MaterialX on Metal

Author: Thor Hjalmarsson

build_scripts/build_usd.py

@@ -1574,11 +1574,12 @@ def InstallDraco(context, force, buildArgs):
 ############################################################
 # MaterialX
 
-MATERIALX_URL = "https://github.com/materialx/MaterialX/archive/v1.38.4.zip"
+MATERIALX_URL = "https://github.com/apple/MaterialX/archive/refs/tags/v1.38.6_MetalShadingLaguage.zip"
 
 def InstallMaterialX(context, force, buildArgs):
     with CurrentWorkingDirectory(DownloadURL(MATERIALX_URL, context, force)):
         cmakeOptions = ['-DMATERIALX_BUILD_SHARED_LIBS=ON']
+        cmakeOptions += ['-DMATERIALX_BUILD_TESTS=OFF']
 
         cmakeOptions += buildArgs;
 

pxr/imaging/hdSt/CMakeLists.txt

@@ -20,6 +20,7 @@ if (${PXR_ENABLE_MATERIALX_SUPPORT})
         MaterialXCore
         MaterialXFormat
         MaterialXGenGlsl
+        MaterialXGenMsl
         hdMtlx
     )
     list(APPEND optionalPrivateClasses

pxr/imaging/hdSt/materialXFilter.cpp

@@ -27,6 +27,7 @@
 #include "pxr/imaging/hdSt/package.h"
 #include "pxr/imaging/hdSt/resourceRegistry.h"
 #include "pxr/imaging/hdMtlx/hdMtlx.h"
+#include "pxr/imaging/hgi/tokens.h"
 
 #include "pxr/usd/sdr/registry.h"
 #include "pxr/imaging/hio/glslfx.h"
@@ -103,16 +104,37 @@ R"(
 </materialx>
 )";
 
+mx::GenContext createMaterialXContext(
+                HdSt_MxShaderGenInfo const& mxHdInfo,
+                std::string const& apiName)
+{
+    if(apiName == HgiTokens->Metal)
+        return HdStMaterialXMslShaderGen::create(mxHdInfo);
+    if(apiName == HgiTokens->OpenGL)
+        return HdStMaterialXGlslShaderGen::create(mxHdInfo);
+    else
+    {
+        TF_CODING_ERROR(
+            "MaterialX Shader Generator doesn't support %s API.",
+            apiName.c_str());
+        //return mx::GenContext();
+    }
+}
+
 // Use the given mxDocument to generate the corresponding glsl shader
 // Based on MaterialXViewer Viewer::loadDocument()
 mx::ShaderPtr
 HdSt_GenMaterialXShader(
     mx::DocumentPtr const& mxDoc,
     mx::FileSearchPath const& searchPath,
-    HdSt_MxShaderGenInfo const& mxHdInfo)
+    HdSt_MxShaderGenInfo const& mxHdInfo,
+    std::string const& apiName)
 {
     // Initialize the Context for shaderGen. 
-    mx::GenContext mxContext = HdStMaterialXShaderGen::create(mxHdInfo);
+    mx::GenContext mxContext = createMaterialXContext(mxHdInfo, apiName);
+
+    // USD expects transmission Opacity. Default is changed to TRANSMISSION_REFRACTION
+    mxContext.getOptions().hwTransmissionRenderMethod = mx::TRANSMISSION_OPACITY;
 
 #if MATERIALX_MAJOR_VERSION == 1 && MATERIALX_MINOR_VERSION == 38 && MATERIALX_BUILD_VERSION == 3
     mxContext.registerSourceCodeSearchPath(searchPath);
@@ -122,6 +144,7 @@ HdSt_GenMaterialXShader(
     for (const mx::FilePath &path : searchPath) {
         if (path.getBaseName() == "libraries") {
             libSearchPaths.append(path.getParentPath());
+            libSearchPaths.append(path);
         }
         else {
             libSearchPaths.append(path);
@@ -863,6 +886,7 @@ _GenerateMaterialXShader(
     HdMaterialNode2 const& terminalNode,
     SdfPath const& terminalNodePath,
     TfToken const& materialTagToken,
+    TfToken const& apiName,
     bool const bindlessTexturesEnabled)
 {
     // Load Standard Libraries/setup SearchPaths (for mxDoc and mxShaderGen)
@@ -901,7 +925,7 @@ _GenerateMaterialXShader(
     mxHdInfo.bindlessTexturesEnabled = bindlessTexturesEnabled;
 
     // Generate the glslfx source code from the mtlxDoc
-    return HdSt_GenMaterialXShader(mtlxDoc, searchPath, mxHdInfo);
+    return HdSt_GenMaterialXShader(mtlxDoc, searchPath, mxHdInfo, apiName.GetString());
 }
 
 void
@@ -927,6 +951,8 @@ HdSt_ApplyMaterialXFilter(
             resourceRegistry->GetHgi()->GetCapabilities()->IsSet(
                 HgiDeviceCapabilitiesBitsBindlessTextures);
 
+        const TfToken apiName = resourceRegistry->GetHgi()->GetAPIName();
+
         // If the MaterialNetwork has just a terminal node, utilize the
         // Resource Registry to cache the generated MaterialX glslfx Shader
         if (hdNetwork->nodes.size() == 1) {
@@ -942,7 +968,7 @@ HdSt_ApplyMaterialXFilter(
                 // Generate the MaterialX glslfx ShaderPtr
                 glslfxShader = _GenerateMaterialXShader(
                     hdNetwork, materialPath, terminalNode, terminalNodePath, 
-                    materialTagToken, bindlessTexturesEnabled);
+                    materialTagToken, apiName, bindlessTexturesEnabled);
 
                 // Store the mx::ShaderPtr 
                 glslfxInstance.SetValue(glslfxShader);
@@ -965,8 +991,8 @@ HdSt_ApplyMaterialXFilter(
         else {
             // Process the network and generate the MaterialX glslfx ShaderPtr
             glslfxShader = _GenerateMaterialXShader(
-                hdNetwork, materialPath, terminalNode, terminalNodePath, 
-                materialTagToken, bindlessTexturesEnabled);
+                hdNetwork, materialPath, terminalNode, terminalNodePath,
+                materialTagToken, apiName, bindlessTexturesEnabled);
 
             // Add material parameters from the glslfxShader
             _AddMaterialXParams(glslfxShader, materialParams);

pxr/imaging/hdSt/materialXFilter.h

@@ -66,7 +66,8 @@ void HdSt_ApplyMaterialXFilter(
 MaterialX::ShaderPtr HdSt_GenMaterialXShader(
     MaterialX::DocumentPtr const& mxDoc,
     MaterialX::FileSearchPath const& searchPath,
-    HdSt_MxShaderGenInfo const& mxHdInfo=HdSt_MxShaderGenInfo());
+    HdSt_MxShaderGenInfo const& mxHdInfo=HdSt_MxShaderGenInfo(),
+    std::string const& apiName="");
 
 PXR_NAMESPACE_CLOSE_SCOPE