Re: [PyOpenGL-Users] Using Vertex and index buffer objects in glDrawElements(...)

[Mike C. F. <mcf...@vr...>]

Richard Guercke wrote:
> Hi,
> I’d like to know what I am doing wrong.
> I want to transfer an array with vertices and another one with index data into buffers on the graphics card and use them in a drawElements(..) call.
> As a beginner with OpenGL (coming from Java3d), I am looking for an example that works with PyOpenGL. The C code that I have found on the Internet does not really help in this context because the problem is possibly my lack of understanding the PyOpenGL wrapping.
> Here is the code I tried:
>   
There are a few convenience mechanisms in PyOpenGL, so your VBOs can be
defined like so:

    from OpenGL.arrays import vbo
    verts = vbo.VBO( array([[ 0,0,0 ], [ 9,0,0 ], [ 0,9,0 ], [ 0,0,9 ]],
dtype=float32) )
    idxs = vbo.VBO( array([ 0,1, 0,2, 0,3],dtype=ubyte),
target=GL_ELEMENT_ARRAY_BUFFER )
    verts.bind()
    glEnableClientState(GL_VERTEX_ARRAY)
    glVertexPointer(..., verts )
    idxs.bind()
    glDrawElements( ..., idxs )

the 0's in your calls are getting converted to 1-element arrays of
ints.  A ctypes.c_void_p( 0 ) should work fine, if you don't want to use
a vbo object.

HTH,
Mike

-- 
________________________________________________
  Mike C. Fletcher
  Designer, VR Plumber, Coder
  http://www.vrplumber.com
  http://blog.vrplumber.com