SoFaceSet Class Reference
[Shapes]
Polygonal face shape node. More...
#include <Inventor/nodes/SoFaceSet.h>
Public Member Functions | |
| virtual SoType | getTypeId () const |
| SoFaceSet () | |
Static Public Member Functions | |
| static SoType | getClassTypeId () |
Public Attributes | |
| SoMFInt32 | numVertices |
Detailed Description
Polygonal face shape node.
This node represents a 3D shape formed by constructing faces (polygons) from vertices located at the coordinates specified in the vertexProperty field (from SoVertexShape), or the current inherited state. For optimal performance, the vertexProperty field is recommended.
Coordinates are used in order, starting with startIndex (zero by default).
If the first value in the numVertices field is -1 (the default), then all the coordinates (starting with startIndex) are rendered as a single face.
Otherwise each face uses the number of vertices specified by a value in the numVertices field. For example, an SoFaceSet with a numVertices of [3,4,4] would use the first three coordinates for the first face, the next four coordinates for the second face, and the next four coordinates for the third face. Thus the number of values in the numVertices field indicates the number of faces in the set.
SoFaceSet should only be used to render faces with 3 or more vertices. Otherwise the result is undefined. For example, do not set values in the numVertices field to 0, 1 or 2. To render lines or points, use SoLineSet or SoPointSet respectively.
SoFaceSet is a general purpose polygon rendering node. It can render triangles, quadrilaterals, and other types of polygons or any combination thereof. However:
- For best performance, arrange the faces with all triangles first, then all quadrilaterals, then general polygons.
- If the shape has only triangles, use SoTriangleSet instead (simpler and possibly faster).
SoFaceSet supports both convex and non-convex polygons (unlike OpenGL). However polygons are assumed to be convex by default. Rendering non-convex polygons in this mode may produce incorrect results. Enable non-convex polygons using the faceType field of an SoShapeHints node. In this mode SoFaceSet will automatically convert non-convex polygons, if necessary, to faces that the hardware can handle.
SoFaceSet can also directly handle complex polygons with "holes" (interior boundaries). See the following paragraphs.
If SoShapeHints is not used, or if the SoShapeHints::windingType field is equal to NO_WINDING_TYPE, SoFaceSet defines a set of faces. It uses the coordinates in order, starting with startIndex. Each face has a number of vertices specified by a value in the numVertices field. For example, an SoFaceSet with numVertices of [3,4,4] would use coordinates 1, 2, and 3 for the first face, coordinates 4, 5, 6, and 7 for the second face, and coordinates 8, 9, 10, and 11 for the third. The number of values in the numVertices field indicates the number of faces in the set. The default value (-1) means to use all the coordinates to define a single face.
If SoShapeHints is used with a SoShapeHints::windingType field is different from NO_WINDING_TYPE, SoFaceSet defines a complex (multi-contour) face. It uses the coordinates in order, starting with the first one. Each contour has a number of vertices specified by a value in the numVertices field. For example, an SoFaceSet with numVertices of [3,4,4] would use coordinates 1, 2, and 3 for the first contour, coordinates 4, 5, 6, and 7 for the second contour, and coordinates 8, 9, 10, and 11 for the third. The number of values in the numVertices field indicates the number of contours in the complex face.
The coordinates of the face set are transformed by the current cumulative transformation. The faces are drawn with the current light model and drawing style (SoDrawStyle). Diffuse color and opacity may be specified using the orderedRGBA field of SoVertexProperty. Diffuse color, transparency and other color parameters used in the lighting equation may be specified using SoMaterial.
Treatment of the current material and normal binding is as follows: The PER_PART and PER_FACE bindings specify a material or normal for each face. The _INDEXED bindings are equivalent to their non-indexed counterparts. The default material binding is OVERALL. The default normal binding is PER_VERTEX.
If any normals (or materials) are specified, Open Inventor assumes you provide the correct number of them, as indicated by the binding. You will see unexpected results if you specify fewer normals (or materials) than the shape requires.
Lighting is enabled by default (see SoLightModel). If lighting is enabled, by default only the "front face" of polygons are lit (the back face will be black). Which side is the front face is determined by the normal vector, if specified, else by the ordering of the vertices and the vertexOrdering field of SoShapeHints. You can also enable "two sided lighting" using SoShapeHints.
If lighting is enabled and no normals were specified, they will be computed automatically. The normal generator computes "facet" or "smooth" (or a combination) normal vectors depending on the creaseAngle field of SoShapeHints.
Textures may be applied using (for example) SoTexture2. Texture coordinates may be supplied using SoVertexProperty or SoTextureCoordinate2. If a texture is applied and no texture coordinates were specified, they will be computed automatically. By default the computed coordinates map the texture to the axis-aligned bounding box of the shape, with the texture S axis corresponding to the longest axis of the box.
Warning: A face set may not render or pick correctly if any of its polygons are self-intersecting or non-planar.
Limitations:
- Due to limitations of the OpenGL VBO (vertex buffer object) rendering model, it is not possible to use VBO rendering (and performance may be lower) if either the normal binding or the material binding is set to either PER_PART(_INDEXED) or PER_FACE(_INDEXED).
FILE FORMAT/DEFAULT
- FaceSet {
| vertexProperty | NULL |
| startIndex | 0 |
| numVertices | -1 |
ACTION BEHAVIOR
- SoGLRenderAction
Draws faces based on the current coordinates, normals, materials, drawing style, and so on.
SoRayPickAction
Picks faces based on the current coordinates and transformation. Details about the intersection are returned in an SoFaceDetail.
SoGetBoundingBoxAction
Computes the bounding box that encloses all vertices of the face set with the current transformation applied to them. Sets the center to the average of the coordinates of all vertices.
SoCallbackAction
If any triangle callbacks are registered with the action, they will be invoked for each successive triangle generated from each face in the set.
SEE ALSO
SoCoordinate3, SoDrawStyle, SoFaceDetail, SoFullSceneAntialiasing, SoIndexedFaceSet, SoShapeHints, SoTriangleSet, SoVertexProperty
- See related examples:
Constructor & Destructor Documentation
| SoFaceSet::SoFaceSet | ( | ) |
Creates a face set node with default settings.
Member Function Documentation
| static SoType SoFaceSet::getClassTypeId | ( | ) | [static] |
Returns the type identifier for this class.
Reimplemented from SoNonIndexedShape.
Reimplemented in SoVolumeFaceSet.
| virtual SoType SoFaceSet::getTypeId | ( | ) | const [virtual] |
Returns the type identifier for this specific instance.
Reimplemented from SoNonIndexedShape.
Reimplemented in SoVolumeFaceSet.
Member Data Documentation
Number of vertices per face or per contour.
The documentation for this class was generated from the following file:
- Inventor/nodes/SoFaceSet.h