[PyOpenGL-Users] glVertexArrayd slows performance

[Douglas T. <dt...@sk...>]

Hi,

I've been trying to improve a dot drawing routine
and I tried the vertex array method but it slows
performance by a factor of 2. My testing machine
runs Mac OSX 10.3.9 and has PyOpenGL version 2.0.2.01 .
I tried allocating the xyData array 2 ways and both have
the same performance

1) xyData = RandomArray.uniform(0.0,1.0, (NUM_POINTS,2))

2)  xyData = Numeric.zeros( (NUM_POINTS,2), 'd')

and the code looks as

        if use_vertex_array == False:
            glColor4f(1.0, 0.0, 0.0,1.0);
            glBegin(GL_POINTS);
            for i in range(NUM_POINTS):
               glVertex3f(xstart[i],ystart[i],zstart[i]);
            glEnd()
        else:
        # Pass a pointer to the start of the point-coordinate array:
            glColor4f(0.0, 1.0, 0.0,1.0);
            xyData[:,0] = xstart
            xyData[:,1] = ystart
            glVertexPointerd(xyData);
            glEnableClientState(GL_VERTEX_ARRAY);
            glDrawArrays(GL_POINTS, 0, len(xstart));
            glDisableClientState(GL_VERTEX_ARRAY);

By timing parts of the code it spends most of it's time in
            glVertexPointerd(xyData);
the call to glDrawArrays(GL_POINTS, 0, len(xstart)); is quite fast.
Am I doing something wrong here? Any help would be
greatly appreciated. Thanks,

Doug Taylor