draw/llvm: fix viewport transformations

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 <[email protected]>
Reviewed-by: José Fonseca <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>

1 files changed, 5 insertions, 4 deletions

diff --git a/src/gallium/auxiliary/draw/draw_llvm.c b/src/gallium/auxiliary/draw/draw_llvm.c
index 71e2c32f4c3..d2821a14633 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]);
    }
 
 }