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

[Roland Scheidegger]

Am 25.04.2013 19:44, schrieb Zack Rusin:
> ----- Original Message -----
>> Am 24.04.2013 00:58, schrieb 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]);
>>>     }
>>>  
>>>  }
>>>
>>
>> The change itself looks good but I think there's quite some more
>> assumptions that position must be output zero elsewhere.
> 
> Nothing that I could find in draw. If you're aware of something I'd like to know.

Hmm yes looks like that's not really the case anymore. Maybe you fixed
those already :-).

Roland