Hi Bryan,
As a general guide never use array indices with osg::Geometry as it
forces the OSG down onto OpenGL slow paths - OpenGL itself simply
doesn't support deferences on indices separately for each vertex
arrays.
The way to do indexing is use DrawElementsUShort() instead of
DrawArrays. This may require repeating some values but it far more
efficient for OpenGL to handle.
I don't know why you code segment gives examples of using
TemplateIndexArray, this is just confusing alround, the typesefs in
include/osg/Array for FloatArray, Vec2Array etc are much much more
readable.
On 6/27/07, Wasileski, Bryan J. <[EMAIL PROTECTED]> wrote:
Hi All,
The question below is being forwarded from "Larry"...
I was wondering if someone could explain how setVertexAttribIndices
works. In my application, I have an array of vertices that I set for my
geometry. I then build my triangle primitives using those vertices (when
I build my triangles, some vertices are used more than once). If I want
to assign an attribute variable to be accessed by my shaders, do I have
to assign it twice for the vertices that are repeated or just once? If
not, is the indexArray that I am passing into setVertexAttribIndices
array just a 1:1 mapping with the indices of my vertex array? Currently,
when I have my attribute array the same size as my vertices, I get a
segmentation fault. Here is the code I am using:
TemplateIndexArray <unsigned int, Array::UIntArrayType, 1,
GL_UNSIGNED_INT> *index;
index = new TemplateIndexArray<unsigned int, Array::UIntArrayType, 1,
GL_UNSIGNED_INT>;
for (int i = 0; i < itsVertices->size(); i++)
{
index->push_back(i); // vertex 0 assigned color array element
}
TemplateArray <GLfloat, Array::FloatArrayType, 1, GL_FLOAT>*
thePatchAttributes = new TemplateArray <GLfloat, Array::FloatArrayType,
1, GL_FLOAT>;
for (int i = 0; i < itsVertices->size(); i++)
{
thePatchAttributes->push_back(info[0] + info[1]);
}
itsGeometry->setVertexAttribArray (6, thePatchAttributes);
itsGeometry->setVertexAttribIndices(6, index);
itsGeometry->setVertexAttribBinding (6, osg::Geometry::BIND_PER_VERTEX);
Thanks.
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