On 16.07.2008 16:55, Maciej Cencora wrote:
> Hi,
> 
> I tried implementing GL_ATI_separate_stencil in r300 driver, but I
> faced a problem. With my simple patch http://pastebin.com/m524d1ae7
> r300 driver supports 2 stencil extensions (GL_ATI_separate_stencil and
> GL_EXT_stencil_two_side). Supporting both extensions causes problem in
> _mesa_update_stencil function (main/stencil.c). First condition in
> that function checks if EXT extension is supported, if so sets up
> ctx->Stencil._TestTwoSide properly. If both extensions are available
> and ATI extension is used then ctx->Stencil._TestTwoSide will always
> be false, and that's not what we want. Possibly other functions are
> also affected. Any suggestions how to properly fix this?

Those two extensions are mutually exclusive. I'd suggest you ditch
EXT_stencil_two_side, which is mutually exclusive with OGL 2.0 (nvidia
manages to support both, I suspect they are switching driver behaviour
depending if an app uses one of the new functions of
EXT_stencil_two_side or one of the new stencil functions in OGL 2.0, if
you do both behaviour is not predictable - I doubt such hacks are
appropriate for mesa).
>From a functionality point of view, EXT_stencil_two_side offers the same
functionality as OGL 2.0, whereas ATI_separate_stencil only offers a
subset (which iirc is the same subset the d3d two-sided stencil
functionality offers). I thought though this subset is a perfect match
for r300...

Roland

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