Re: clipping planes bypassed in CG vertex shaders

true, thx, RIX

----- Original Message ----- 
To: "Multiple recipients of list OPENGL-GAMEDEV-L" 
<[email protected]>
Sent: Monday, May 23, 2005 11:18 PM


> No, as previously explained by others, there's just no way you can 
> possibly clip before the vertex shader. Since the final position of the 
> vertex is computed by it, how would you know whether and how to clip until 
> you've run it?
>
> Tony Cox - Development Manager
> Studio ZR, Microsoft Game Studios
>
> -----Original Message-----
> Sent: Monday, May 23, 2005 8:03 PM
> To: Multiple recipients of list OPENGL-GAMEDEV-L
>
> Guys, thanks for all comments.
>
> Well, clipping must be applied per primitive (i.e. triangle)... so, it 
> could
> be done before shading... Primitives can be removed, or clipped (it could
> add new verteces). So, in vertex shader, we can receive unclipped or new
> verteces, and we can play with them as we need (modify: move, translate,
> whatever). I think, it is good.
>
> After vertex shader, clipping even works, but it could not be good enough,
> because we do not want to waste gpu time shading verteces of objects which
> are going to be removed by clipping.
>
> Well, anyway, the point is that user clipping planes are disable in
> programmable pipeline (at least in my fx5200 and fx6800). I think, it is a
> little damn for some programmers.
>
> Regards
> Rhadamés
>
> ibing).
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> -- 
> Author: Tony Cox
>  INET: [email protected]
>
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