SoTriangleStripSet(3)

NAME
SoTriangleStripSet - The SoTriangleStripSet class is used to render and control non-indexed triangle strips.

Triangle strips are specified using the numVertices field.

SYNOPSIS

#include <Inventor/nodes/SoTriangleStripSet.h>

Inherits SoNonIndexedShape.

  Public Member Functions
virtual SoType getTypeId (void) const
SoTriangleStripSet (void)
virtual void GLRender (SoGLRenderAction *action)
virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)
virtual SbBool generateDefaultNormals (SoState *state, SoNormalBundle *nb)

  Static Public Member Functions
static SoType getClassTypeId (void)
static void initClass (void)

  Public Attributes
SoMFInt32 numVertices

  Protected Member Functions
virtual const SoFieldData * getFieldData (void) const
virtual ~SoTriangleStripSet ()
virtual void generatePrimitives (SoAction *action)
virtual void computeBBox (SoAction *action, SbBox3f &box, SbVec3f &center)
virtual SbBool generateDefaultNormals (SoState *, SoNormalCache *)

  Static Protected Member Functions
static const SoFieldData ** getFieldDataPtr (void)

  Additional Inherited Members

Detailed Description

The SoTriangleStripSet class is used to render and control non-indexed triangle strips.

Triangle strips are specified using the numVertices field. Coordinates, normals, materials and texture coordinates are all fetched in order from the current state or from the vertexProperty node if set. (To render triangle strips from vertex indices, use the SoIndexedTriangleStripSet node.)

The numVertices field may be used for multiple strips, coordinates will be fetched with a monotonically increasing index from the coordinates on the traversal state stack (i.e. typically from the last SoCoordinate3 node encountered during traversal).

For example, if numVertices is set to [3, 4, 5, 3], this node would specify a triangle from coordinates 0, 1 and 2, a triangle strip from coordinates 3, 4, 5 and 6, a triangle strip from coordinates 7, 8, 9, 10 and 11 and finally a triangle from coordinates 12, 13, 14.

Or to put it another way: in a tristrip there will always be two vertices more than there are triangles. Realize that you are handling data on the vertex level (not polygon-level), and that the triangles are laid out like this, given 5 vertices:

1-----3-----5
    /    /
   /    /
   2-----4.fi

The above figure in scene graph file format:

#Inventor V2.1 ascii
Separator {
  Coordinate3 {
    point [ -2 1 0, -1 -1 0, 0 1 0, 1 -1 0, 2 1 0 ]
  }
  TriangleStripSet {
    numVertices [ 5 ]
  }
}

The scene graph above in a viewer:

Strips are converted into triangles the way OpenGL does it, of course, so for the dirty details, check out the documentation of OpenGL's GL_TRIANGLE_STRIP primitive rendering type.

Binding PER_PART (per strip), PER_VERTEX, PER_FACE or OVERALL can be set for material, and normals. The default material binding is OVERALL. The default normal binding is PER_VERTEX.

FILE FORMAT/DEFAULTS:

TriangleStripSet {
    vertexProperty NULL
    startIndex 0
    numVertices -1
}

See also:
    SoIndexedTriangleStripSet

Constructor & Destructor Documentation

  SoTriangleStripSet::SoTriangleStripSet (void)
Constructor.

  SoTriangleStripSet::~SoTriangleStripSet () [protected], [virtual]
Destructor.

Member Function Documentation

  SoType SoTriangleStripSet::getTypeId (void) const [virtual]
Returns the type identification of an object derived from a class inheriting SoBase. This is used for run-time type checking and 'downward' casting.

Usage example:

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

For application programmers wanting to extend the library with new nodes, engines, nodekits, draggers or others: this method needs to be overridden in all subclasses. This is typically done as part of setting up the full type system for extension classes, which is usually accomplished by using the pre-defined macros available through for instance Inventor/nodes/SoSubNode.h (SO_NODE_INIT_CLASS and SO_NODE_CONSTRUCTOR for node classes), Inventor/engines/SoSubEngine.h (for engine classes) and so on.

For more information on writing Coin extensions, see the class documentation of the toplevel superclasses for the various class groups.

Reimplemented from SoNonIndexedShape.

  const SoFieldData * SoTriangleStripSet::getFieldData (void) const [protected], [virtual]
Returns a pointer to the class-wide field data storage object for this instance. If no fields are present, returns NULL.

Reimplemented from SoNonIndexedShape.

  void SoTriangleStripSet::GLRender (SoGLRenderAction * action) [virtual]
Action method for the SoGLRenderAction.

This is called during rendering traversals. Nodes influencing the rendering state in any way or who wants to throw geometry primitives at OpenGL overrides this method.

Reimplemented from SoShape.

  void SoTriangleStripSet::getPrimitiveCount (SoGetPrimitiveCountAction * action) [virtual]
Action method for the SoGetPrimitiveCountAction.

Calculates the number of triangle, line segment and point primitives for the node and adds these to the counters of the action.

Nodes influencing how geometry nodes calculates their primitive count also overrides this method to change the relevant state variables.

Reimplemented from SoShape.

  SbBool SoTriangleStripSet::generateDefaultNormals (SoState * state, SoNormalBundle * bundle) [virtual]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Subclasses should override this method to generate default normals using the SoNormalBundle class. TRUE should be returned if normals were generated, FALSE otherwise.

Default method returns FALSE.

This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

Reimplemented from SoVertexShape.

  void SoTriangleStripSet::generatePrimitives (SoAction * action) [protected], [virtual]
The method implements action behavior for shape nodes for SoCallbackAction. It is invoked from SoShape::callback(). (Subclasses should not override SoNode::callback().)

The subclass implementations uses the convenience methods SoShape::beginShape(), SoShape::shapeVertex(), and SoShape::endShape(), with SoDetail instances, to pass the primitives making up the shape back to the caller.

Implements SoShape.

  void SoTriangleStripSet::computeBBox (SoAction * action, SbBox3f & box, SbVec3f & center) [protected], [virtual]
Implemented by SoShape subclasses to let the SoShape superclass know the exact size and weighted center point of the shape's bounding box.

The bounding box and center point should be calculated and returned in the local coordinate system.

The method implements action behavior for shape nodes for SoGetBoundingBoxAction. It is invoked from SoShape::getBoundingBox(). (Subclasses should not override SoNode::getBoundingBox().)

The box parameter sent in is guaranteed to be an empty box, while center is undefined upon function entry.

Implements SoShape.

  SbBool SoTriangleStripSet::generateDefaultNormals (SoState * state, SoNormalCache * cache) [protected], [virtual]
This API member is considered internal to the library, as it is not likely to be of interest to the application programmer.

Subclasses should override this method to generate default normals using the SoNormalCache class. This is more effective than using SoNormalGenerator. Return TRUE if normals were generated, FALSE otherwise.

Default method just returns FALSE.

This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

Reimplemented from SoVertexShape.

Member Data Documentation

  SoMFInt32 SoTriangleStripSet::numVertices
Specifies the number of vertices in each triangle strip. The vertices are fetched from the current coordinate node, or from the vertexProperty field if present.

Author

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