From b487516880f56fd69ff76bf7cb3f0f1711bc356d Mon Sep 17 00:00:00 2001 From: Tim Foley Date: Wed, 29 Nov 2017 11:45:15 -0800 Subject: Add API to query stage of varying parameter (#302) Fixes #301 The problem here is that if you have input GLSL code like: ```glsl // example.vs in vec3 pos; ``` and: ```glsl // example.fs in vec3 worldPos; ``` Then both `pos` and `worldPos` are reflected as global variables (parameters of the *program*), which both get bound to "varying input" resources, but there is no way to tell through the API that `pos` is a vertex parameter while `worldPos` is a fragment one. The original request in issue #301 was to expose parameters like this not as a global variables, but rather as parameters of the entry point in their specific file. That is, treat it as if the user had written, e.g.: ```glsl // example.vs void vsMain(in vec3 pos) { ... } ``` Doing that would unify the GLSL and HLSL/Slang cases a bit, but would require the Slang reflection API to lie about the structure of code the user wrote. At a more basic level, that would have been hard to implement because the current reflection API just exposes the underlying AST, and the AST *needs* to leave `pos` at the global scope so that when we go and spit GLSL back out we retain the original structure. This PR implements a more simplistic solution, where the user is allowed to query the stage that a varying parameter "belongs" to. For right now I'm only enabling this to work for varying parameters (but it doesn't care if they are entry-point or global-scope varyings). Despite what I said on #301, this should work for both the top-level parameter's variable layout, *and* any variable layouts for fields within its type reflection. In terms of implementation, I took the simple but wasteful route: every `VarLayout` now has a `stage` field that is by default initialized to `SLANG_STAGE_NONE`. When collecting varying parameters, I take advantage of the fact that everything bottlenecks through `processEntryPointParameter()` which takes an `EntryPointParameterState` so that I can set the `VarLayout::stage` field for any varying parameter in one place. While I was making this change, I also did a bit of cleanup so that the "official" names for the varying parameter categories are `VARYING_INPUT` and `VARYING_OUTPUT`, with `VERTEX_INPUT` and `FRAGMENT_OUTPUT` being "deprecated" in principle. I didn't do the bulk rename inside the codebase yet. --- source/slang/reflection.cpp | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'source/slang/reflection.cpp') diff --git a/source/slang/reflection.cpp b/source/slang/reflection.cpp index 14199f126..a1ea3ff72 100644 --- a/source/slang/reflection.cpp +++ b/source/slang/reflection.cpp @@ -666,6 +666,36 @@ SLANG_API size_t spReflectionVariableLayout_GetSemanticIndex(SlangReflectionVari return varLayout->semanticIndex; } +SLANG_API SlangStage spReflectionVariableLayout_getStage( + SlangReflectionVariableLayout* inVarLayout) +{ + auto varLayout = convert(inVarLayout); + if(!varLayout) return SLANG_STAGE_NONE; + + // A parameter that is not a varying input or output is + // not considered to belong to a single stage. + // + // TODO: We might need to reconsider this for, e.g., entry + // point parameters, where they might be stage-specific even + // if they are uniform. + if (!varLayout->FindResourceInfo(Slang::LayoutResourceKind::VaryingInput) + && !varLayout->FindResourceInfo(Slang::LayoutResourceKind::VaryingOutput)) + { + return SLANG_STAGE_NONE; + } + + // TODO: We should find the stage for a variable layout by + // walking up the tree of layout information, until we find + // something that has a definitive stage attached to it (e.g., + // either an entry point or a GLSL translation unit). + // + // We don't currently have parent links in the reflection layout + // information, so doing that walk would be tricky right now, so + // it is easier to just bloat the representation and store yet another + // field on every variable layout. + return (SlangStage) varLayout->stage; +} + // Shader Parameter Reflection -- cgit v1.2.3