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

[Nicolas R. <Nic...@in...>]

Yes you can (see numpy record arrays)

Z = numpy.zeros(100, 
       dtype = [('position','f4',3)), ('normal','f4',3), ('color','uint8',4)] )

(see  example posted previously).

Nicolas


On Feb 3, 2011, at 6:49 PM, Stephen Hopkins wrote:

> I dont think its possible to have 2 different data types in the same array. IF you've been using Numpy, each array has a type like float32,
> 
> zeros(3 * numVertices + 4 * numVertices , dtype=float32)
> 
> you could make 2 vbos and bind 2 vertexAttribPointers
> 
> colorVBO = zeros(4 * numVertices, dtype="whatever is unsigned byte")
> vertexVBO = zeros(3*numVertices, dtype="float32")
> 
> On Thu, Feb 3, 2011 at 3:49 AM, Jonathan Hartley <ta...@ta...> wrote:
> 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
> 
> 
> 
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