Am 22.06.2011 16:11, schrieb Brian Paul: > On 06/22/2011 04:18 AM, Dave Airlie wrote: >> I don't suppose anyone could contribute a comment on why somethings >> check ctx->VertexProgram._Current, >> and others check ctx->VertexProgram._Enabled > > The former may point to a GLSL shader/program, a > GL_NV/ARB_vertex_program program or a shader derived from fixed-function > state. > > The later will only be true when a GL_NV/ARB_vertex_program program is > enabled and valid (GL_VERTEX_PROGRAM_ARB is enabled and the user's > program compiled successfully). > > I haven't looked at all the places where _Enabled or _Current is used, > but there is a difference in what they mean. > > >> By the looks of it the 0/POS attrib + the overlapping/16-31 ones check >> _Current >> and the others all check _Enabled, to me it would make some sense at >> least if 0 >> was consistent with the others, but maybe someone knows what is correct. > > The confusion probably goes all the way back to the ARB's unfortunate > inability to reconcile NV's vs. ATI's different handling of generic > vertex arrays. NV used aliasing while ATI didn't so the ARB extension > made it optional (a mess). Plus, I think there was some minor > difference in GL_ARB_vertex_program vs. GL_ARB_vertex_shaders w.r.t. > generic vertex arrays.
Wasn't the difference just that ARB_vertex_shader made it non-aliasing instead of undefined aliasing, or was there more to it... Roland _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
