Pierre Boulenguez wrote:
> Dear Mesa team,
> 
> First thank you for your work on Mesa and it's open sourcing.
> 
> I am looking for the GL_PERSPECTIVE_CORRECTION_HINT implementation details.
> 
> If I am correct, as of openGL 2.1, this hint is of no more use as all 
> interpolations (color, texture coordinates, glsl varying vertex 
> attributes) are in a perspectivly correct form.

That's actually not the case yet in Mesa.  Only texcoords and varying 
vars are perspective corrected at this time.  Thanks for reminding me 
about that.


> I grep'ed "GL_PERSPECTIVE_CORRECTION_HINT" on the 6.3.2 and 6.5.2 source 
> trees, and followed the thread but was unable to conclude.
> 
> So am I asking if would point to me the relevant file/functions to 
> search for this interpolant.

The only place where GL_PERSPECTIVE_CORRECTION_HINT is used is in a few 
semi-optimized triangle rasterizer functions.  If you set 
GL_PERSPECTIVE_CORRECTION_HINT to GL_FASTEST and set some other state 
appropriately texcoords will be interpolated w/ integers w/out 
perspective correctsion.  See src/mesa/swrast/s_triangle.c

Otherwise, texcoords are always perspective corrected.

-Brian

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