The spec says that front-face is true if the value is >0 and false
if it's <0. To make sure that we follow the spec, lets just
subtract 0.5 from our value (llvmpipe did 1 for frontface and 0
otherwise), which will get us a positive num for frontface and
negative for backface.
Signed-off-by: Zack Rusin <za...@vmware.com>
---
src/gallium/drivers/llvmpipe/lp_state_setup.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/gallium/drivers/llvmpipe/lp_state_setup.c
b/src/gallium/drivers/llvmpipe/lp_state_setup.c
index bb5cfc4..cecfbce 100644
--- a/src/gallium/drivers/llvmpipe/lp_state_setup.c
+++ b/src/gallium/drivers/llvmpipe/lp_state_setup.c
@@ -182,7 +182,10 @@ emit_facing_coef(struct gallivm_state *gallivm,
LLVMValueRef a0_0 = args->facing;
LLVMValueRef a0_0f = LLVMBuildSIToFP(builder, a0_0, float_type, "");
LLVMValueRef zero = lp_build_const_float(gallivm, 0.0);
- LLVMValueRef a0 = vec4f(gallivm, a0_0f, zero, zero, zero, "facing");
+ LLVMValueRef face_val = LLVMBuildFSub(builder, a0_0f,
+ lp_build_const_float(gallivm, 0.5),
+ "");
+ LLVMValueRef a0 = vec4f(gallivm, face_val, zero, zero, zero, "facing");
LLVMValueRef zerovec = vec4f_from_scalar(gallivm, zero, "zero");
store_coef(gallivm, args, slot, a0, zerovec, zerovec);
--
1.7.10.4
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