Sorry, I should have mentioned that the positions
are changing every frame. Thanks,

Doug


-------- Original Message --------
Subject: [PyOpenGL-Users] glVertexArrayd slows performance
Date: Sat, 04 Feb 2006 16:46:50 -0800
From: Douglas Taylor <dtaylor@ski.org>
To: pyopengl-users@lists.sourceforge.net


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





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