This fixes a numerical precision issue that was causing two CTS
failures:
ES31-CTS.blend_equation_advanced.blend_specific.GL_COLORBURN_KHR
ES31-CTS.blend_equation_advanced.blend_all.GL_COLORBURN_KHR_all_qualifier
When blending with GL_COLORDODGE_KHR and these colors:
dst = <0.372549027, 0.372549027, 0.372549027, 0.372549027>
src = <0.09375, 0.046875, 0.0, 0.375>
the normalized dst value became 0.99999994 (due to imprecisions in the
alpha scaling, presumably), which failed the dst >= 1.0 comparison.
The blue channel would then fall through to the dst < 1.0 && src >= 0
comparison, which was true, since src.b == 0. This produced a factor
of 0.0 instead of 1.0.
To work around this, compare with 1.0 - FLT_EPSILON.
Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
---
src/compiler/glsl/lower_blend_equation_advanced.cpp | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/compiler/glsl/lower_blend_equation_advanced.cpp
b/src/compiler/glsl/lower_blend_equation_advanced.cpp
index a998df1..f8b0261 100644
--- a/src/compiler/glsl/lower_blend_equation_advanced.cpp
+++ b/src/compiler/glsl/lower_blend_equation_advanced.cpp
@@ -28,6 +28,7 @@
#include "program/prog_instruction.h"
#include "program/prog_statevars.h"
#include "util/bitscan.h"
+#include <float.h>
using namespace ir_builder;
@@ -101,7 +102,7 @@ blend_colorburn(ir_variable *src, ir_variable *dst)
* 1 - min(1,(1-Cd)/Cs), if Cd < 1 and Cs > 0
* 0, if Cd < 1 and Cs <= 0
*/
- return csel(gequal(dst, imm3(1)), imm3(1),
+ return csel(gequal(dst, imm3(1 - FLT_EPSILON)), imm3(1),
csel(lequal(src, imm3(0)), imm3(0),
sub(imm3(1), min2(imm3(1), div(sub(imm3(1), dst), src)))));
}
--
2.9.3
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