Try runnin MSL renders in CI.

Author: kwokcb

.github/workflows/main.yml

@@ -204,7 +204,13 @@ jobs:
             EXTENDED_BUILD_CONFIG="$EXTENDED_BUILD_CONFIG -DMATERIALX_MDL_SDK_DIR=C:/vcpkg/installed/x64-windows"
           fi
         fi
-        cmake -S . -B build -DMATERIALX_BUILD_PYTHON=ON -DMATERIALX_BUILD_VIEWER=ON -DMATERIALX_BUILD_GRAPH_EDITOR=ON -DMATERIALX_BUILD_TESTS=ON -DMATERIALX_TEST_RENDER=OFF -DMATERIALX_WARNINGS_AS_ERRORS=ON $EXTENDED_BUILD_CONFIG ${{matrix.cmake_config}}
+        TEST_RENDER_CONFIG="-DMATERIALX_TEST_RENDER=OFF"
+        if [ "${{ matrix.test_render }}" == "ON" ]; then
+          if [ "${{ runner.os }}" == "macOS" ]; then
+            TEST_RENDER_CONFIG="$TEST_RENDER_CONFIG -DMATERIALX_TEST_RENDER=ON -DMATERIALX_RENDER_MSL_ONLY=ON"
+          fi
+        fi
+        cmake -S . -B build -DMATERIALX_BUILD_PYTHON=ON -DMATERIALX_BUILD_VIEWER=ON -DMATERIALX_BUILD_GRAPH_EDITOR=ON -DMATERIALX_BUILD_TESTS=ON -DMATERIALX_WARNINGS_AS_ERRORS=ON $TEST_RENDER_CONFIG $EXTENDED_BUILD_CONFIG ${{matrix.cmake_config}}
 
     - name: CMake Build
       run: cmake --build build --target install --config Release --parallel 2
@@ -297,9 +303,8 @@ jobs:
         ../installed/bin/MaterialXView --material usd_preview_surface_carpaint.mtlx --mesh ../../resources/Geometry/sphere.obj --screenWidth 128 --screenHeight 128 --cameraZoom 1.4 --shadowMap false --captureFilename Viewer_CarpaintTranslated.png
       working-directory: build/render
 
-    - name: Render Application Tests
-      if: matrix.test_render == 'ON' 
-      # && runner.os == 'Linux'
+    - name: Render Application Tests (GraphEditor - Linux only)
+      if: matrix.test_render == 'ON' && runner.os == 'Linux'
       run: |
         ../installed/bin/MaterialXGraphEditor --material ../../resources/Materials/Examples/StandardSurface/standard_surface_marble_solid.mtlx --viewWidth 128 --viewHeight 128 --captureFilename GraphEditor_MarbleSolid.png
       working-directory: build/render

CMakeLists.txt

@@ -45,6 +45,7 @@ option(MATERIALX_BUILD_GEN_MSL "Build the MSL shader generator back-end." ON)
 option(MATERIALX_BUILD_GEN_SLANG "Build the Slang shader generator back-end." ON)
 option(MATERIALX_BUILD_RENDER "Build the MaterialX Render modules." ON)
 option(MATERIALX_BUILD_RENDER_PLATFORMS "Build platform-specific render modules for each shader generator." ON)
+option(MATERIALX_RENDER_MSL_ONLY "On macOS, render with Metal Shading Language only (disables GLSL rendering)." OFF)
 option(MATERIALX_BUILD_OIIO "Build OpenImageIO support for MaterialXRender." OFF)
 option(MATERIALX_BUILD_OCIO "Build OpenColorIO support for shader generators." OFF)
 option(MATERIALX_BUILD_TESTS "Build unit tests." OFF)
@@ -112,6 +113,17 @@ if (MATERIALX_BUILD_JS)
     set(MATERIALX_BUILD_TESTS OFF)
 endif()
 
+# Validate MSL-only rendering option
+if(MATERIALX_RENDER_MSL_ONLY)
+    if(NOT APPLE)
+        message(FATAL_ERROR "MATERIALX_RENDER_MSL_ONLY can only be enabled on Apple platforms")
+    endif()
+    if(NOT MATERIALX_BUILD_GEN_MSL)
+        message(FATAL_ERROR "MATERIALX_RENDER_MSL_ONLY requires MATERIALX_BUILD_GEN_MSL to be enabled")
+    endif()
+    message(STATUS "MSL-only rendering mode enabled - GLSL rendering will be disabled")
+endif()
+
 # All hardware shading languages currently depend on the GLSL shader generator.
 if(MATERIALX_BUILD_GEN_MSL)
     set(MATERIALX_BUILD_GEN_GLSL ON)
@@ -178,6 +190,7 @@ mark_as_advanced(MATERIALX_BUILD_GEN_MSL)
 mark_as_advanced(MATERIALX_BUILD_OSOS)
 mark_as_advanced(MATERIALX_BUILD_RENDER)
 mark_as_advanced(MATERIALX_BUILD_RENDER_PLATFORMS)
+mark_as_advanced(MATERIALX_RENDER_MSL_ONLY)
 mark_as_advanced(MATERIALX_BUILD_OIIO)
 mark_as_advanced(MATERIALX_BUILD_OCIO)
 mark_as_advanced(MATERIALX_BUILD_BENCHMARK_TESTS)
@@ -502,8 +515,11 @@ if(MATERIALX_BUILD_RENDER)
     if(MATERIALX_BUILD_RENDER_PLATFORMS)
         set(MATERIALX_BUILD_RENDER_HW OFF)
         if(MATERIALX_BUILD_GEN_GLSL AND NOT MATERIALX_BUILD_APPLE_EMBEDDED)
-            set(MATERIALX_BUILD_RENDER_HW ON)
-            add_subdirectory(source/MaterialXRenderGlsl)
+            # Skip GLSL rendering on macOS if MSL-only mode is enabled
+            if(NOT (APPLE AND MATERIALX_RENDER_MSL_ONLY))
+                set(MATERIALX_BUILD_RENDER_HW ON)
+                add_subdirectory(source/MaterialXRenderGlsl)
+            endif()
         endif()
         if(MATERIALX_BUILD_GEN_MSL AND APPLE)
             set(MATERIALX_BUILD_RENDER_HW ON)
@@ -523,7 +539,12 @@ if(MATERIALX_BUILD_RENDER)
         add_subdirectory(source/MaterialXView)
     endif()
     if(MATERIALX_BUILD_GRAPH_EDITOR)
-        add_subdirectory(source/MaterialXGraphEditor)
+        # Graph Editor currently requires GLSL rendering
+        if(APPLE AND MATERIALX_RENDER_MSL_ONLY)
+            message(WARNING "MaterialXGraphEditor requires GLSL rendering and will not be built when MATERIALX_RENDER_MSL_ONLY is enabled on macOS")
+        else()
+            add_subdirectory(source/MaterialXGraphEditor)
+        endif()
     endif()
     if(MATERIALX_INSTALL_RESOURCES AND NOT SKBUILD)
         add_subdirectory(resources)

source/MaterialXGraphEditor/Main.cpp

@@ -171,11 +171,6 @@ int main(int argc, char* const argv[])
     if (!captureFilename.empty())
     {
         glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
-#if defined(__APPLE__)
-        // On macOS, when running headless we need to allow fallback to software rendering
-        // to avoid "Failed to find a suitable pixel format" errors in CI environments
-        glfwWindowHint(GLFW_COCOA_RETINA_FRAMEBUFFER, GLFW_FALSE);
-#endif
     }
 
     // Create window with graphics context

source/MaterialXView/CMakeLists.txt

@@ -11,7 +11,12 @@ if(APPLE)
       set(USE_OPENGL_BACKEND_ON_APPLE_PLATFORM ON)
     endif()
 
-    if(USE_OPENGL_BACKEND_ON_APPLE_PLATFORM)
+    # Force Metal backend if MSL-only rendering is enabled
+    if(MATERIALX_RENDER_MSL_ONLY)
+        set(USE_OPENGL_BACKEND_ON_APPLE_PLATFORM OFF)
+        set(NANOGUI_PREFERRED_BACKEND Metal)
+        set(MATERIALXVIEW_RENDER_BACKEND_DEFINITIONS "-DMATERIALXVIEW_METAL_BACKEND=1")
+    elseif(USE_OPENGL_BACKEND_ON_APPLE_PLATFORM)
         set(NANOGUI_PREFERRED_BACKEND OpenGL)
 	set(MATERIALXVIEW_RENDER_BACKEND_DEFINITIONS "-DMATERIALXVIEW_OPENGL_BACKEND=1")
     else()