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Want to use SW Vertex Shaders, confused.

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Because I need to do lots of work to generate all my vertices every frame from compressed data, I believe a SW vertex shader may be quicker than doing it myself, due to SIMD optimisations (and obviously far quicker on shader-equipped hardware). However because I''m using this on non-shader cards, I need to know how to use a custom vertex shader with the default pixel shader utilised by the fixed function pipeline. Can someone tell me where to output the vertex data to (texcoords, colours, positions etc) so the pixel shader knows what to do with it please?
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oD0 and oD1 are D3DTA_DIFFUSE and D3DTA_SPECULAR
oT0 to oT7 are the texture coordinates after processing

There isn''t really anything else to know past what''s in the docs - what comes out of a shader "just works" with fixed function fragment (pixel) processing.
You output the post transform positions in oPos, after stuff like clipping the chip/D3D assembles these to form polygons - oD0 and oD1 and the coordinates are always interpolated across the polygon.

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Simon O''Connor
Creative Asylum Ltd
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Does my idea sound good to anyone?

My decompression per vertex, per frame involves maybe 10 multiplies and a few adds, possibly a test or two.
Is a software Vshader likely to beat my SW code on MMX,SSE etc machines?

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