Mesa (master): mesa: Set correct values for range/ precision of shader integer types

[Ian Romanick]

Module: Mesa
Branch: master
Commit: 04dca296e0a5e5ffbb8acb699e013a23ebd7b645
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=04dca296e0a5e5ffbb8acb699e013a23ebd7b645

Author: Ian Romanick <ian.d.romanick at intel.com>
Date:   Thu Jan 20 12:05:38 2011 -0800

mesa: Set correct values for range/precision of shader integer types

---

 src/mesa/main/context.c |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/mesa/main/context.c b/src/mesa/main/context.c
index fe370fa..e017939 100644
--- a/src/mesa/main/context.c
+++ b/src/mesa/main/context.c
@@ -534,8 +534,17 @@ init_program_limits(GLenum type, struct gl_program_constants *prog)
    prog->MediumFloat.RangeMax = 127;
    prog->MediumFloat.Precision = 23;
    prog->LowFloat = prog->HighFloat = prog->MediumFloat;
-   /* assume ints are stored as floats for now */
-   prog->LowInt = prog->MediumInt = prog->HighInt = prog->MediumFloat;
+
+   /* Assume ints are stored as floats for now, since this is the least-common
+    * denominator.  The OpenGL ES spec implies (page 132) that the precision
+    * of integer types should be 0.  Practically speaking, IEEE
+    * single-precision floating point values can only store integers in the
+    * range [-0x01000000, 0x01000000] without loss of precision.
+    */
+   prog->MediumInt.RangeMin = 24;
+   prog->MediumInt.RangeMax = 24;
+   prog->MediumInt.Precision = 0;
+   prog->LowInt = prog->HighInt = prog->MediumInt;
 }