[PyOpenGL-Users] constructing a VBO containing mixture of floats, ubytes, etc

[Jonathan H. <ta...@ta...>]

Hey,

I am using vbo.VBO, constructed using a single array of (position, 
color, normal) - all floats. This looks like:

         self.vbo = vbo.VBO( array( list(
                     list(chain(v, c, n))
                     for v, c, n in zip(verts, colors, normals)
                 ),
                 'f'
             ),
             usage='GL_STATIC_DRAW'
         )

where verts, colors, normals are each generator expressions containing 
named tuples of (x, y, z) or (r, g, b), etc.

My problem is that I want to try out converting the colors to unsigned 
bytes instead of floats. When I was using vertex arrays instead of VBOs, 
using unsigned bytes gave me something like 25% better framerates on my 
hardware (2004 era laptop with ATI), purely from increased rendering speeds.

Does it sound likely that I'll see this sort of improvement on other 
hardware too? Or should I just stick with using colors as floats throughout?

If I do go ahead, I'm not certain how to construct the vbo containing 
mixed types like this. Is there anything in OpenGL.arrays that might 
help, or do I need to brush up on my ctypes-fu to construct an array of 
structs manually?

I'm happy that I do understand how to assign the vertex attribute 
pointers once the vbo is constructed.

     Jonathan

--
Jonathan Hartley      Made of meat.      http://tartley.com
ta...@ta...   +44 7737 062 225   twitter/skype: tartley