software and mixed vertex processing

On the mixed device are you using hardware or software vertex processing.

If you see a difference between D3DCREATE_SOFTWARE_VERTEXPROCESSING and D3DCREATE_MIXED_VERTEXPROCESSING WITH vertex processing set to SOFTWARE (i.e. the render state and the VBs), then that is VERY odd.

If however, you see some *small* differences between software and hardware vertex processing, then that is totally normal because hardware DOES work in a slightly different way and uses certain optimisations (e.g. such as using fixed point numbers). If you''re using this for multipass or expecting say software tesselated patches to line up with hardware points then that won''t ever happen perfectly!...

If you only see this after switching between hardware and software vertex processing on a mixed mode device then bear in mind that the switch is a VERY major thing (you should do it once per frame at most really) - you WILL have to reset the values of all render states which affect what you''re doing - mainly the vertex processing states, but also some of the pixel processing states which will affect things like subpixel accuracy etc.


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Simon O''Connor
Creative Asylum Ltd
www.creative-asylum.com