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authorBrian Paul <brian.paul@tungstengraphics.com>2008-04-23 11:37:49 -0600
committerBrian Paul <brian.paul@tungstengraphics.com>2008-04-23 11:38:41 -0600
commitba47aabc9868b410cdfe3bc8b6d25a44a598cba2 (patch)
tree8b930a9a5da92878d69a69ede0062caaee80ef8d /src/mesa/shader
parent5d873c87186fd3a59b46b4e1e0c987120aa961a7 (diff)
gallium: fix potential divide by zero in fog computation
It's legal for Fog.Start == Fog.End and conformance testing does so.
Diffstat (limited to 'src/mesa/shader')
-rw-r--r--src/mesa/shader/prog_statevars.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/src/mesa/shader/prog_statevars.c b/src/mesa/shader/prog_statevars.c
index 45352d30b5..eee4d2d925 100644
--- a/src/mesa/shader/prog_statevars.c
+++ b/src/mesa/shader/prog_statevars.c
@@ -253,7 +253,8 @@ _mesa_fetch_state(GLcontext *ctx, const gl_state_index state[],
value[0] = ctx->Fog.Density;
value[1] = ctx->Fog.Start;
value[2] = ctx->Fog.End;
- value[3] = 1.0F / (ctx->Fog.End - ctx->Fog.Start);
+ value[3] = (ctx->Fog.End == ctx->Fog.Start)
+ ? 1.0 : 1.0F / (ctx->Fog.End - ctx->Fog.Start);
return;
case STATE_CLIPPLANE:
{
@@ -424,8 +425,9 @@ _mesa_fetch_state(GLcontext *ctx, const gl_state_index state[],
* exp: 2^-(density/ln(2) * fogcoord)
* exp2: 2^-((density/(ln(2)^2) * fogcoord)^2)
*/
- value[0] = -1.0F / (ctx->Fog.End - ctx->Fog.Start);
- value[1] = ctx->Fog.End / (ctx->Fog.End - ctx->Fog.Start);
+ value[0] = (ctx->Fog.End == ctx->Fog.Start)
+ ? 1.0 : -1.0F / (ctx->Fog.End - ctx->Fog.Start);
+ value[1] = ctx->Fog.End * -value[0];
value[2] = ctx->Fog.Density * ONE_DIV_LN2;
value[3] = ctx->Fog.Density * ONE_DIV_SQRT_LN2;
return;