Mesh shader support (#2464)

* Add gdb generated files to .gitignore

* Switch to c++17

TODO: Ellie update coding style doc

* WIP mesh shaders

* Add MeshOutputType and mesh output decorations

* Lift array type layout creation out of _createTypeLayout

in preparation for sharing it elsewhere

* Initial pass at GLSL legalization for mesh shaders

* Create output types for builtin mesh outputs

This should be rendered as an out paramter block

* Handle writes to member fields in mesh shader output

* Per primitive output from mesh shaders

* Add mesh shader tests

* Redeclare mesh output builtins

* Remove unused instruction

* Emit explicit mesh output max max size

* Add unimplemented warning for array members in mesh output

* Implement mesh output splitting for GLSL in terms of getSubscriptVal

* Allow HLSL syntax for mesh output modifiers

* Improve error messages for mesh output

* Add test for HLSL style mesh output syntax

* Emit explicit mesh output indices max size

* HLSL generation support for mesh shaders

* Better errors for mesh shader misuse

* Neaten comments

* Regenerate vs2019 project files

* Fix build on vs2019

* Retreat on c++17

Will make the change in a separate PR

* slang-glslang binary dep 11.10.0 -> 11.12.0-32

* Fixes for msvc compiler

* Update msvc project

1 files changed, 27 insertions, 0 deletions

diff --git a/source/slang/slang-parameter-binding.cpp b/source/slang/slang-parameter-binding.cpp
index 07875c183..db323ff6e 100644
--- a/source/slang/slang-parameter-binding.cpp
+++ b/source/slang/slang-parameter-binding.cpp
@@ -1912,6 +1912,33 @@ static RefPtr<TypeLayout> processEntryPointVaryingParameter(
 
         return arrayTypeLayout;
     }
+    else if( auto meshOutputType = as<MeshOutputType>(type) )
+    {
+        // TODO: Ellie, revisit
+        // Note: Bad Things will happen if we have an array input
+        // without a semantic already being enforced.
+
+        // We use the first element to derive the layout for the element type
+        auto elementTypeLayout = processEntryPointVaryingParameter(context, meshOutputType->getElementType(), state, varLayout);
+
+        RefPtr<ArrayTypeLayout> arrayTypeLayout = new ArrayTypeLayout();
+        arrayTypeLayout->elementTypeLayout = elementTypeLayout;
+        arrayTypeLayout->type = arrayType;
+
+        // TODO: Ellie, this is probably not the right place to handle this
+        // On GLSL the indices type is built in and as such doesn't consume
+        // resources.
+        if(!isKhronosTarget(context->getTargetRequest()) || !as<IndicesType>(type))
+        {
+            for (auto rr : elementTypeLayout->resourceInfos)
+            {
+                // TODO: Ellie, explain why only one slot is consumed here
+                arrayTypeLayout->findOrAddResourceInfo(rr.kind)->count = rr.count;
+            }
+        }
+
+        return arrayTypeLayout;
+    }
     // Ignore a bunch of types that don't make sense here...
     else if (auto textureType = as<TextureType>(type)) { return nullptr;  }
     else if(auto samplerStateType = as<SamplerStateType>(type)) { return nullptr;  }