[Mesa-dev] [PATCH 3/5] draw/llvm: fix viewport transformations

[Zack Rusin]

This was a very serious bug. We were always doing the viewport
transformations on the first output of the vertex shader. That means
that every application that was storing position in anything but
OUT[0] was outputing untransformed vertices and had broken output
for whatever it was storing at OUT[0]. Correctly take into
consideration where the vertex position is actually stored.

Signed-off-by: Zack Rusin <zackr at vmware.com>
---
 src/gallium/auxiliary/draw/draw_llvm.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/gallium/auxiliary/draw/draw_llvm.c b/src/gallium/auxiliary/draw/draw_llvm.c
index 594b0ec..bdd24be 100644
--- a/src/gallium/auxiliary/draw/draw_llvm.c
+++ b/src/gallium/auxiliary/draw/draw_llvm.c
@@ -996,18 +996,19 @@ generate_viewport(struct draw_llvm_variant *variant,
    int i;
    struct gallivm_state *gallivm = variant->gallivm;
    struct lp_type f32_type = vs_type;
+   const unsigned pos = draw_current_shader_position_output(variant->llvm->draw);
    LLVMTypeRef vs_type_llvm = lp_build_vec_type(gallivm, vs_type);
-   LLVMValueRef out3 = LLVMBuildLoad(builder, outputs[0][3], ""); /*w0 w1 .. wn*/
+   LLVMValueRef out3 = LLVMBuildLoad(builder, outputs[pos][3], ""); /*w0 w1 .. wn*/
    LLVMValueRef const1 = lp_build_const_vec(gallivm, f32_type, 1.0);       /*1.0 1.0 1.0 1.0*/
    LLVMValueRef vp_ptr = draw_jit_context_viewport(gallivm, context_ptr);
 
    /* for 1/w convention*/
    out3 = LLVMBuildFDiv(builder, const1, out3, "");
-   LLVMBuildStore(builder, out3, outputs[0][3]);
+   LLVMBuildStore(builder, out3, outputs[pos][3]);
 
    /* Viewport Mapping */
    for (i=0; i<3; i++) {
-      LLVMValueRef out = LLVMBuildLoad(builder, outputs[0][i], ""); /*x0 x1 .. xn*/
+      LLVMValueRef out = LLVMBuildLoad(builder, outputs[pos][i], ""); /*x0 x1 .. xn*/
       LLVMValueRef scale;
       LLVMValueRef trans;
       LLVMValueRef scale_i;
@@ -1033,7 +1034,7 @@ generate_viewport(struct draw_llvm_variant *variant,
       out = LLVMBuildFAdd(builder, out, trans, "");
 
       /* store transformed outputs */
-      LLVMBuildStore(builder, out, outputs[0][i]);
+      LLVMBuildStore(builder, out, outputs[pos][i]);
    }
 
 }
-- 
1.7.10.4