the following is implemented: if all textures have alpha channels, the material transparency is ignored i.e. it is considered to be 0, and the alpha from the textures is used. But if there is at least one texture without alpha the material transparency modulates the alpha channel of all textures. The AF value is calculated according to the formula:
A_{F} = A_{T} * (1 - T_{M}), where A_{T} - the alpha value of the texture (for 1- and 3-component textures A_{T} = 1) T_{M} - the Material.transparency field value (or 0 if all textures have the alpha channel)
The color obtained after multi-texturing C_{MT} is processed in the following way:
Lighting off The resulting color is calculated by the formula: C = B_{M} * E_{M} + (1 - B_{M}) * C_{MT}, where C - is the resulting color of the pixel, B_{M} - is the coefficient of the material blending (the materialBlending field), E_{M} - is the emissive color of the material (the Material.emissiveColor field). |
Lighting on The resulting color of the pixel is calculated by the standard formula of the VRML lighting model where a diffuse factor (O_{Drgb}) is set to the following color: O_{Drgb} = B_{M} * D_{M} + (1 - B_{M}) * C_{MT} The resulting color C is combined with the color resulting from the previous pass (which is equal to C_{MT}) and with the transparency of Material (the Material.transparency field) according to the following formula: (1 - T_{M}) * C + T_{M} * C_{MT} |
BumpMap
The BumpMap node specifies bump-effect (illusion of bumps, or variations in surface depth on an otherwise flat surface) for a 3D object.
EXTERNPROTO BumpMap [ exposedField SFNode texture exposedField SFVec3f direction 0 0 -1 # (-inf,inf) ] [ "urn:inet:parallelgraphics.com:cortona:BumpMap" "http://www.cortona3d.com/source/extensions.wrl#BumpMap" ]
Fields and events
texture Contains a texture bump map which can be given by the ImageTexture, PixelTexture, MovieTexture, CubeEnvironment, or MipMap nodes. |
direction Specifies the direction of a light source (analogous of the DirectionalLight node). |
Each pixel of a resultant bump texture has grey color: red, green and blue components of its color are equal. The value of these components is calculated as follows:
- the direction vector is transformed to the global coordinates;
- the obtained vector is scalarly multiplied by the color of the corresponding pixel of the texture bump map, specified in the texture field.
If the BumpMap node is used as a value of the textures field of the AdvancedAppearance node, other fields of this node have the following default values:
backgroundFactor = FORE_COLOR
foregroundFactor = ZERO
or:
backgroundFactor = ZERO
foregroundFactor = BACK_COLOR
Important: This node is supported by GeForce and latest ATI Radeon video cards when the DirectX Renderer (Concorde DX7) is chosen, or at computers with the Pentium IV processor when the R98 Renderer (software renderer) is selected.
CompositeTexture
The CompositeTexture3D and CompositeTexture2D nodes allow for adding composite textures to the 3D scene. You must have DirectX 9.0c installed and activated DirectX renderer with Auto or Concorde DX9 option in Cortona3D Viewer.
CompositeTexture3D
EXTERNPROTO CompositeTexture3D [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField MFNode children NULL exposedField SFInt32 pixelWidth -1 exposedField SFInt32 pixelHeight -1 exposedField SFBool repeatS TRUE exposedField SFBool repeatT TRUE exposedField SFNode background NULL exposedField SFNode fog NULL exposedField SFNode navigationInfo NULL exposedField SFNode viewpoint NULL ] [ "urn:inet:parallelgraphics.com:cortona:CompositeTexture3D" "http://www.cortona3d.com/source/extensions.wrl#CompositeTexture3D" ]
The CompositeTexture3D node represents a texture mapped onto a 3D object that is composed of a 3D scene.
User interaction and the standard user navigation on the textured scene are disabled.
The children field is the list of 3D children nodes that define the 3D scene that forms the texture map.
The addChildren eventIn specifies a list of nodes that shall be added to the children field.
The removeChildren eventIn specifies a list of nodes that shall be removed from the children field.
The pixelWidth and pixelHeight fields specify the ideal size in pixels of this map. The default values result in an undefined size being used. This is a hint for the content creator to define the quality of the texture mapping.
The background field specifies the Background of the current texture. It may only contain Background node.
The fog field specifies the Fog node.
The navigationInfo field specifies the NavigationInfo node.
The viewpoint field specifies the Viewpoint node.
The repeatS and repeatT fields specify how the texture wraps in the S and T directions.
CompositeTexture2D
EXTERNPROTO CompositeTexture2D [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField MFNode children NULL exposedField SFInt32 pixelWidth -1 exposedField SFInt32 pixelWidth -1 exposedField SFBool repeatS TRUE exposedField SFBool repeatT TRUE exposedField SFNode background NULL exposedField SFNode viewport NULL ] [ "urn:inet:parallelgraphics.com:cortona:CompositeTexture2D" "http://www.cortona3d.com/source/extensions.wrl#CompositeTexture2D" ]
The CompositeTexture2D node represents a texture that is composed of a 2D scene, which may be mapped onto another object.
The children field contains a list of 2D children nodes that define the 2D scene that is to form the texture map.
The addChildren eventIn specifies a list of nodes that shall be added to the children field.
The removeChildren eventIn specifies a list of nodes that shall be removed from the children field.
TThe pixelWidth and pixelHeight fields specify the ideal size in pixels of this map. The default values result in an undefined size being used. This is a hint for the content creator to define the quality of the texture mapping.
The semantics of the background and viewport fields are identical to the semantics of the Layer2D fields of the same name.
The repeatS and repeatT fields specify how the texture wraps in the S and T directions.
CortonaExtrusion
CortonaExtrusion is an extension of the standard Extrusion node. It allows for preventing the twist of extrusion models that have complicated spines. CortonaExtrusion has preventTwist field, which value determines how the Z-axis of the SCP is computed.
If preventTwist is FALSE, then CortonaExtrusion is identical to the standard Extrusion. The orientation of each cross-section is calculated from the local curvature of the spine. In some cases this algorithm can cause undesirable twists and distortions of the surface.
The Z-axis for points other than the first or last is determined as follows:
z = (spine[i+1] - spine[i]) * (spine[i-1] - spine[i])
If preventTwist is TRUE, then the orientation of each cross-section (except the first one) is approximately parallel to the orientation of the previous cross-section. This algorithm can help avoid undesirable twists and distortions.
The Z-axis for points other than the first or last is determined as follows:
z = x[i-1] * y[i]
EXTERNPROTO CortonaExtrusion [ eventIn MFVec2f set_crossSection eventIn MFRotation set_orientation eventIn MFVec2f set_scale eventIn MFVec3f set_spine field SFBool preventTwist FALSE field SFBool beginCap TRUE field SFBool ccw TRUE field SFBool convex TRUE field SFFloat creaseAngle 0 field MFVec2f crossSection [1 1 1 -1 -1 -1 -1 1 1 1] field SFBool endCap TRUE field MFRotation orientation [0 0 1 0] field MFVec2f scale [1 1] field SFBool solid TRUE field MFVec3f spine [0 0 0 0 1 0] ] [ "urn:inet:parallelgraphics.com:cortona:CortonaExtrusion" "http://www.cortona3d.com/source/extensions.wrl#CortonaExtrusion" ]
CubeEnvironment
The CubeEnvironment node specifies an environment cube texture map shape for simulating reflections on 3D objects in the scene.
EXTERNPROTO CubeEnvironment [ exposedField SFNode backTexture exposedField SFNode bottomTexture exposedField SFNode frontTexture exposedField SFNode leftTexture exposedField SFNode rightTexture exposedField SFNode topTexture ] [ "urn:inet:parallelgraphics.com:cortona:CubeEnvironment" "http://www.cortona3d.com/source/extensions.wrl#CubeEnvironment" ]
Fields and events
backTexture Specifies the back texture in the cube map shape. |
bottomTexture Specifies the bottom texture in the cube map shape. |
frontTexture Specifies the front texture in the cube map shape. |
leftTexture Specifies the left texture in the cube map shape. |
rightTexture Specifies the right texture in the cube map shape. |
topTexture Specifies the top texture in the cube map shape. |
Following nodes can be used as values of the above fields: ImageTexture, PixelTexture, MovieTexture, BumpMap, and MipMap. It is not possible to use the BumpMap or MipMap nodes as values of the fields if the CubeEnvironment node is in its turn specified in one of these two nodes.
Important: This node is supported by most video cards when the DirectX Renderer (Concorde DX7) or OpenGL Renderer is selected. It is strongly recommended to install the latest version of DirectX and update the video card driver (from its manufacturer's Web site) before viewing VRML scenes containing this node.
DropSensor
The DropSensor node generates events based on input from a pointing device. Retrieves an object's uniform resource locator (URL) of an object (resource) dragged to the 3D window.
To texture an object, drag and drop the texture or links (in Netscape Navigator) onto the box in the 3D window. You can also drag a link to any of image file from your local drive or Internet.
Node description
EXTERNPROTO DropSensor [ exposedField SFBool enabled TRUE eventOut SFVec3f hitPoint eventOut SFVec3f hitNormal eventOut SFVec2f hitTexCoord eventOut SFTime dropTime eventOut MFNode nodeChain eventOut MFString url ] [ "urn:inet:parallelgraphics.com:cortona:DropSensor" "http://www.cortona3d.com/source/extensions.wrl#DropSensor" ]
enabled indicates whether the sensor is currently paying attention to pointing device input. |
hitPoint the location on the surface of the underlying geometry at which the primary button of the pointing device was released. |
hitNormal the normal at the point given by hitPoint. |
hitTexCoord the texture coordinate at the point given by hitPoint. |
dropTime the time at which the primary button of the pointing device was released. |
nodeChain returns the nodes names from the top-level to the geometry at which the primary button of the pointing device was released. |
url returns the URL for the object (resource) currently dragged to the 3D window. |
Example
#VRML V2.0 utf8 NavigationInfo { type "EXAMINE" } Transform { rotation 1 1 1 1 children [ DEF DS DropSensor {} Shape { geometry Box {} appearance Appearance { texture DEF IT ImageTexture {} material Material { shininess 1 } } } ] } ROUTE DS.url TO IT.url
EventUtilities
These nodes allow authors to handle numerous event-types for interactive scenes without the use of the Script node.
Each node corresponds to standard VRML node. All field definitions are similar to the ISO/IEC 19775 Abstract Specification. This section provides a detailed definition of the syntax of proposed nodes.
BooleanFilter
EXTERNPROTO BooleanFilter [ eventIn SFBool set_boolean eventOut SFBool inputFalse eventOut SFBool inputNegate eventOut SFBool inputTrue ] [ "urn:inet:parallelgraphics.com:cortona:BooleanFilter" "http://www.cortona3d.com/source/extensions.wrl#BooleanFilter" ]
The BooleanFilter node allows routing of boolean values and negation. On receiving the set_boolean TRUE event, the BooleanFilter node generates the inputTrue event, and on receiving FALSE, it generates the inputFalse event. In both cases the BooleanFilter node generates the inputNegate event, which is the negation of the set_boolean value.
BooleanToggle
EXTERNPROTO BooleanToggle [ eventIn SFBool set_boolean exposedField SFBool toggle #FALSE ] [ "urn:inet:parallelgraphics.com:cortona:BooleanToggle" "http://www.cortona3d.com/source/extensions.wrl#BooleanToggle" ]
The BooleanToggle node stores a boolean value in the toggle field and negates it on receiving of the set_boolean TRUE event. The set_boolean FALSE event is ignored.
BooleanTrigger
EXTERNPROTO BooleanTrigger [ eventIn SFTime set_triggerTime eventOut SFBool triggerTrue ] [ "urn:inet:parallelgraphics.com:cortona:BooleanTrigger" "http://www.cortona3d.com/source/extensions.wrl#BooleanTrigger" ]
BooleanTrigger is a node that always generates the triggerTrue TRUE event on receiving a set_triggerTime event.
IntegerSequencer
EXTERNPROTO IntegerSequencer [ eventIn SFBool next eventIn SFBool previous eventIn SFBool set_fraction exposedField MFFloat key #[] (-inf,inf) exposedField MFInt32 keyValue #[] -1|[1,inf) eventOut MFInt32 value_changed ] [ "urn:inet:parallelgraphics.com:cortona:IntegerSequencer" "http://www.cortona3d.com/source/extensions.wrl#IntegerSequencer" ]
The IntegerSequencer node generates the value_changed event on receiving a set_fraction event. The value of the value_changed event is taken from the keyValue array's element corresponding to the element of the key array the value of which equals to the value of the set_fraction event.
IntegerTrigger
EXTERNPROTO IntegerTrigger [ eventIn SFBool set_boolean exposedField SFInt32 integerKey #1 | (-inf,inf) eventOut SFInt32 triggerValue ] [ "urn:inet:parallelgraphics.com:cortona:IntegerTrigger" "http://www.cortona3d.com/source/extensions.wrl#IntegerTrigger" ]
On receiving a set_boolean event, the IntegerTrigger node generates the triggerValue event with the current value of integerKey. This is useful for connecting environmental events to the Switch node's whichChoice.
TimeTrigger
EXTERNPROTO TimeTrigger [ eventIn SFBool set_boolean eventOut SFTime triggerTime ] [ "urn:inet:parallelgraphics.com:cortona:TimeTrigger" "http://www.cortona3d.com/source/extensions.wrl#TimeTrigger" ]
The triggerTime event is generated on receiving a set_boolean event. The value of triggerTime is the time at which set_boolean is received. The value of set_boolean is ignored.
FlashMovie
The FlashMovie node enables you to place Flash animations in your VRML scenes and establish bi-directional interaction between VRML scenes and Flash animations. Flash Player v.4 or later should be installed on your computer.
#VRML V2.0 utf8 EXTERNPROTO FlashMovie [ exposedField SFBool wantMouse # TRUE exposedField SFBool wantKeys # TRUE exposedField SFBool playing # FALSE exposedField SFBool loop # FALSE exposedField SFInt32 quality # 0=Low, 1=High, 2=AutoLow, 3=AutoHigh exposedField SFInt32 scaleMode # 0=ShowAll, 1=NoBorder, 2=ExactFit exposedField SFInt32 alignMode # flags, Left=1, Right=2, Top=4, Bottom=8 exposedField SFInt32 frameNum # 0 exposedField SFInt32 width # 256 exposedField SFInt32 height # 256 exposedField SFColor backgroundColor # [] exposedField MFString url # [] field SFBool repeatS # TRUE field SFBool repeatT # TRUE eventIn SFString command # eventOut SFInt32 readyState # 0=Loading, 1=Uninitialized, # 2=Loaded, 3=Interactive, 4=Complete eventOut SFInt32 totalFrames # eventOut SFInt32 percentLoaded # eventOut MFString fsCommand # ] [ "urn:inet:parallelgraphics.com:cortona:FlashMovie" "http://www.cortona3d.com/source/extensions.wrl#FlashMovie" ]
The key benefits from displaying Flash movies using the FlashMovie node instead of the MovieTexture node:
ability to control the playback of Flash movies from VRML scenes by starting or stopping animations, or by specifying frame numbers; |
direct access from VRML scenes to the basic properties of Flash movies, such as quality and background color of the movie; |
Flash FSCommand actions generate events in VRML scenes. |
The texture field of the Appearance VRML node, and the texture field of the AdvancedAppearance VRML extension node in Cortona, can reference FlashMovie node.
Fields and events:
wantMouse | determines whether the Flash movie can receive mouse events from Cortona window |
wantKeys | determines whether the Flash movie can receive keyboard events from Cortona window |
playing | specifies whether the Flash movie is playing |
loop | specifies whether the Flash movie continues playing into the next cycle at the end of the previous cycle. A Flash movie with loop true at the end of every cycle continues playing forever. |
quality | specifies the level of anti-aliasing to be used during playback of the Flash movie. Values: 0=Low, 1=High, 2=AutoLow, 3=AutoHigh |
scaleMode | determines how the Flash movie is displayed if its size differs from the size specified by the width/height properties. Values: 0=ShowAll, 1=NoBorder, 2=ExactFit |
alignMode | determines how the Flash movie is aligned if its size differs from the size specified by the width/height properties. Values: Left=1, Right=2, Top=4, Bottom=8 |
frameNum | specifies the number of the current frame in the Flash movie (the first frame has a zero number) |
width, height | indicate the width and height of the Flash movie texture in pixels respectively |
backgroundColor | specifies the background color of the Flash movie |
url | defines the URL for the Flash movie file |
repeatS, repeatT | specify how the texture wraps in the S and T directions. They are analogues of repeatS and repeatT fields of the VRML ImageTexture node respectively. |
command | specifies a string which is transferred to the Flash movie. This string can be used for setting values of Flash movie properties and invoking methods which have no parameters. |
readyState | indicates the state of the Flash movie. Values: 0=Loading, 1=Uninitialized, 2=Loaded, 3=Interactive, 4=Complete. |
totalFrames | specifies the total number of frames in the Flash movie. |
percentLoaded | indicates the percentage of the Flash movie loading process. |
fsCommand | specifies MFString strings containing commands generated in the Flash movie. This event value has the following syntax: [command, arg] or [command1, arg1, command2, arg2,...]. For more details see the Controlling the Flash Player entry in the Macromedia Flash help system. |
GradientBackground
The GradientBackground allows for creating horizontal or vertical gradient background that is static relatively to the camera movements.
EXTERNPROTO GradientBackground [ eventIn SFBool set_bind exposedField MFColor color 0,0,0 exposedField MFFloat colorPosition 0 exposedField SFString type "LINEAR-VERTICAL" eventOut SFBool isBound ] [ "urn:inet:parallelgraphics.com:cortona:GradientBackground" "http://www.cortona3d.com/source/extensions.wrl#GradientBackground" ]
The set_bind field works in the same way as the set_bind field of the Background node.
The color field specifies two or more colors of the gradient.
The colorPosition field specifies the positions of colors listed in the color field. If only two colors are used to create the gradient, the colorPosition field is not necessary. If the value of the colorPosition field is not specified, the colors are arranged uniformly.
The type field specifies whether the gradient is horizontal or vertical. The possible values are "LINEAR-VERTICAL" (default) and "LINEAR-HORIZONTAL".
The isBound field works in the same way as the isBound field of the Background node.
Interpolator Nodes in Cortona
The standard VRML interpolator nodes, such as, ColorInterpolator, CoordinateInterpolator, NormalInterpolator, OrientationInterpolator, PositionInterpolator, ScalarInterpolator nodes, and ParallelGraphics Position2Interpolator node are designed for linear keyframed animation among the lists of SFColor, SFVec3f, SFRotation, SFFloat and SFVec2f values. These nodes are used as a base for most simple animations in VRML scenes. The implementation of smooth (non-linear) animations in VRML is possible only with the use of the Script VRML node. Apart from being inconvenient for content creators, this results in significant reduction in performance. If smooth animations are created with the use of linear interpolators, a larger number of keyframes and therefore substantially larger size of files result.
ParallelGraphics VRML extension nodes were introduced to resolve this problem by extending the capabilities of existing interpolator nodes of the corresponding types. By setting the value of the type field of the new interpolator nodes, the content creator can choose the desired type of interpolation - how the values of a parameter should be generated between keyframe values. Specifying non-linear interpolation types allows developers to create smooth and realistic animations with the use of a minimum number of keyframes.
All the new ParallelGraphics interpolator nodes, except for the OrientationInterpolatorEx node, share the following common set of fields and semantics:
eventIn | SFFloat | set_fraction | |
exposedField | MFFloat | key | [...] |
exposedField | MF<type> | keyValue | [...] |
eventOut | SF<type> | value_changed | |
exposedField | SFString | type | "LINEAR" |
exposedField | MFFloat | params | [0, 0, 0] # (-inf,inf) |
The type field specifies the type of interpolation used. The following values of this field are possible: "CONSTANT", "LINEAR", "COSINE", "CUBIC" and "HERMITE":
Interpolation | |
"CONSTANT" | The value remains fixed until the next keyframe. No interpolation is performed. |
"LINEAR" | The value changes linearly from the previous to the next keyframe value. For complex values, each of the components changes independently of other components. The speed of the value change (acceleration or deceleration) is constant throughout the interval. This is how interpolation is performed by standard VRML interpolator nodes which the corresponding ParallelGraphics interpolator nodes extend. |
"COSINE" | The value changes according to the cosine law in the interval between the previous and the next keyframe values. The speed of the value change is minimum (zero) both at the beginning and end of the interval while the maximum speed of the value change is achieved in the middle of the interval. |
"CUBIC" | The value changes between keyframes values according to cubic law. Cubic splines provide quick and smooth interpolation of values. |
"HERMITE" | The Kochanek-Bartels splines (also known as TCB splines), which are based on Hermite polynoms, provide cubic interpolation of the parameter between keyframes values. The exact type of dependence between the values of a key and the corresponding keyValue parameter (interpolation function) can be customized using three TCB-splines parameters specified by the params field. |
Notes (for "CUBIC" and "HERMITE" interpolation types):
Linear interpolation is used instead of cubic interpolation if the number of keyframes is less than 4. |
If the value of the first keyframe coincides with the value of the last keyframe, the cubic spline is "closed", i.e. there is no derivative hit of keyValue when interpolating between the last and first keyframes. |
Three values in the params field of the interpolator nodes with extended capabilities specify the parameters of Kochanek-Bartels splines which customize the interpolation function:
Parameter | Name | Description |
0 | Tension | Specifies the bending sharpness of the interpolation function at keyframes (higher tension values correspond to tighter function curves, lower - to looser curves). |
1 | Continuity | Specifies the variation in derivative of the interpolation function from the left and right at keyframes (zero - transition between adjacent intervals at keyframes is smooth, non-zero - intersections of intervals are abrupt). |
2 | Bias | Controls the amount that the interpolation function bends at each end of the interval between keyframes (Bias<0 - the function bends more at the beginning of the interval, Bias>0 - the function bends more at the end). |
Note: if the values of the Continuity and Bias parameters are equal to 0, the Kochanek-Bartels splines are identical to cardinal splines. If all three parameters are equal to zero (the default value of the params field), the TSB splines are identical to the Catmull-Rom splines.
The OrientationInterpolatorEx node has only one additional field - type. This field can take on the following values: "CONSTANT", "LINEAR" (slerp) and "SPLINE" (squad) that specify constant, linear and cubic spline interpolation respectively.
Definitions of the other fields and events in the interpolator nodes are similar to the definitions of the corresponding standard VRML nodes. More information about interpolators in VRML is available at the Interpolators nodes topic in the VRML97 Specification.
ColorInterpolatorEx
The ColorInterpolatorEx node interpolates among a list of MFColor values using a specified interpolation method. This node extends the standard ColorInterpolator VRML node.
EXTERNPROTO ColorInterpolatorEx [ eventIn SFFloat set_fraction # (-inf,inf) exposedField MFFloat key [] # (-inf,inf) exposedField MFColor keyValue [] # [0,1] exposedField MFFloat params [0, 0, 0] # (-inf,inf) exposedField SFString type "LINEAR" eventOut SFColor value_changed ] [ "urn:inet:parallelgraphics.com:cortona:Position2Interpolator" "http://www.cortona3d.com/source/extensions.wrl#ColorInterpolatorEx" ]
The type field defines the interpolation method. The possible values of this field are "CONSTANT", "LINEAR", "COSINE", "CUBIC" and "HERMITE". In the case of the Hermite interpolation, the params field specifies three interpolation parameters: Tension, Continuity and Bias.
Definitions of the other fields and events of the ColorInterpolatorEx node are similar to the corresponding definitions for the ColorInterpolator VRML node.
OrientationInterpolatorEx
The OrientationInterpolatorEx node interpolates among a list of rotation values using a specified interpolation method. This node extends the standard OrientationInterpolator node.
EXTERNPROTO OrientationInterpolatorEx [ eventIn SFFloat set_fraction # (-inf,inf) exposedField MFFloat key [] # (-inf,inf) exposedField MFRotation keyValue [] # [-1,1],(-inf,inf) exposedField SFString type "LINEAR" eventOut SFRotation value_changed ] [ "urn:inet:parallelgraphics.com:cortona:OrientationInterpolatorEx" "http://www.cortona3d.com/source/extensions.wrl#OrientationInterpolatorEx" ]
The type field defines the interpolation method. The possible values of this field are "CONSTANT", "LINEAR" (slerp) and "SPLINE" (squad):
Interpolation | |
"CONSTANT" | The orientation value remains fixed until the next keyframe. No interpolation is performed. |
"LINEAR" | The value of orientation is interpolated uniformly along a geodesic in the surface of the 3-sphere between the previous and the next keyframe values. This method is often referred to as SLERP (Spherical-Linear intERPolation). That is how the interpolation is made by the OrientationInterpolator node. |
"SPLINE" | The value of orientation is interpolated between keyframe values using cubic Hermite polynoms. This method is referred to as SQUAD (Spherical QUADrilateral interpolation). Unlike SLERP, the transition between adjacent intervals at keyframes is smooth. |
Notes (for the "SPLINE" interpolation type):
Linear interpolation is used instead of cubic interpolation if the number of keyframes is less than 4. |
If the value of the first keyframe coincides with the value of the last keyframe, the cubic spline is "closed". |
Definitions of the other fields and events of the OrientationInterpolatorEx node are similar to the corresponding definitions for the OrientationInterpolator node.
PositionInterpolator2DEx
The PositionInterpolator2DEx node interpolates among a list of SFVec2f values using a specified interpolation method. This node extends the ParallelGraphics extension node Position2Interpolator.
EXTERNPROTO PositionInterpolator2DEx [ eventIn SFFloat set_fraction # (-inf,inf) exposedField MFFloat key [] # (-inf,inf) exposedField MFVec2f keyValue [] # (-inf,inf) exposedField MFFloat params [0, 0, 0] # (-inf,inf) exposedField SFString type "LINEAR" eventOut SFVec2f value_changed ] [ "urn:inet:parallelgraphics.com:cortona:PositionInterpolator2DEx" "http://www.cortona3d.com/source/extensions.wrl#PositionInterpolator2DEx" ]
The type field defines the interpolation method. The possible values of this field are "CONSTANT", "LINEAR", "COSINE", "CUBIC" and "HERMITE". In the case of the Hermite interpolation, the params field specifies three interpolation parameters: Tension, Continuity and Bias.
Definitions of the other fields and events of the PositionInterpolator2DEx node are similar to the corresponding definitions for the ParallelGraphics extension node Position2Interpolator.
PositionInterpolatorEx
The PositionInterpolatorEx node interpolates among a list of 3D vectors using a specified interpolation method. This node extends the standard PositionInterpolator VRML node.
EXTERNPROTO PositionInterpolatorEx [ eventIn SFFloat set_fraction # (-inf,inf) exposedField MFFloat key [] # (-inf,inf) exposedField MFVec3f keyValue [] # (-inf,inf) exposedField MFFloat params [0, 0, 0] # (-inf,inf) exposedField SFString type "LINEAR" eventOut SFVec3f value_changed ] [ "urn:inet:parallelgraphics.com:cortona:PositionInterpolatorEx" "http://www.cortona3d.com/source/extensions.wrl#PositionInterpolatorEx" ]
The type field defines the interpolation method. The possible values of this field are "CONSTANT", "LINEAR", "COSINE", "CUBIC" and "HERMITE". In the case of the Hermite interpolation, the params field specifies three interpolation parameters: Tension, Continuity and Bias.
Definitions of the other fields and events of the ColorInterpolatorEx node are similar to the corresponding definitions for the PositionInterpolator VRML node.
Position2Interpolator
The Position2Interpolator node linearly interpolates among a list of 2D vectors. This node allows a dynamic transformation that is applied to texture coordinates without implementation of the Script node.
Node description
EXTERNPROTO Position2Interpolator [ eventIn SFFloat set_fraction exposedField MFFloat key [] exposedField MFVec2f keyValue [] eventOut SFVec2f value_changed ] [ "urn:inet:parallelgraphics.com:cortona:Position2Interpolator" "http://www.cortona3d.com/source/extensions.wrl#Position2Interpolator" ]
All definitions of the fields are similar to the VRML97 definitions of the PositionInterpolator node.
Example
#VRML V2.0 utf8 NavigationInfo { type "EXAMINE" } Transform { rotation 1 1 1 1 children [ Shape { geometry Box {} appearance Appearance { texture ImageTexture { url "sky01.gif" } textureTransform DEF TT TextureTransform {} } } ] } DEF TIS TimeSensor { loop TRUE cycleInterval 5 } DEF PI2 Position2Interpolator { key [0 1] keyValue [0 0, 1 1] } ROUTE TIS.fraction_changed TO PI2.set_fraction ROUTE PI2.value_changed TO TT.translation
ScalarInterpolatorEx
The ScalarInterpolatorEx node interpolates among a list of SFFloat values using a specified interpolation method. This node extends the standard ScalarInterpolator VRML node.
EXTERNPROTO ScalarInterpolatorEx [ eventIn SFFloat set_fraction # (-inf,inf) exposedField MFFloat key [] # (-inf,inf) exposedField MFFloat keyValue [] # (-inf,inf) exposedField MFFloat params [0, 0, 0] # (-inf,inf) exposedField SFString type "LINEAR" eventOut SFFloat value_changed ] [ "urn:inet:parallelgraphics.com:cortona:ScalarInterpolatorEx" "http://www.cortona3d.com/source/extensions.wrl#ScalarInterpolatorEx" ]
The type field defines the interpolation method. The possible values of this field are "CONSTANT", "LINEAR", "COSINE", "CUBIC" and "HERMITE". In the case of the Hermite interpolation, the params field specifies three interpolation parameters: Tension, Continuity and Bias.
Definitions of the other fields and events of the ScalarInterpolatorEx node are similar to the corresponding definitions for the ScalarInterpolator VRML node.
KbdSensor
The KbdSensor node generates events based on input from a keyboard.
Node description
EXTERNPROTO KbdSensor [ exposedField SFBool enabled TRUE exposedField SFBool isActive FALSE eventOut SFInt32 keyDown eventOut SFInt32 keyUp ] [ "urn:inet:parallelgraphics.com:cortona:KbdSensor" "http://www.cortona3d.com/source/extensions.wrl#KbdSensor" ]
enabled indicates whether the sensor is currently paying attention to a keyboard input. If enabled receives TRUE and isActive is TRUE, the sensor reacts on input from a keyboard. In this case, the user cannot navigate in the 3D window using keyboard commands. |
isActive allows to control the sensor. If isActive receives a TRUE event, the sensor processes all keyboard input. Otherwise, the input is treated with a browser. |
keyDown and keyUp events generate 32-bit value containing the character code of the key that was pressed or released. The primary two bytes specify the virtual-key code of the nonsystem key, and the secondary - key-state flags. |
Example
#VRML V2.0 utf8 NavigationInfo { type "EXAMINE" } Background { skyColor [1 1 1] } DEF KS KbdSensor { isActive TRUE } Shape { geometry DEF TXT Text { string ["?"] fontStyle FontStyle { justify ["MIDDLE", "MIDDLE"] family "TYPEWRITER" style "BOLD" size 4 } } appearance Appearance { material Material { diffuseColor 0.02 0.38 0.61 } } } DEF SCR Script { directOutput TRUE eventIn SFInt32 go field SFNode TXT USE TXT field MFString string [""] url ["javascript: function go(val,ts){ string[0]= String.fromCharCode(val.toString()); TXT.string=string; } "] } ROUTE KS.keyDown TO SCR.go
Layers and 2D Nodes
Layers
Layers are transparent rectangular areas on the screen in which VRML scenes are rendered. These areas always face the viewer.
Layer2D
EXTERNPROTO Layer2D [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField MFNode children NULL exposedField SFVec2f size -1, -1 exposedField SFNode background NULL ] [ "urn:inet:parallelgraphics.com:cortona:Layer2D" "http://www.cortona3d.com/source/extensions.wrl#Layer2D" ]
The Layer2D node represents an area where 2D scene is rendered.
Its coordinate system's origin is positioned in the center of the rendering area, the x-axis is positive to the right and y-axis in positive upwards.
The width of the rendering area represents -1.0 to +1.0 on the x-axis. The extent of the y-axis in the positive and negative directions is determined by the aspect ratio of the rendering area so that the unit of distance is equal in both directions.
The children field may contain any 2D nodes. The addChildren and removeChildren fields are lists of 2D nodes to add and, respectively, remove from the layer.
The size parameter specifies width and height of layer rectangle in local coordinate system.
The background field specifies the Background of the current layer. It may only contain Background2D node.
Layer3D
EXTERNPROTO Layer3D [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField MFNode children NULL exposedField SFVec2f size -1, -1 exposedField SFNode background NULL exposedField SFNode fog NULL exposedField SFNode navigationInfo NULL exposedField SFNode viewpoint NULL ] [ "urn:inet:parallelgraphics.com:cortona:Layer3D" "http://www.cortona3d.com/source/extensions.wrl#Layer3D" ]
The Layer3D node represents an area where 3D scene is rendered. Its coordinate system is the same as used in VRML scene.
The children field may contain any 3D nodes. The addChildren and removeChildren fields are lists of 3D nodes to add and, respectively, remove from the layer.
The size parameter specifies width and height of layer rectangle in local coordinate system.
The background field specifies the Background of the current layer. It may only contain Background node.
The fog field specifies the Fog node.
The navigationInfo field specifies the NavigationInfo node.
The viewpoint field specifies the Viewpoint node.
2D Nodes
2D geometry nodes specify the planar type of geometry nodes. All 2D geometry nodes are used in the two-dimensional coordinate system. The origin and direction of x- and y-axes in the 2D coordinate system coincides with the origin and direction of x- and y-axes in the 3D coordinate system correspondingly. Z-component is set to null (z=0). As 2D geometry nodes come from geometry component they are defined in the geometry field of the Shape node. As all geometry nodes, 2D geometry nodes are affected by the Appearance node, which describes by the appearance properties (material and texture) that is applied to the geometry. Only emissivecolor and transparency of the Material properties are applied to 2D geometry, other properties have no effect.
2D geometry is mainly implemented (designed) for use in Layer2D nodes.
Circle
EXTERNPROTO Circle [ field SFFloat radius #1 (0,inf) ] [ "urn:inet:parallelgraphics.com:cortona:Circle" "http://www.cortona3d.com/source/extensions.wrl#Circle" ]
The Circle node specifies a circle centered at (0,0) in the local 2D coordinate system. The radius field specifies the radius of the Circle. The value of radius should be greater than zero.
Rectangle
EXTERNPROTO Rectangle [ field SFVec2f size #2 2 (0,inf) ] [ "urn:inet:parallelgraphics.com:cortona:Rectangle" "http://www.cortona3d.com/source/extensions.wrl#Rectangle" ]
The Rectangle node specifies a rectangle centered at (0, 0) in the current local 2D coordinate system and aligned with the local coordinate axes. The size field specifies the values of the rectangle's sides. Each component value should be greater than zero.
IndexedLineSet2D
EXTERNPROTO IndexedLineSet2D [ eventIn MFInt32 set_colorIndex eventIn MFInt32 set_coordIndex exposedField SFNode color #NULL exposedField SFNode coord #NULL field MFInt32 colorIndex #[] field SFBool colorPerVertex #TRUE field MFInt32 coordIndex #[] ] [ "urn:inet:parallelgraphics.com:cortona:IndexedLineSet2D" "http://www.cortona3d.com/source/extensions.wrl#IndexedLineSet2D" ]
The IndexedLineSet2D represents a 2D shape consisting of 2D lines. The coord field contains the Coordinate2D node that specifies coordinates of the vertices, from which lines are formed. IndexedFaceSet2D is a 2D equivalent of the IndexedLineSet node.
IndexedFaceSet2D
EXTERNPROTO IndexedFaceSet2D [ eventIn MFInt32 set_colorIndex eventIn MFInt32 set_coordIndex eventIn MFInt32 set_texCoordIndex exposedField SFNode color #NULL exposedField SFNode coord #NULL exposedField SFNode texCoord #NULL field MFInt32 colorIndex #[] field SFBool colorPerVertex #TRUE field SFBool convex #TRUE field MFInt32 coordIndex #[] field MFInt32 texCoordIndex #[] ] [ "urn:inet:parallelgraphics.com:cortona:IndexedFaceSet2D" "http://www.cortona3d.com/source/extensions.wrl#IndexedFaceSet2D" ]
The IndexedFaceSet2D represents a 2D shape consisting of 2D faces. The coord field contains the Coordinate2D node that specifies coordinates of the vertices from which faces are formed. IndexedFaceSet2D is a 2D equivalent of the IndexedFaceSet node.
PointSet2D
EXTERNPROTO PointSet2D [ exposedField SFNode color #NULL exposedField SFNode coord #NULL ] [ "urn:inet:parallelgraphics.com:cortona:PointSet2D" "http://www.cortona3d.com/source/extensions.wrl#PointSet2D" ]
The PointSet2D node specifies a set of 2D points. The coord field contains the Coordinate2D node. The PointSet2D node is a 2D equivalent of the PointSet node.
Coordinate2D
EXTERNPROTO Coordinate2D [ exposedField MFVec2f point #[] ] [ "urn:inet:parallelgraphics.com:cortona:Coordinate2D" "http://www.cortona3d.com/source/extensions.wrl#Coordinate2D" ]
The Coordinate2D node specifies a set of 2D coordinates, which is used in the coord field of PointSet2D, IndexedLineSet2D and IndexedFaceSet2D nodes.
CoordinateInterpolator2D
EXTERNPROTO CoordinateInterpolator2D [ eventIn SFFloat set_fraction exposedField MFFloat key #[] exposedField MFVec2f keyValue #[] eventOut MFVec2f value_changed ] [ "urn:inet:parallelgraphics.com:cortona:CoordinateInterpolator2D" "http://www.cortona3d.com/source/extensions.wrl#CoordinateInterpolator2D" ]
The CoordinateInterpolator2D node is the 2D equivalent of the CoordinateInterpolator node.
Transform2D
EXTERNPROTO Transform2D [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField SFVec2f center #0,0 exposedField MFNode children #[] exposedField SFFloat rotationAngle #0.0 exposedField SFVec2f scale #1,1 exposedField SFFloat scaleOrientation #0.0 exposedField SFVec2f translation #0,0 ] [ "urn:inet:parallelgraphics.com:cortona:Transform2D" "http://www.cortona3d.com/source/extensions.wrl#Transform2D" ]
The Transform2D node is a 2D equivalent of the Transform node. It is a grouping node that allows translation, rotation and scaling of its 2D children. The translation field specifies translation of the children objects. The rotationAngle field specifies rotation of the children objects. The centre of rotation is the point specified in the center field. The scale field specifies scaling of the children nodes. The scaleOrientation specifies a rotation of the coordinate system before the scale (to specify scales in arbitrary orientations). The scaleOrientation field applies only to the scale operation.
Transform2DEx
The Transform2DEx node allows for positioning layers on the screen and specifying their size in pixels.
Note: The Transform2DEx node should not be used inside Transform and Layer nodes.
EXTERNPROTO Transform2DEx [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField SFVec2f center #0,0 exposedField MFNode children #[] exposedField SFFloat rotationAngle #0.0 exposedField SFVec2f scale #1,1 exposedField SFFloat scaleOrientation #0.0 exposedField SFVec2f translation #0,0 exposedField SFVec2f origin #0,0 exposedField SFVec2f pixelTranslation #0,0 exposedField SFVec2f pixelScale #0,0 ] [ "urn:inet:parallelgraphics.com:cortona:Transform2DEx" "http://www.cortona3d.com/source/extensions.wrl#Transform2DEx" ]
The Transform2DEx node is a equivalent of the Transform2D node. It is a grouping node that allows translation, rotation and scaling of its 2D children.
The translation field specifies translation of the children objects.
The rotationAngle field specifies rotation of the children objects.
The centre of rotation is the point specified in the center field.
The scale field specifies scaling of the children nodes.
The scaleOrientation specifies a rotation of the coordinate system before the scale (to specify scales in arbitrary orientations). The scaleOrientation field applies only to the scale operation.
The origin field specifies the translation of coordinate system.
The pixelTranslation field specifies translation of the children objects in pixels.
The pixelScale field specifies scaling of the children objects in pixels.
Background2D
EXTERNPROTO Background2D [ eventIn SFBool set_bind exposedField SFColor backColor #0 0 0 exposedField MFString url #[] eventOut SFBool isBound ] [ "urn:inet:parallelgraphics.com:cortona:Background2D" "http://www.cortona3d.com/source/extensions.wrl#Background2D" ]
Background2D node is a 2D equivalent of the Background node. Background2D is used only in 2D context, such as Layer2D node.
backColor field specifies the color of the of the background. url field specifies an image which is applied to the 2D background.
As there is no background stack in the layer nodes, set_bind and isBound fields are ignored.
MipMap
The MipMap node specifies a set of texture nodes containing low- and high-resolution versions of the same texture to be used for texturing geometry.
EXTERNPROTO MipMap [ exposedField MFNode levels ] [ "urn:inet:parallelgraphics.com:cortona:MipMap" "http://www.cortona3d.com/source/extensions.wrl#MipMap" ]
Fields and events
levels Contains a set of texture nodes (ImageTexture, PixelTexture, or MovieTexture), which specify different mip-map levels for an original texture. The original (most detailed) texture should be referenced in the first position of the levels field (level zero mip-map). Every next texture referenced by this field should have dimension (by each of the sizes) two times less than the previous texture and have the same format. Otherwise, the next texture is stretched to the required size and converted to the required format. If any of the levels is missing, it is generated automatically. |
The use of mip-maped textures of different levels reduces the jagged effect (this effect is observed when the scene contains acutely angled polygons that disappear into the distance).
In most cases, it is recommended to use automatic mip-mapping that can be enabled through the Use textures mip-mapping renderer option in Cortona. If automatic mip-mapping does not give the desired effect, the MipMap node should be used.
NurbsSurface
NURBS in Cortona
Extending VRML standard ParallelGraphics realized support of a mathematical model for surfaces known as NURBS for Cortona VRML client 1.5+. With NURBS geometry, users can model complex sculptured shapes faster, more accurately, and with fewer surfaces. For example, NURBS geometry makes it possible to treat the hood of an automobile or the wing of an airplane as a single surface and create more realistic shapes of human bodies. With NURBS it is easier to create virtual worlds in VRML with smooth surfaces and reduced download size of VRML files because of the compact NURBS description at once. |
Geometric NURBS node
This description corresponds to NURBS Extension for VRML97 Discussion & Node proposal 12 March, 1999 by Blaxxun interactive except the fields distance, quality, uTessellation, vTessellation, and texCoord.
NurbsSurface { field SFInt32 uDimension 0 #[0, inf) field SFInt32 vDimension 0 #[0, inf) field MFFloat uKnot [] #(-inf,inf) field MFFloat vKnot [] #[2, inf) field SFInt32 uOrder 3 #[2, inf) field SFInt32 vOrder 3 #[2, inf) exposedField MFVec3f controlPoint [] #(-inf,inf) exposedField MFFloat weight [] #(0, inf) exposedField SFInt32 uTessellation 0 #(-inf,inf) exposedField SFInt32 vTessellation 0 #(-inf,inf) exposedField SFNode texCoord [] exposedField SFBool ccw TRUE exposedField SFBool solid TRUE exposedField MFFloat distance 10 exposedField MFFloat quality [0, 0.75] }
uDimension and vDimension define the number of control points in the u and v dimensions. |
uOrder and vOrder define the order of surface. From a mathematical point of view, the surface is defined by polynomials of the degree order-1.
The order of the curves uOrder and vOrder must be greater or equal to 2. An implementation may limit uOrder and vOrder to a certain number. The most common orders are 3 (quadratic polynomial) and 4 (cubic polynomial), which are sufficient to achieve the desired curvature in most cases. |
controlPoint defines a set of control points of dimension uDimension * vDimension. This set of points defines a mesh similar to the grid of an ElevationGrid whereas the points do not have a uniform spacing. Depending on the weight-values and the order this hull is approximated by the resulting surface. uDimension points define a polyline in u-direction followed by further u-polylines with the v-parameter in ascending order. The number of control points must be equal or greater than the order. A closed B-Spline surface can be specified by repeating the limiting control points.
The control vertex corresponding to the control point P[i, j] on the control grid is : P[i,j].x = controlPoints[i + (j * uDimension)].x P[i,j].y = controlPoints[i + (j * uDimension)].y P[i,j].z = controlPoints[i + (j * uDimension)].z P[i,j].w = weight[ i + (j * uDimension)] where 0 <= i < uDimension and 0 <= j < vDimension. |
A weight value that must be greater than zero is assigned to each controlPoint. The ordering of the values is equivalent to the ordering of the control point values. If the weight of a control point increased above 1 the point is closer approximated by the surface. The number of values must be identical to the number of control points. If the length of the weight vector is 0, the default weight 1.0 is assumed for each control point. |
uKnots and vKnots define the knot vector. The number of knots must be equal to the number of control points plus the order of the curve. The order must be non-decreasing. By setting successive knot values equal the degree of continuity is decreased, which implies that the surface gets edges. If k is the order of the curve, k consecutive knots at the end or the beginning of the vector let converge the curve to the last or the first control point respectively. Within the knot vector there may be not more than k-1 consecutive knots of equal value. If the length of a knot vector is 0, a default uniform knot vector is computed. |
uTessellation and vTessellation are ignored by Cortona (used for the compatibility with blaxxun Contact). |
texCoord could provide additional information on how to generate texture coordinates. By default, texture coordinates in the unit square are generated automatically from the parametric subdivision. The texCoord field specifies per-vertex texture coordinates for the NurbsSurface node. If texCoord is not NULL, it shall specify a TextureCoordinate node containing (uDimension)x(vDimension) texture coordinates; one for each control point, ordered according to a set of control points. The texture coordinates for each point of the NURBS surface are calculated the same way as ordinary coordinates, but the array from TextureCoordinate is used instead of controlPoint. |
ccw and solid are defined like in other VRML Geometry nodes. solid TRUE enables two-sided lighting, the surface is visible from both sides, and normals are flipped toward the viewer, prior to shading. |
The distance and quality fields enable to control the quality of the NURBS surface breake down (triangulation) depending on the distance from the camera to the center of the object bounding box. The distance field specifies a set of distances to object. Each distance[i] value is correspond to the quality[i+1] value. The quality[0] value specifies the triangulation quality at distance=0. Thus, if the greatest index in the distance field is N, there shall be N+1 qualities in the quality field. D <= distance[0]: Q = quality[0] + (quality[1] - quality[0]) * D / distance[0] distance[i] < D <= distance[i+1]: Q = quality[i+1] + (quality[i+2] - quality[i+1]) * (D - distance[i]) / (distance[i+1] - distance[i]) distance[N-1] < D: Q = quality[N], where: |
OrderedGroup
EXTERNPROTO OrderedGroup [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField MFNode children #[] exposedField MFFloat order #[] ] [ "urn:inet:parallelgraphics.com:cortona:OrderedGroup" "http://www.cortona3d.com/source/extensions.wrl#OrderedGroup" ]
OrderedGroup node is a grouping node which allows to set the order of the rendering of the coplanar or close shapes.
As in all grouping nodes, children field specifies a list of children nodes of the OrderedGroup node, addChildren and removeChildren fields specify the list of objects that shall be added or, respectively, removed from the OrderedGroup node.
order field is an array of floating point numbers. Each value of the order field corresponds to one child from the children field. The child that has the lowest order value is rendered first. Other children are rendered in increasing order. The last rendered child is a child with the highest order value. If the order field is empty, all the children of the OrderedGroup are rendered in the order, that is specified in the children field, from the first to the last.
Panel
EXTERNPROTO Panel [ exposedField SFNode source #NULL exposedField SFString left #"0" exposedField SFString top #"0" exposedField SFString right #"" exposedField SFString bottom #"" exposedField SFString width #"" exposedField SFString height #"" exposedField SFString offsetLeft #"" exposedField SFString offsetTop #"" exposedField SFBool sticky #FALSE exposedField SFBool enabled #FALSE exposedField SFFloat backgroundTransparency #1 exposedField SFColor backgroundColor #1 1 1 exposedField SFInt32 borderSize #0 exposedField SFColor borderColor #1 1 1 eventOut MFInt32 contentSize eventOut SFTime touchTime eventOut SFVec2f touchPoint eventOut SFString hotspot eventOut SFTime hotspotTime ] [ "urn:inet:parallelgraphics.com:cortona:Panel" "http://www.cortona3d.com/source/extensions.wrl#Panel" ]
The Panel node represents a rectangular area where HTML text can be rendered. This area always faces the viewer.
The source field contains an HTMLText node or NULL.
The left, to, right and bottom fields specify panel coordinates. Each coordinate can be specified in pixels, in percents of width (for the left or right fields) or height (for the top or bottom) of 3D window size or can be omitted.
The width and height fields specify the width and height of the panel correspondingly. Width and height can be specified in pixels, in percents of 3D window size or can be omitted.
The offsetLeft and offsetTop fields specify the offset of the panel's content. offsetLeft, offsetTop can be specified in pixels, in percents of panel's size or can be omitted.
The sticky field specifies if the parent coordinate system is used or not. TRUE value means that left, right, top and bottom are ignored and upper left corner of the panel is positioned at the origin of the parent transform.
The enabled field specifies if mouse events are processed or not. FALSE value means that no mouse events are processed; TRUE value means that all mouse events are processed.
The backgroundTransparency field specifies the transparency of the panel's background.
The backgroundColor field specifies the color of the panel's background.
The borderSize field specifies the size of the panel's border.
The borderColor field specifies the color of the panel's border.
The contentSize event is generated if the size of the panel is changed. ContentSize event value contains the size of the panel in pixels.
The touchTime and TouchPoint events. If enabled filed is set to TRUE, TouchTime and TouchPoint events are generated when user clicks on the panel's area.
The hotspot and hotspotTime events. If enabled filed is set to TRUE, hotspot and hotspotTime events are generated when user clicks on the <a href=""></a> tag. Hotspot contains the href of the corresponding <a> tag value.
HTMLText
EXTERNPROTO HTMLText [ exposedField SFString body #"" exposedField MFInt32 padding #[] exposedField SFBool shadow #FALSE exposedField SFFloat shadowTransparency #0 exposedField SFInt32 shadowSize #8 exposedField MFInt32 shadowOffset #[] exposedField SFColor shadowColor #0 0 0 ] [ "urn:inet:parallelgraphics.com:cortona:HTMLText" "http://www.cortona3d.com/source/extensions.wrl#HTMLText" ]
The HTMLText node represents an HTML text, which can be used in the Panel node. The Body field contains a string of HTML code. Only p, a, font, b (strong), i (em), u, br, center tags with the face, size, color attributes are supported.
The padding field specifies padding in pixels in a form of [top [right [bottom [left]]]].
The Shadow field specifies if shadow is used or not. FALSE value means that no shadow is used, TRUE value means that shadow is used.
The ShadowTransparency field specifies the transparency of the shadow.
The ShadowSize field specifies the size of the shadow.
The ShadowOffset field specifies the shadow's offset.
The ShadowColor field specifies the shadow's color.
SphereEnvironment
The SphereEnvironment node specifies a spherical environment map for simulating reflections on 3D objects in the scene.
EXTERNPROTO SphereEnvironment [ exposedField SFNode texture ] [ "urn:inet:parallelgraphics.com:cortona:SphereEnvironment" "http://www.cortona3d.com/source/extensions.wrl#SphereEnvironment" ]
Fields and events
texture Specifies texture of a reflecting shape. Can be ImageTexture, PixelTexture, MovieTexture, BumpMap, or MipMap node. It is not possible to use the BumpMap or MipMap nodes as values of the fields if the SphereEnvironment node is in its turn specified in one of these two nodes. |
During the viewer's motion around the 3D object distortions or other artifacts in the reflection can take place. These problems can be resolved with the use of the cube environmental mapping.
Splines
Cortona spline technology
ParallelGraphics developed spline representation of geometry objects. Typically, by using VRML97 file format, the faces are used to build curvy shapes. There are two choices to avoid faceted shading: use many more faces to approximate the smooth shape, or shade the faces differently so it looks like you used lots of faces (Gouraud method). However, the spline objects are geometrically smooth and allow to transform them to any required quantity of faces to display.
The key benefits from the use of spline objects include:
The high quality of a smooth surface can be described using VRML. |
It is required less computing resources for achievement of high quality. |
The size of the VRML-file decreases essentially (up to 10 times) without degradation of surface quality. |
The smooth variation of input parameters results in transformation of the spline surface that is worth to simplify the creation of realistic animations. |
The dynamic detailed elaboration provides the balance between necessary quality and frame-rate. |
The function of quality allows to operate a degree of detailed elaboration of a surface. |
ParallelGraphics offers six new nodes (SplineCone, SplineCylinder, SplineElevationGrid, SplineExtrusion, SplineFaceSet, SplineSphere) based on the standard nodes and expressed in using the VRML prototyping mechanism (external prototypes). Each new node contains both the same fields standard VRML node includes and extensions controlling level of detailed elaboration of a surface. ParallelGraphics' Cortona VRML client supports the proposed nodes and uses the spline representation for objects. The simplest way to use spline nodes is that of changing the appropriate node name. Other browsers interprets these nodes as Cone, Cylinder, ElevationGrid, Extrusion, FaceSet, and Sphere.
The method of spline representation of geometry objects is based on three-cubic spline interpolation, which is performed with Cortona VRML client automatically using incoming polygonal data (control vertices). So a spline surface includes all control vertices of the polygonal model. While rendering, a surface is broken down (tessellated) into a set of triangles approximating the spline surface. To balance between quality and the frame-rate, a surface curvature and number of triangles are taken into account. Moreover, it's possible to control the tessellation using the quality function.
ParallelGraphics has also developed the suitable converter for the translation of standard polygonal objects to the spline analogies.
Geometric spline nodes
Each node corresponds to standard VRML node except the fields distance and quality. All other field definitions are similar to the VRML97 Node Reference. This section provides a detailed definition of the syntax of proposed nodes.
SplineCone { field SFFloat bottomRadius 1 field SFFloat height 2 field SFBool side TRUE field SFBool bottom TRUE field MFFloat distance 10 field MFFloat quality [0, 0.75] }
SplineCylinder { field SFBool bottom TRUE field SFFloat height 2 field SFFloat radius 1 field SFBool side TRUE field SFBool top TRUE exposedField MFFloat distance 10 exposedField MFFloat quality [0, 0.75] }
SplineElevationGrid { eventIn MFFloat set_height exposedField SFNode color NULL exposedField SFNode normal NULL exposedField SFNode texCoord NULL field MFFloat height [] field SFBool ccw TRUE field SFBool colorPerVertex TRUE field SFFloat creaseAngle 0 field SFBool normalPerVertex TRUE field SFBool solid TRUE field SFInt32 xDimension 0 field SFFloat xSpacing 0.0 field SFInt32 zDimension 0 field SFFloat zSpacing 0.0 exposedField MFFloat distance 10 exposedField MFFloat quality [0, 0.75] }
SplineExtrusion { eventIn MFVec2f set_crossSection eventIn MFRotation set_orientation eventIn MFVec2f set_scale eventIn MFVec3f set_spine field SFBool beginCap TRUE field SFBool ccw TRUE field SFBool convex TRUE field SFFloat creaseAngle 0 field MFVec2f crossSection [1 1, 1 -1, -1 -1, -1 1, 1 1] field SFBool endCap TRUE field MFRotation orientation 0 0 1 0 field MFVec2f scale 1 1 field SFBool solid TRUE field MFVec3f spine [0 0 0, 0 1 0] field MFFloat distance 10 field MFFloat quality [0, 0.75] }
SplineFaceSet { eventIn MFInt32 set_colorIndex eventIn MFInt32 set_coordIndex eventIn MFInt32 set_normalIndex eventIn MFInt32 set_texCoordIndex exposedField SFNode color NULL exposedField SFNode coord NULL exposedField SFNode normal NULL exposedField SFNode texCoord NULL field SFBool ccw TRUE field MFInt32 colorIndex [] field SFBool colorPerVertex TRUE field SFBool convex TRUE field MFInt32 coordIndex [] field SFFloat creaseAngle 0 field MFInt32 normalIndex [] field SFBool normalPerVertex TRUE field SFBool solid TRUE field MFInt32 texCoordIndex [] exposedField MFFloat distance 10 exposedField MFFloat quality [0, 0.75] }
SplineSphere { field SFFloat radius 1 exposedField MFFloat distance 10 exposedField MFFloat quality [0, 0.75] }
The smoothing surfaces is available only if the field normalPerVertex is set to TRUE (default value) that is correspond to Gouraud method for polygonal objects. If a set of 3D surface normal vectors is defind in node(the normal field), Cortona will use it in generating of a spline surface. If the normal field is NULL, the browser treats the normals automatically generated, using the creaseAngle field (see VRML97, Node Reference). The resulted spline surface contains all of vertices defined in node, and normals per vertex coincide with normals per spline surface at vertices.
The distance and quality fields enable to control the quality of the spline surface brake down (triangulation) depending on the distance from the camera to the center of the object bounding box. The distance field specifies a set of distances to object. Each distance[i] value is correspond to the quality[i+1] value. The quality[0] value specifies the triangulation quality at distance=0. Thus, if the greatest index in the distance field is N, there shall be N+1 qualities in the quality field.
Let N denotes the greatest index in the distance field. The following equations define the current quality of the spline surface brake down:
D <= distance[0]:
Q = quality[0] + (quality[1] - quality[0]) * D / distance[0]
distance[i] < D < distance[i+1]:
Q = quality[i+1] + (quality[i+2] - quality[i+1]) * (D - distance[i]) / (distance[i+1] - distance[i])
distance[N-1] < D:
Q = quality[N],
where:
D - the distance from the camera to the center of the object bounding box.
Q - the current quality of the spline surface brake down, ranging from 0 for the worst quality to 1 for best surface.
Text3D
Incorporate 3D text into your VRML world and format it with any True Type font installed in your Windows system.
Node description
Text3D { exposedField MFString string [] exposedField SFNode fontStyle NULL exposedField MFFloat length [] # [0, inf) exposedField SFFloat maxExtent 0 # [0, inf) exposedField SFFloat depth 0.1 # [0, inf) exposedField SFFloat creaseAngle 0 # [0, inf) exposedField SFBool solid TRUE }
You can incorporate 3D text into your VRML world and format it with any True Type font installed in your Windows system. The Text3D node specifies a 3D text string object that is positioned with its middle vertical plane in the Z=0 plane of the local coordinate system, based on values defined in the fontStyle field. The Text3D nodes may contain multiple text strings using the UTF-8 encoding as specified by ISO 10646-1:1993. The text strings are stored in the order in which the text mode characters are to be produced as defined by the parameters in the FontStyle node. The fields of the Text3D node, with the exception of depth, creaseAngle and solid, are analogous to the ones for the Text node.
depth The depth field contains a SFFloat value that specifies the thickness of each text string in the local coordinate system. |
creaseAngle The creaseAngle field affects how default normals are generated. If the angle between the geometric normals of two adjacent faces is less than or equal to the specified value for the crease angle parameter, the edge between the two adjacent faces is smooth-shaded. Otherwise, the appearance of a rendered surface is calculated so that a lighting discontinuity is produced across the edge. |
solid The solid field determines whether one or both sides of each polygon should be displayed. If solid is FALSE, each polygon of 3D text will be visible regardless of the viewing direction. If solid is TRUE, this results in one-sided polygon lighting. |
Descriptions of the string, fontStyle, length, and maxExtent fields are provided in the VRML97 specification (see 6.47, Text).
Example
#VRML V2.0 utf8 NavigationInfo { type "EXAMINE" } DEF MainTransform Transform { children Shape { geometry Text3D { string ["@"] fontStyle FontStyle { justify ["MIDDLE", "MIDDLE"] family "Times" style "BOLD" size 4 } depth 0.5 } appearance Appearance { material Material { diffuseColor .28 .42 .6 specularColor .32 .4 .4 ambientIntensity .05 shininess .54 emissiveColor .14 .22 .31 } } } } DEF MainInterpolator OrientationInterpolator { key [ 0 0.5 1 ] keyValue [0 1 0 0 0 1 0 3.14 0 1 0 6.28] } DEF MainTimer TimeSensor { loop TRUE cycleInterval 5 } ROUTE MainTimer.fraction_changed TO MainInterpolator.set_fraction ROUTE MainInterpolator.value_changed TO MainTransform.rotation
TextureTransform3
The TextureTransform3 node defines a 3D transformation that is applied to texture coordinates used in environment mapping (3D transformation of the reflection vector).
EXTERNPROTO TextureTransform3 [ exposedField SFVec3f center 0 0 0 # (-inf,inf) exposedField SFRotation rotation 0 0 1 0 # [-1 1],(-inf,inf) exposedField SFVec3f scale 1 1 1 # (0,inf) exposedField SFRotation scaleOrientation 0 0 1 0 # [-1 1],(-inf,inf) exposedField SFVec3f translation 0 0 0 # (-inf,inf) ] [ "urn:inet:parallelgraphics.com:cortona:TextureTransform3" "http://www.cortona3d.com/source/extensions.wrl #TextureTransform3" ]
The fields of the TextureTransform3 node are analogous to the corresponding fields of the Transforms VRML node.
The TextureTransform3 node can be used as a value of the textureTransforms field of the AdvancedAppearance node. The texture, to which the transformation applies, should be specified in the textures field of the AdvancedAppearance node by the CubeEnvironment or SphereEnvironment nodes.
TransformSensor
EXTERNPROTO TransformSensor [ exposedField SFBool enabled #TRUE exposedField SFBool includeViewer #FALSE eventOut SFVec3f translation_changed eventOut SFRotation rotation_changed eventOut SFVec3f center_changed eventOut SFVec3f scale_changed eventOut SFRotation scaleOrientation_changed eventOut SFBool transform_changed ] [ "urn:inet:parallelgraphics.com:cortona:TransformSensor" "http://www.cortona3d.com/source/extensions.wrl#TransformSensor" ]
The TransformSensor generates events containing any transformations of the descendant geometry in the global coordinate system.
The includeViewer field specifies if viewer position is used in TransformSensor fields calculations or not.
The translation_changed event is generated if the translation is changed.
The rotation_changed event is generated if the rotation is changed.
The center_changed event is generated if the center of transform is changed.
The scale_changed event is generated if the scale is changed.
The scaleOrientation_changed event is generated if the scaleOrientation is changed.
The transform_changed event is generated if the transform is changed.
ViewportSensor
ViewportSensor node returns size of 3D window in pixels.
EXTERNPROTO ViewportSensor [ eventOut SFVec2f size_changed ] [ "urn:inet:parallelgraphics.com:cortona:ViewportSensor" "http://www.cortona3d.com/source/extensions.wrl#ViewportSensor" ]
The size_changed event is generated if the size of 3D window is changed.
ZGroup
The ZGroup node enables/disables writing children geometry in Z-buffer and checking Z-buffer during its output.
EXTERNPROTO ZGroup [ eventIn MFNode addChildren eventIn MFNode removeChildren exposedField MFNode children [] field SFVec3f bboxCenter 0 0 0 # (-inf inf) field SFVec3f bboxSize -1 -1 -1 # (0, inf) or -1,-1,-1 exposedField SFBool write TRUE exposedField SFBool check TRUE exposedField SFBool writePixelBuffer TRUE ] [ "urn:inet:parallelgraphics.com:cortona:ZGroup" "http://www.cortona3d.com/source/extensions.wrl#ZGroup" ]
The fields of the ZGroup node, with the exception of the check, and write fields, are analogous to the corresponding fields of the Group VRML node.
Fields and events
check Specifies whether Z-buffer is checked during rendering of geometry specified in the children field. |
write Specifies whether the children geometry should be written to Z-buffer. |
writePixelBuffer Specifies whether the children geometry should be written to pixel-buffer. The default value of writePixelBuffer is TRUE. |