[vtkusers] What's the best/correct way to pass vtkIdType to a glBufferData call?

[Justin Rosen]

I'm trying to write my own vtkVBO mapper to pass polyData to a vertex
buffer object but I'm not sure how to setup the indices array

// Indices vbo
vtkgl::GenBuffers(1, &VBOIndicesId);
vtkgl::BindBuffer(vtkgl::ELEMENT_ARRAY_BUFFER, VBOIndicesId);

I found some code in vtkOpenGLPainterDeviceAdapter.cxx

// This seems really inefficient for handling vtkIdType when they
// are 64 bit, but OpenGL does not handle 64 bit indices.  What
// else can I do?

vtkIdType *oldarray = static_cast<vtkIdType *>(indices);
GLuint *newarray = new GLuint[count];
std::copy(oldarray, oldarray + count, newarray);
glDrawElements(VTK2OpenGLPrimitive[mode], static_cast<GLsizei>(count),
GL_UNSIGNED_INT,
newarray);

But, this doesn't seem to help as newarray still contains the tuple data,
ie (1, id) resulting in twice the data

For now, I don't really need the indice values stored in each cell as I'm
displaying everything and the range 0-count as an array is okay

vtkPolyData *input= this->GetInput();
vtkPoints *points = input->GetPoints();
vtkCellArray *verts = input->GetVerts();
vtkIdType *pIds = verts->GetPointer();
unsigned int numPoints = points->GetNumberOfPoints();

// For now, display every indice
unsigned int *indices = new unsigned int[numPoints];
for (size_t i=0; i < numPoints; i++)
    indices[i] = i;

vtkgl::BufferData(vtkgl::ELEMENT_ARRAY_BUFFER, numPoints * sizeof(unsigned
int), indices, vtkgl::DYNAMIC_DRAW);


Thanks!
Justin
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