Properly plumbing layout for global varyings. (#6198)

* Properly plumbing layout for global varyings.

* Fix test.

1 files changed, 28 insertions, 0 deletions

diff --git a/source/slang/slang-parameter-binding.cpp b/source/slang/slang-parameter-binding.cpp
index 825e0f4af..55c487e4e 100644
--- a/source/slang/slang-parameter-binding.cpp
+++ b/source/slang/slang-parameter-binding.cpp
@@ -712,6 +712,15 @@ RefPtr<TypeLayout> getTypeLayoutForGlobalShaderParameter(
         return createTypeLayoutWith(layoutContext, specializationConstantRule, type);
     }
 
+    if (varDecl->hasModifier<InModifier>())
+    {
+        return createTypeLayoutWith(layoutContext, rules->getVaryingInputRules(), type);
+    }
+    else if (varDecl->hasModifier<OutModifier>())
+    {
+        return createTypeLayoutWith(layoutContext, rules->getVaryingOutputRules(), type);
+    }
+
     // TODO(tfoley): there may be other cases that we need to handle here
 
     // An "ordinary" global variable is implicitly a uniform
@@ -1120,6 +1129,25 @@ static void addExplicitParameterBindings_GLSL(
             return;
     }
 
+    if (auto foundVaryingInput = typeLayout->FindResourceInfo(LayoutResourceKind::VaryingInput))
+    {
+        info[kResInfo].resInfo = foundVaryingInput;
+
+        if (auto layoutAttr = varDecl.getDecl()->findModifier<GLSLLocationAttribute>())
+            info[kResInfo].semanticInfo.index = layoutAttr->value;
+        else
+            return;
+    }
+    if (auto foundVaryingOutput = typeLayout->FindResourceInfo(LayoutResourceKind::VaryingOutput))
+    {
+        info[kResInfo].resInfo = foundVaryingOutput;
+
+        if (auto layoutAttr = varDecl.getDecl()->findModifier<GLSLLocationAttribute>())
+            info[kResInfo].semanticInfo.index = layoutAttr->value;
+        else
+            return;
+    }
+
     // For remaining cases, we only want to apply GLSL-style layout modifers
     // when compiling for Khronos and WGSL targets.
     //