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SoQuadMesh.3coin2

NAME

SoQuadMesh -

The SoQuadMesh class is used to render and optimize a quadrilateral mesh.

This node uses the coordinates in order, either from the state or from the SoQuadMesh::vertexProperty node, to construct a quadrilateral mesh.

SYNOPSIS

#include <Inventor/nodes/SoQuadMesh.h>

Inherits SoNonIndexedShape.

Public Member Functions

SoQuadMesh (void)

virtual void GLRender (SoGLRenderAction *action)

virtual void getPrimitiveCount (SoGetPrimitiveCountAction *action)

virtual SbBool generateDefaultNormals (SoState *state, SoNormalBundle *nb)

Static Public Member Functions

static void initClass (void)

Public Attributes

SoSFInt32 verticesPerColumn

SoSFInt32 verticesPerRow

Protected Member Functions

virtual ~SoQuadMesh ()

virtual void generatePrimitives (SoAction *action)

virtual void computeBBox (SoAction *action, SbBox3f &box, SbVec3f &center)

virtual SbBool generateDefaultNormals (SoState *, SoNormalCache *)

Detailed Description

The SoQuadMesh class is used to render and optimize a quadrilateral mesh.

This node uses the coordinates in order, either from the state or from the SoQuadMesh::vertexProperty node, to construct a quadrilateral mesh.

The quads are generated in row major order, using the two fields SoQuadMesh::verticesPerColumn and SoQuadMesh::verticesPerRow to specify the mesh. E.g. if SoQuadMesh::verticesPerColumn is 3 and SoQuadMesh::verticesPerRow is 2, two quads will be generated with the first one using (in order) coordinates 0, 1, 3 and 2, the second one using coordinates 2, 3, 5 and 4 (you get three rows of vertices; the first row uses vertices 0 and 1, the second row 2 and 3, and the third row 4 and 5).

Here's a quick and simple usage example code snippet:

   // Vertices for the Quad mesh.
   static float vertices[25][3] = {
     // Row 1
     {-11, 0, 1}, {0, 11, 1}, {11, 0, 1}, {0, -11, 1}, {-11, 0, 1},
     // Row 2
     {-9, 0, 1}, {0, 9, 1}, {9, 0, 1}, {0, -9, 1}, {-9, 0, 1},
     // Row 3
     {-9, 0, -1}, {0, 9, -1}, {9, 0, -1}, {0, -9, -1}, {-9, 0, -1},
     // Row 4
     {-11, 0, -1}, {0, 11, -1}, {11, 0, -1}, {0, -11, -1}, {-11, 0, -1},
     // Row 5
     {-11, 0, 1}, {0, 11, 1}, {11, 0, 1}, {0, -11, 1}, {-11, 0, 1}
   };
 
   // This function generate an object by using the SoQuadMesh node
   // Return:
   //  SoSeparator *
   static SoSeparator *
   quadMesh(void)
   {
     SoSeparator * qm = new SoSeparator;
 
     // Define coordinates
     SoCoordinate3 * coords = new SoCoordinate3;
     coords->point.setValues(0, 30, vertices);
     qm->addChild(coords);
 
     // QuadMesh
     SoQuadMesh * mesh = new SoQuadMesh;
     mesh->verticesPerRow = 5;
     mesh->verticesPerColumn = 5;
     qm->addChild(mesh);
 
     return qm;
   }
 

The quadmesh geometry resulting from this code looks like this:

  

Here is another example, this time making a 2x2 grid, with a texture:

 
   #Inventor V2.1 ascii
   
   Separator {
     Complexity { textureQuality 0.01 }
     Texture2 { 
       image 2 2 4 0xff0000ff 0x00ff00ff 0xffff00ff 0xff00ffff
     }
     Coordinate3 { 
       point [
         0 2 0,
         1 2 0,
         2 2 0,
         0 1 0,
         1 1 0,
         2 1 0,
         0 0 0,
         1 0 0,
         2 0 0
       ]
     }
     QuadMesh {
       verticesPerRow 3
       verticesPerColumn 3
     }
   }
   .fi
 
 
 For SoQuadMesh, normals and materials can be bound PER_PART (per row), PER_FACE, PER_VERTEX and OVERALL. The default material binding is OVERALL. The default normal binding is PER_VERTEX.
 
 A note about SoQuadMesh shading: the quads in the mesh are just passed on to OpenGL's GL_QUAD primitive rendering. Under certain circumstances, this can lead to artifacts in how your meshes are shaded. This is an inherent problem with drawing quads in meshes.
 
 There is a work-around solution for the above mentioned problem that can be applied with Coin: by setting the global environment variable COIN_QUADMESH_PRECISE_LIGHTING to '1', the quads will be broken up in triangles before rendered, and shading will likely look much better. Be aware that this technique causes rendering of the SoQuadMesh to slow down by an approximate factor of 6.
 
 The 'precise lighting' technique is currently limited to work only when SoQuadMesh rendering is parameterized with 3D coordinates, a materialbinding that is not per vertex, and if texture mapping is done is must be without using any of the SoTextureCoordinateFunction subclass nodes.
 
 FILE FORMAT/DEFAULTS: 
 
     QuadMesh {
         vertexProperty NULL
         startIndex 0
         verticesPerColumn 1
         verticesPerRow 1
     }
 
 

See also:

SoTriangleStripSet SoIndexedTriangleStripSet

Constructor & Destructor Documentation

SoQuadMesh::SoQuadMesh (void)Constructor.

References verticesPerColumn, and verticesPerRow.

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

Member Function Documentation

static void sogl_qmesh_m3_n3_t1_pl void SoQuadMesh::initClass (void) [static]Sets up initialization for data common to all instances of this class, like submitting necessary information to the Coin type system.

Reimplemented from SoNonIndexedShape.

void SoQuadMesh::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.

References SoVertexShape::generateAndReadLockNormalCache(), SoAction::getState(), SoVertexShape::getVertexData(), SoNode::GLRender(), SoState::pop(), SoDebugError::postWarning(), SoState::push(), SoVertexShape::readUnlockNormalCache(), SoVertexShape::shouldGLRender(), SoNonIndexedShape::startIndex, SoVertexShape::vertexProperty, verticesPerColumn, and verticesPerRow.

void SoQuadMesh::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.

References SoGetPrimitiveCountAction::addNumTriangles(), SoShape::shouldPrimitiveCount(), verticesPerColumn, and verticesPerRow.

SbBool SoQuadMesh::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 SoQuadMesh::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.

References SoShape::beginShape(), SoNode::doAction(), SoShape::endShape(), SoVertexShape::generateAndReadLockNormalCache(), SoAction::getState(), SoVertexShape::getVertexData(), SoFaceDetail::incFaceIndex(), SoFaceDetail::incPartIndex(), SoState::pop(), SoState::push(), SoVertexShape::readUnlockNormalCache(), SoPointDetail::setCoordinateIndex(), SoPrimitiveVertex::setDetail(), SoFaceDetail::setFaceIndex(), SoPrimitiveVertex::setMaterialIndex(), SoPointDetail::setMaterialIndex(), SoPrimitiveVertex::setNormal(), SoPointDetail::setNormalIndex(), SoPrimitiveVertex::setPoint(), SoPointDetail::setTextureCoordIndex(), SoPrimitiveVertex::setTextureCoords(), SoShape::shapeVertex(), SoNonIndexedShape::startIndex, SoVertexShape::vertexProperty, verticesPerColumn, and verticesPerRow.

void SoQuadMesh::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.

References SoNonIndexedShape::computeCoordBBox(), verticesPerColumn, and verticesPerRow.

SbBool SoQuadMesh::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.

References SoNonIndexedShape::startIndex, verticesPerColumn, and verticesPerRow.

Member Data Documentation

SoSFInt32 SoQuadMesh::verticesPerColumnSpecifies to number of vertices in each column.

Referenced by computeBBox(), generateDefaultNormals(), generatePrimitives(), getPrimitiveCount(), GLRender(), and SoQuadMesh().

SoSFInt32 SoQuadMesh::verticesPerRowSpecifies the number of vertices in each row.

Referenced by computeBBox(), generateDefaultNormals(), generatePrimitives(), getPrimitiveCount(), GLRender(), and SoQuadMesh().

Author

Generated automatically by Doxygen for Coin from the source code.