Testcase for Shader reflection with USD

In this test we use a materialx document with two surfacematerial. We generate shaders for each of the surfaces and use reflection to report the input paths. Notice that the input paths for both surface materials are identical though the generated shader code isn't
autodesk-forks · Sep 6, 2023 · ab218c0 · ab218c0
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diff --git a/resources/Materials/TestSuite/usd_usage/surfacematerial.mtlx b/resources/Materials/TestSuite/usd_usage/surfacematerial.mtlx
@@ -0,0 +1,18 @@
+<materialx version="1.38" colorspace="lin_rec709">
+  <!-- node shared between two surface materials-->
+  <UsdPreviewSurface name="SR_plastic" type="surfaceshader">
+    <input name="diffuseColor" type="color3" value="0.10470402, 0.24188282, 0.81800002" />
+    <input name="roughness" type="float" value="0.32467532157897949" />
+    <input name="ior" type="float" value="1.5" />
+  </UsdPreviewSurface>
+
+  <!-- 1st surfacematerial -->
+  <surfacematerial name="USD_PlasticOne" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="SR_plastic" />
+  </surfacematerial>
+
+  <!-- 2nd surfacematerial -->
+  <surfacematerial name="USD_PlasticTwo" type="material">
+    <input name="surfaceshader" type="surfaceshader" nodename="SR_plastic" />
+  </surfacematerial>  
+</materialx>
diff --git a/source/MaterialXTest/MaterialXGenShader/GenShader.cpp b/source/MaterialXTest/MaterialXGenShader/GenShader.cpp
@@ -265,6 +265,79 @@ TEST_CASE("GenShader: Deterministic Generation", "[genshader]")
 #endif
 }
 
+void testShaderReflection(mx::DocumentPtr libraries, mx::GenContext& context)
+{
+    mx::FileSearchPath searchPath = mx::getDefaultDataSearchPath();
+    mx::FilePath testFile = searchPath.find("resources/Materials/TestSuite/usd_usage/surfacematerial.mtlx");
+
+    mx::StringVec sourceCode(2);
+
+    mx::DocumentPtr testDoc = mx::createDocument();
+    mx::readFromXmlFile(testDoc, testFile);
+    testDoc->importLibrary(libraries);
+
+    mx::string testSurfaceOne = "USD_PlasticOne";
+    mx::ElementPtr element = testDoc->getChild(testSurfaceOne);
+    CHECK(element);
+
+    mx::ShaderPtr shaderOne = context.getShaderGenerator().generate(testSurfaceOne, element, context);
+    sourceCode[0] = shaderOne->getSourceCode();
+
+    mx::string testSurfaceTwo = "USD_PlasticTwo";
+    element = testDoc->getChild(testSurfaceTwo);
+    CHECK(element);
+
+    mx::ShaderPtr shaderTwo = context.getShaderGenerator().generate(testSurfaceTwo, element, context);
+    sourceCode[1] = shaderTwo->getSourceCode();
+
+    // Shader code is different
+    CHECK(sourceCode[0] != sourceCode[1]);
+
+    // Check paths
+    mx::ShaderStage& stage1 = shaderOne->getStage(mx::Stage::PIXEL);
+    mx::VariableBlock& block1 = stage1.getUniformBlock(mx::HW::PUBLIC_UNIFORMS);
+
+    printf("Shader one input paths:\n");
+    for (mx::ShaderPort* variable : block1.getVariableOrder())
+    {
+        std::string parameterPath = variable->getPath();
+        if (!parameterPath.empty())
+            printf("%s\n", parameterPath.c_str());
+    }
+
+    mx::ShaderStage& stage2 = shaderTwo->getStage(mx::Stage::PIXEL);
+    mx::VariableBlock& block2 = stage2.getUniformBlock(mx::HW::PUBLIC_UNIFORMS);
+    printf("Shader two input paths:\n");
+    for (mx::ShaderPort* variable : block2.getVariableOrder())
+    {
+        std::string parameterPath = variable->getPath();
+        if (!parameterPath.empty())
+            printf("%s\n", parameterPath.c_str());
+    }
+}
+
+TEST_CASE("GenShader: Shader reflection", "[genshader]")
+{
+    mx::FileSearchPath searchPath = mx::getDefaultDataSearchPath();
+    mx::DocumentPtr libraries = mx::createDocument();
+    mx::loadLibraries({ "libraries" }, searchPath, libraries);
+
+#ifdef MATERIALX_BUILD_GEN_GLSL
+    {
+        mx::GenContext context(mx::GlslShaderGenerator::create());
+        context.registerSourceCodeSearchPath(searchPath);
+        testShaderReflection(libraries, context);
+    }
+#endif
+#ifdef MATERIALX_BUILD_GEN_MSL
+    {
+        mx::GenContext context(mx::MslShaderGenerator::create());
+        context.registerSourceCodeSearchPath(searchPath);
+        testShaderReflection(libraries, context);
+    }
+#endif
+}
+
 void checkPixelDependencies(mx::DocumentPtr libraries, mx::GenContext& context)
 {
     mx::FileSearchPath searchPath = mx::getDefaultDataSearchPath();