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
¢er)
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.
SoQuadMesh::~SoQuadMesh () [protected, virtual] Destructor.
Member Function Documentation
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.
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.
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.
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.
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.
Member Data Documentation
SoSFInt32 SoQuadMesh::verticesPerColumn Specifies to number of vertices in
each column.
SoSFInt32 SoQuadMesh::verticesPerRow Specifies the number of vertices in
each row.
Author
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