From 13ff0bd345990c0fdfb7b52ebd5339cddb04889e Mon Sep 17 00:00:00 2001 From: Tim Foley Date: Wed, 3 Mar 2021 11:45:39 -0800 Subject: Add GLSL/SPIR-V support got GetAttributeAtVertex (#1733) This change allows varying fragment shader inputs to be declared in a way that allows the `GetAttributeAtVertex` operation to compile to valid code for both D3D and GLSL/SPIR-V/Vulkan. The key is that rather than just use ordinary `nointerpolation`-qualified inputs the code must declare these varying inputs with a new `pervertex` qualifier that marks them as *only* being usable with `GetAttributeAtVertex`. The `pervertex`-tagged inputs then translate to GLSL inputs using the `pervertexNV` qualifier Note that this change does *not* include any enforcement of the requirements around how these qualifiers are used (and the compiler doesn't have enforcement for the existing operations like `EvaluateAttributeAtCentroid`). The underlying problem is that the inerpolation-mode qualifiers and explicit interpolation functions in HLSL constitute a kind of rate-qualified type system, but without any systematic rules. It seems wasteful to encode a bunch of ad hoc rules for this stuff as special cases in the compiler when the clear right answer is to implement a systematic approach to rates. --- source/slang/slang-lower-to-ir.cpp | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'source/slang/slang-lower-to-ir.cpp') diff --git a/source/slang/slang-lower-to-ir.cpp b/source/slang/slang-lower-to-ir.cpp index ef4cb98ec..fb9fc70fd 100644 --- a/source/slang/slang-lower-to-ir.cpp +++ b/source/slang/slang-lower-to-ir.cpp @@ -1820,6 +1820,10 @@ void addVarDecorations( { builder->addInterpolationModeDecoration(inst, IRInterpolationMode::NoInterpolation); } + else if(as(mod)) + { + builder->addInterpolationModeDecoration(inst, IRInterpolationMode::PerVertex); + } else if(as(mod)) { builder->addInterpolationModeDecoration(inst, IRInterpolationMode::NoPerspective); -- cgit v1.2.3