Traversers for samplers layout binding consistency

Apps/Playground/Scripts/config.json

@@ -1,6 +1,17 @@
 {
     "root": "https://cdn.babylonjs.com",
     "tests": [
+        {
+            "title": "Iridescence NME",
+            "playgroundId": "#2FDQT5#1507",
+            "referenceImage": "iridescence-nme.png"
+        },
+        {
+            "title": "NME Multi Build",
+            "playgroundId": "#D8AK3Z#104",
+            "referenceImage": "nme-multi-build.png",
+            "renderCount": 50
+        },
         {
             "title": "EXR Loader",
             "playgroundId": "#4RN0VF#151",

Apps/package.json

@@ -6,11 +6,11 @@
     "getNightly": "node scripts/getNightly.js"
   },
   "dependencies": {
-    "babylonjs": "^7.22.3",
-    "babylonjs-gltf2interface": "^7.22.3",
-    "babylonjs-gui": "^7.22.3",
-    "babylonjs-loaders": "^7.22.3",
-    "babylonjs-materials": "^7.22.3",
+    "babylonjs": "^7.23.0",
+    "babylonjs-gltf2interface": "^7.23.0",
+    "babylonjs-gui": "^7.23.0",
+    "babylonjs-loaders": "^7.23.0",
+    "babylonjs-materials": "^7.23.0",
     "chai": "^4.3.4",
     "jsc-android": "^241213.1.0",
     "mocha": "^9.2.2",

Plugins/NativeEngine/Source/ShaderCompilerD3D.h

@@ -106,6 +106,7 @@ namespace Babylon
         ShaderCompilerTraversers::AssignLocationsAndNamesToVertexVaryingsD3D(program, ids, vertexAttributeRenaming);
         ShaderCompilerTraversers::SplitSamplersIntoSamplersAndTextures(program, ids);
         ShaderCompilerTraversers::InvertYDerivativeOperands(program);
+        ShaderCompilerTraversers::ReassignBindingToSamplers(program);
 
         // clang-format off
         static const spirv_cross::HLSLVertexAttributeRemap attributes[] = {

Plugins/NativeEngine/Source/ShaderCompilerMetal.cpp

@@ -107,7 +107,8 @@ namespace Babylon
         ShaderCompilerTraversers::AssignLocationsAndNamesToVertexVaryingsMetal(program, ids, vertexAttributeRenaming);
         ShaderCompilerTraversers::SplitSamplersIntoSamplersAndTextures(program, ids);
         ShaderCompilerTraversers::InvertYDerivativeOperands(program);
-
+        ShaderCompilerTraversers::ReassignBindingToSamplers(program);
+
         std::string vertexGLSL(vertexSource.data(), vertexSource.size());
         auto [vertexParser, vertexCompiler] = CompileShader(program, EShLangVertex, vertexGLSL);
 

Plugins/NativeEngine/Source/ShaderCompilerTraversers.cpp

@@ -901,6 +901,78 @@ namespace Babylon::ShaderCompilerTraversers
 
             TIntermediate* m_intermediate{};
         };
+
+        /// <summary>
+        ///  https://github.com/BabylonJS/BabylonNative/issues/1411
+        ///  When a same sampler is declared in VS and FS, GLSlang assign a different binding location for VS and FS.
+        ///  Max binding location is 16 so if more than 8 samplers are declared then D3Dcompile will not compile the shader.
+        ///  This is the case for NME shaders for example.
+        ///  The following traverser list samplers from the VS (and their binding location) and set the same binding location 
+        ///  in FS if it's present. If a sampler is present in FS but not in VS, then a binding location id will be used and incremented.
+        ///  potential solution replacements:
+        ///  - do not expose samplers in generated nme shaders (this doesn't fix the issue if samplers are declared in VS and FS for genuine reasons)
+        ///    Apart from potential regressions and more complex TS code, the problem resides in D3D world only.
+        ///  - use spirv optimizer tool to remove unused samplers: it will not fix the issue, binary will be bigger and compilation time will be longer.
+        /// </summary>
+        class ReassignBindingToSamplersTraverser : public TIntermTraverser
+        {
+        public:
+            static void Traverse(TProgram& program)
+            {
+                ReassignBindingToSamplersTraverser reassignBindingToSamplersTraverser{ };
+                program.getIntermediate(EShLangVertex)->getTreeRoot()->traverse(&reassignBindingToSamplersTraverser);
+                reassignBindingToSamplersTraverser.m_fragmentPass = true;
+                program.getIntermediate(EShLangFragment)->getTreeRoot()->traverse(&reassignBindingToSamplersTraverser);
+            }
+
+        protected:
+            void visitSymbol(TIntermSymbol* symbol) override {
+                // Check if the symbol is a sampler
+                const TType& type = symbol->getType();
+                if (type.getBasicType() == EbtSampler) {
+                    TQualifier& qualifier = symbol->getWritableType().getQualifier();
+                    std::string name{symbol->getName().c_str()};
+                    static const std::string suffix = "Texture";
+                    // appends 'Texture' to the name see SamplerSplitterTraverser for differenciation
+                    bool textureEnds = name.size() >= suffix.size() && name.compare(name.size() - suffix.size(), suffix.size(), suffix) == 0;
+                    if (!textureEnds)
+                    {
+                        name += suffix;
+                    }
+                    if (m_fragmentPass)
+                    {
+                        // fragment pass
+                        auto iter = m_samplerLayoutBinding.find(name);
+                        if (iter == m_samplerLayoutBinding.end())
+                        {
+                            qualifier.layoutBinding = ++m_nextLayoutBinding;
+                            m_samplerLayoutBinding[name] = qualifier.layoutBinding;
+                        }
+                        else
+                        {
+                            qualifier.layoutBinding = iter->second;
+                        }
+                    }
+                    else
+                    {
+                        if (qualifier.hasBinding())
+                        {
+                            // vertex pass
+                            m_samplerLayoutBinding[name] = qualifier.layoutBinding;
+                            m_nextLayoutBinding = std::max(m_nextLayoutBinding, qualifier.layoutBinding);
+                        }
+                    }
+                }
+            }
+
+        private:
+            ReassignBindingToSamplersTraverser() 
+            {
+            }
+            std::map<std::string, int> m_samplerLayoutBinding;
+            bool m_fragmentPass{};
+            unsigned int m_nextLayoutBinding{0};
+        };
     }
 
     ScopeT MoveNonSamplerUniformsIntoStruct(TProgram& program, IdGenerator& ids)
@@ -937,4 +1009,9 @@ namespace Babylon::ShaderCompilerTraversers
     {
         InvertYDerivativeOperandsTraverser::Traverse(program);
     }
+
+    void ReassignBindingToSamplers(glslang::TProgram& program)
+    {
+        ReassignBindingToSamplersTraverser::Traverse(program);
+    }
 }

Plugins/NativeEngine/Source/ShaderCompilerTraversers.h

@@ -82,4 +82,6 @@ namespace Babylon::ShaderCompilerTraversers
     /// https://github.com/bkaradzic/bgfx/blob/7be225bf490bb1cd231cfb4abf7e617bf35b59cb/src/bgfx_shader.sh#L44-L45
     /// https://github.com/bkaradzic/bgfx/blob/7be225bf490bb1cd231cfb4abf7e617bf35b59cb/src/bgfx_shader.sh#L62-L65
     void InvertYDerivativeOperands(glslang::TProgram& program);
+
+    void ReassignBindingToSamplers(glslang::TProgram& program);
 }