Mesa (8.0): mesa: Use GLdouble for depthMax in final unpack conversions.
Kenneth Graunke
kwg at kemper.freedesktop.org
Fri Aug 17 06:54:40 UTC 2012
Module: Mesa
Branch: 8.0
Commit: 57295009e895b1d39c083c3873fdeaf4dadd778b
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=57295009e895b1d39c083c3873fdeaf4dadd778b
Author: Kenneth Graunke <kenneth at whitecape.org>
Date: Mon Aug 13 00:35:41 2012 -0700
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 basic.read.ds test
since c60ac7b17993d28af65b04f9bbbf3ee74c35358c, where the expected and
actual values differed slightly. For example, 0xcfa7a6 vs. 0xcfa7a4.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=49772
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
src/mesa/main/pack.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/src/mesa/main/pack.c b/src/mesa/main/pack.c
index 4b0ee79..f3f9283 100644
--- a/src/mesa/main/pack.c
+++ b/src/mesa/main/pack.c
@@ -4900,7 +4900,7 @@ _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;
else
More information about the mesa-commit
mailing list