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

[Stephen H. <sho...@us...>]

And the Z array you posted could be passed as a single vertex attrib
pointer?

On Thu, Feb 3, 2011 at 10:23 AM, Nicolas Rougier
<Nic...@in...>wrote:

>
> 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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>
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