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| author | Tim Foley <tfoleyNV@users.noreply.github.com> | 2021-03-03 11:45:39 -0800 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2021-03-03 11:45:39 -0800 |
| commit | 13ff0bd345990c0fdfb7b52ebd5339cddb04889e (patch) | |
| tree | ae3773d4f3475439a55603007b3908e31c6c31fb /source/slang/core.meta.slang | |
| parent | d6ae67160c33460bf952c9959077dc481a16eca2 (diff) | |
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.
Diffstat (limited to 'source/slang/core.meta.slang')
| -rw-r--r-- | source/slang/core.meta.slang | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/source/slang/core.meta.slang b/source/slang/core.meta.slang index de78229a9..39ee702c6 100644 --- a/source/slang/core.meta.slang +++ b/source/slang/core.meta.slang @@ -17,6 +17,16 @@ syntax constexpr : ConstExprModifier; // visible at the global-memory scope syntax globallycoherent : GloballyCoherentModifier; +/// Modifier to disable inteprolation and force per-vertex passing of a varying attribute. +/// +/// When a varying attribute passed to the fragment shader is marked `pervertex`, it will +/// not be interpolated during rasterization (similar to `nointerpolate` attributes). +/// Unlike a plain `nointerpolate` attribute, this modifier indicates that the attribute +/// should *only* be acccessed through the `GetAttributeAtVertex()` operation, so access its +/// distinct per-vertex values. +/// +syntax pervertex : PerVertexModifier; + // A type that can be used as an operand for builtins [sealed] [builtin] |