SoIndexedFaceSet -

#include <Inventor/nodes/SoIndexedFaceSet.h>

Inherits SoIndexedShape.

The SoIndexedFaceSet class is used to handle generic indexed facesets.

Faces are specified using the coordIndex field. Each face must be terminated by a negative (-1) index. Coordinates, normals, materials and texture coordinates from the current state (or from the vertexProperty node if set), can be indexed to create triangles, quads or polygons.

Here's a usage example of just about the simplest possible use of this node, to show a single polygon face:

  #Inventor V2.1 ascii
  
  Separator {
     Coordinate3 {
        point [ 0 0 0, 1 0 0, 1 1 0 ]
     }
     IndexedFaceSet {
        coordIndex [ 0, 1, 2, -1 ]
     }
  }
  .fi


Binding PER_VERTEX_INDEXED, PER_VERTEX, PER_FACE_INDEXED, PER_FACE or OVERALL can be set for material, and normals. The default material binding is OVERALL. The default normal binding is PER_VERTEX_INDEXED. When PER_VERTEX_INDEXED binding is used and the corresponding materialIndex, normalIndex, texCoordIndex field is empty, the coordIndex field will be used to index material, normal or texture coordinate. If you do specify indices for material, normals or texture coordinates for PER_VERTEX_INDEXED binding, make sure your index array matches the coordIndex array: there should be a -1 wherever there is a -1 in the coordIndex field. This is done to make this node more easily readable for humans.

A fairly common request when rendering facesets is how to display a set of faces with different colors on the backside versus the frontside. There is not direct support for this in the API, but it can easily be implemented by duplicating all faces in both the SoShapeHints::COUNTERCLOCKWISE and the SoShapeHints::CLOCKWISE order. Here is a simple usage example, showing the technique for a single polygon, using two SoFaceSet nodes for rendering the same polygon from both sides:


  #Inventor V2.1 ascii
  
  Separator {
     Coordinate3 { point [ 0 0 0, 1 0 0, 1 1 0 ] }
  
     Separator {
        Material { diffuseColor [ 1 1 0 ] }
        ShapeHints {
           vertexOrdering COUNTERCLOCKWISE
           shapeType SOLID
        }
        FaceSet { numVertices [ 3 ] }
     }
  
     Separator {
        Material { diffuseColor [ 1 0 0 ] }
        ShapeHints {
           vertexOrdering CLOCKWISE
           shapeType SOLID
        }
        FaceSet { numVertices [ 3 ] }
     }
  }
  .fi


The same effect can also be done in the following manner, using an SoIndexedFaceSet to explicitly render the polygon coordinates in both directions (clockwise and counterclockwise):


  #Inventor V2.1 ascii
  
  Separator {
     Coordinate3 { point [ 0 0 0, 1 0 0, 1 1 0 ] }
  
     Material { diffuseColor [ 1 0 0, 1 1 0 ] }
     MaterialBinding { value PER_FACE_INDEXED }
  
     ShapeHints {
        vertexOrdering COUNTERCLOCKWISE
        shapeType SOLID
     }
  
     IndexedFaceSet {
        coordIndex [ 0, 1, 2, -1, 2, 1, 0, -1 ]
        materialIndex [ 0, 1 ]
     }
  }
  .fi


Another rather rare issue that might be interesting to know about is that to render polygons with concave borders, you should set up an SoShapeHints node with SoShapeHints::faceType set to SoShapeHints::UNKNOWN_FACE_TYPE in the scene graph before the SoIndexedFaceSet (or SoFaceSet) node. This needs to be done to force the rendering code to tessellate the polygons properly to triangles before sending it off to OpenGL. Without it, the polygons will be sent as-is to OpenGL, and the OpenGL implementation's tessellator is often not able to tessellate properly. Here is an example which usually fails without the SoShapeHints node (try commenting it out, and see what happens):


  #Inventor V2.1 ascii
  
  ShapeHints { faceType UNKNOWN_FACE_TYPE }
  
  Coordinate3
  {
          point [ 2 0 0,
                  1 0 0,
                  1 1 0,
                  0 1 0,
                  0 2 0,
                  1 2 0,
                  2 2 0,
                  2 1 0 ]
  }
  
  FaceSet {}
  .fi


FILE FORMAT/DEFAULTS: 

    IndexedFaceSet {
        vertexProperty NULL
        coordIndex 0
        materialIndex -1
        normalIndex -1
        textureCoordIndex -1
    }



See also:
SoFaceSet, SoIndexedTriangleStripSet 

Public Member Functions

Static Public Member Functions

Protected Member Functions

Static Protected Member Functions

SoIndexedFaceSet::SoIndexedFaceSet (void)

SoIndexedFaceSet::~SoIndexedFaceSet () [protected, virtual]

SoType SoIndexedFaceSet::getClassTypeId (void) [static]

SoType SoIndexedFaceSet::getTypeId (void) const [virtual]

  void foo(SoNode * node)
  {
    if (node->getTypeId() == SoFile::getClassTypeId()) {
      SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
    }
    else if (node->getTypeId().isOfType(SoGroup::getClassTypeId())) {
      SoGroup * group = (SoGroup *)node;  // safe downward cast, knows the type
    }
  }

const SoFieldData ** SoIndexedFaceSet::getFieldDataPtr (void) [static, protected]

const SoFieldData * SoIndexedFaceSet::getFieldData (void) const [protected, virtual]

void SoIndexedFaceSet::initClass (void) [static]

void SoIndexedFaceSet::GLRender (SoGLRenderAction * action) [virtual]

void SoIndexedFaceSet::getPrimitiveCount (SoGetPrimitiveCountAction * action) [virtual]

SbBool SoIndexedFaceSet::generateDefaultNormals (SoState * state, SoNormalBundle * bundle) [virtual]

SbBool SoIndexedFaceSet::generateDefaultNormals (SoState * state, SoNormalCache * cache) [virtual]

void SoIndexedFaceSet::generatePrimitives (SoAction * action) [protected, virtual]

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