Re: [PyOpenGL-Users] VBO question

[Henry G. <he...@ca...>]

On Mon, 2011-06-20 at 12:20 -0700, Jason Hayes wrote:
> # send vertices over to the GPU self.vbo_name = glGenBuffersARB( 1 )
> glBindBufferARB( GL_ARRAY_BUFFER_ARB, self.vbo_name )
> glBufferDataARB( GL_ARRAY_BUFFER_ARB, vertices, GL_STATIC_DRAW_ARB ) 

I'm not an expert, but don't you still need to copy the data to the
buffer. I'm not quite sure how you've managed with 3 arguments there
though. The docs all suggest you need 4.

After that I think you need to do something like (modified from my pbo
code, which is all in terms of numpy arrays, which are well laid out in
memory):

        # Map the buffer object to a pointer
        vbo_pointer = ctypes.cast(\
                GL.glMapBuffer(GL.GL_ARRAY_BUFFER, GL.GL_WRITE_ONLY),
                ctypes.POINTER(ctypes.c_ubyte))
        
        # Turn that pointer into a numpy array that spans
        # the whole block.(buffer size is the size of your buffer)
        vbo_array = numpy.ctypeslib.as_array(vbo_pointer,
                    (buffer_size,))
        
        vbo_array[0:data_size_to_copy] = \
                    data.view(dtype='uint8').ravel()

        # Unmap the buffer.
        GL.glUnmapBuffer(GL.GL_ARRAY_BUFFER) 

Hope that helps.

cheers,

Henry