2008/6/16 Brian Paul <[EMAIL PROTECTED]>: > H. Verbeet wrote: >> >> ------------------------------------------------------------------------ >> >> Vertex programs replace fog coord generation, but not vertex fog >> application. This also means the fog stage should be run after the vertex >> program stage. > > Hmmm, can you point me to where this is stated in the vertex program > extension spec? I don't recall seeing this before. >
Although it doesn't explicitly say vertex programs don't replace vertex fog application, it's implied by the following parts of the spec: > Section 2.14.3.4, Vertex Program Results ... > If a result variable binding matches "result.fogcoord", updates to the "x" > component of the result variable set the transformed vertex's fog > coordinate. Updates to the "y", "z", and "w" components of the result > variable have no effect. ... > Additions to Chapter 3 of the OpenGL 1.3 Specification (Rasterization) ... > Modify Section 3.10, Fog (p. 154) > > (modify second paragraph) This factor f may be computed according to one > of three equations: > > f = exp(-d*c), (3.24) > f = exp(-(d*c)^2), or (3.25) > f = (e-c)/(e-s) (3.26) > > If vertex program mode is enabled or if the fog source (as defined below) > is FOG_COORDINATE_EXT, then c is the fragment's fog coordinate. > Otherwise, the c is the eye-coordinate distance from the eye, (0,0,0,1) in > eye-coordinates, to the fragment center. ... Henri ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Mesa3d-dev mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/mesa3d-dev
