From bd77f517585baa1dba70e7cf260828f0d772e61a Mon Sep 17 00:00:00 2001 From: Henri Verbeet Date: Sat, 31 Aug 2013 11:50:16 +0200 Subject: [PATCH] mesa: Properly set the fog scale (gl_Fog.scale) to +INF when fog start and end are equal. This was originally introduced by commit ba47aabc9868b410cdfe3bc8b6d25a44a598cba2, but unfortunately the commit message doesn't go into much detail about why +INF would be a problem here. A similar issue exists for STATE_FOG_PARAMS_OPTIMIZED, but allowing infinity there would potentially introduce NaNs where they shouldn't exist, depending on the values of fog end and the fog coord. Since STATE_FOG_PARAMS_OPTIMIZED is only used for fixed function (including ARB_fragment_program with fog option), and the calculation there probably isn't very stable to begin with when fog start and end are close together, it seems best to just leave it alone. This fixes piglit glsl-fs-fogscale, and a couple of Wine D3D tests. No piglit regressions on Cayman. Signed-off-by: Henri Verbeet Tested-by: Brian Paul Reviewed-by: Brian Paul --- src/mesa/program/prog_statevars.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/src/mesa/program/prog_statevars.c b/src/mesa/program/prog_statevars.c index f6073be132a..145c07c6767 100644 --- a/src/mesa/program/prog_statevars.c +++ b/src/mesa/program/prog_statevars.c @@ -256,8 +256,7 @@ _mesa_fetch_state(struct gl_context *ctx, const gl_state_index state[], value[0] = ctx->Fog.Density; value[1] = ctx->Fog.Start; value[2] = ctx->Fog.End; - value[3] = (ctx->Fog.End == ctx->Fog.Start) - ? 1.0f : (GLfloat)(1.0 / (ctx->Fog.End - ctx->Fog.Start)); + value[3] = 1.0f / (ctx->Fog.End - ctx->Fog.Start); return; case STATE_CLIPPLANE: { -- 2.30.2