diff options
authorKenneth Graunke <>2012-08-13 00:35:41 -0700
committerKenneth Graunke <>2012-08-13 19:16:38 -0700
commit605f964d5cc7016fc74e0563829fa794da845c20 (patch)
parent43e3a7533d5537e48cef23588131dd25d938ee4b (diff)
mesa: Use GLdouble for depthMax in final unpack conversions.
The final step of _mesa_unpack_depth_span is to take the temporary GLfloat depth values and convert them to the desired format. When converting to GL_UNSIGNED_INTEGER with depthMax > 0xffffff, we use double-precision math to avoid overflow and precision problems. Or at least that's the idea. Unfortunately GLdouble z = depthValues[i] * (GLfloat) depthMax; actually causes single-precision multiplication, since both operands are GLfloats. Casting depthMax to GLdouble causes the scaling to be done with double-precision math. Fixes a regression in oglconform's depth-stencil test since c60ac7b17993d28af65b04f9bbbf3ee74c35358c, where the expected and actual values differed slightly. For example, 0xcfa7a6 vs. 0xcfa7a4. Bugzilla: Signed-off-by: Kenneth Graunke <>
1 files changed, 1 insertions, 1 deletions
diff --git a/src/mesa/main/pack.c b/src/mesa/main/pack.c
index 83192c1574c..672a467aa1c 100644
--- a/src/mesa/main/pack.c
+++ b/src/mesa/main/pack.c
@@ -4913,7 +4913,7 @@ _mesa_unpack_depth_span( struct gl_context *ctx, GLuint n,
else {
/* need to use double precision to prevent overflow problems */
for (i = 0; i < n; i++) {
- GLdouble z = depthValues[i] * (GLfloat) depthMax;
+ GLdouble z = depthValues[i] * (GLdouble) depthMax;
if (z >= (GLdouble) 0xffffffff)
zValues[i] = 0xffffffff;