Add support for MaterialX builds on iOS (#1435)

Thanks to @ikuznetcova for the contribution

.github/workflows/main.yml

@@ -83,6 +83,15 @@ jobs:
           python: 3.11
           test_shaders: ON
 
+        - name: iOS_Xcode_14_Python311
+          os: macos-13
+          compiler: xcode
+          compiler_version: "14.3"
+          python: None
+          cmake_config: -DMATERIALX_BUILD_IOS=ON -DMATERIALX_BUILD_PYTHON=OFF -DMATERIALX_BUILD_VIEWER=OFF -DMATERIALX_BUILD_GRAPH_EDITOR=OFF
+              -DCMAKE_OSX_SYSROOT=`xcrun --sdk iphoneos --show-sdk-path`
+              -DCMAKE_OSX_ARCHITECTURES=arm64
+
         - name: Windows_VS2019_Win32_Python37
           os: windows-2019
           architecture: x86

CMakeLists.txt

@@ -55,6 +55,27 @@ option(MATERIALX_WARNINGS_AS_ERRORS "Interpret all compiler warnings as errors."
 option(MATERIALX_DYNAMIC_ANALYSIS "Build MaterialX libraries with dynamic analysis on supporting platforms." OFF)
 option(MATERIALX_OSL_LEGACY_CLOSURES "Build OSL shader generation supporting the legacy OSL closures." ON)
 
+option(MATERIALX_BUILD_IOS "Build MaterialX for iOS." OFF)
+if (MATERIALX_BUILD_IOS)
+    set(CMAKE_SYSTEM_NAME iOS)
+    add_definitions(-DTARGET_OS_IOS=1)
+    set(MATERIALX_BUILD_PYTHON        OFF)
+    set(MATERIALX_BUILD_VIEWER        OFF)
+    set(MATERIALX_BUILD_GRAPH_EDITOR  OFF)
+    set(MATERIALX_BUILD_GEN_GLSL      OFF)
+    set(MATERIALX_BUILD_GEN_OSL       OFF)
+    set(MATERIALX_BUILD_GEN_GLSL      OFF)
+    set(MATERIALX_BUILD_GEN_MDL       OFF)
+    set(MATERIALX_BUILD_OIIO          OFF)
+    set(MATERIALX_PYTHON_LTO          OFF)
+    set(MATERIALX_INSTALL_PYTHON      OFF)
+    set(MATERIALX_DYNAMIC_ANALYSIS    OFF)
+    set(MATERIALX_DYNAMIC_ANALYSIS    OFF)
+    set(MATERIALX_OSL_LEGACY_CLOSURES OFF)
+    set(MATERIALX_BUILD_TESTS         OFF)
+    set(MATERIALX_TEST_RENDER         OFF)
+endif()
+
 set(MATERIALX_PYTHON_VERSION "" CACHE STRING
     "Python version to be used in building the MaterialX Python package (e.g. '3.9').")
 set(MATERIALX_PYTHON_EXECUTABLE "" CACHE FILEPATH
@@ -134,6 +155,7 @@ mark_as_advanced(MATERIALX_INSTALL_LIB_PATH)
 mark_as_advanced(MATERIALX_INSTALL_STDLIB_PATH)
 mark_as_advanced(MATERIALX_BUILD_JS)
 mark_as_advanced(MATERIALX_EMSDK_PATH)
+mark_as_advanced(MATERIALX_BUILD_IOS)
 if (MATERIALX_BUILD_GEN_MDL)
     mark_as_advanced(MATERIALX_MDLC_EXECUTABLE)
     mark_as_advanced(MATERIALX_MDL_RENDER_EXECUTABLE)

source/MaterialXRenderHw/CMakeLists.txt

@@ -4,7 +4,9 @@ file(GLOB materialx_source "${CMAKE_CURRENT_SOURCE_DIR}/*.cpp")
 file(GLOB materialx_headers "${CMAKE_CURRENT_SOURCE_DIR}/*.h*")
 
 if(APPLE)
+if (NOT MATERIALX_BUILD_IOS)
   find_library(COCOA_FRAMEWORK Cocoa)
+endif()
   file(GLOB materialx_source_oc "${CMAKE_CURRENT_SOURCE_DIR}/*.m")
   message("Objective C files: " ${materialx_source_oc})
   set_source_files_properties(${materialx_source_oc} PROPERTIES
@@ -26,6 +28,12 @@ add_library(${MATERIALX_MODULE_NAME} ${materialx_source} ${materialx_headers})
 
 add_definitions(-DMATERIALX_RENDERHW_EXPORTS)
 
+if(APPLE AND NOT MATERIALX_BUILD_IOS)
+set(CMAKE_DL_LIBS
+${CMAKE_DL_LIBS}
+"-framework Cocoa")
+endif()
+
 # Create version resource
 if(MATERIALX_BUILD_SHARED_LIBS AND MSVC)
     configure_file(${CMAKE_SOURCE_DIR}/cmake/modules/MaterialXVersion.rc.in ${CMAKE_CURRENT_BINARY_DIR}/version.rc)
@@ -43,7 +51,6 @@ elseif(APPLE)
         MaterialXRender
         ${CMAKE_DL_LIBS}
         "-framework Foundation"
-        "-framework Cocoa"
         "-framework Metal")
 elseif(UNIX)
     target_link_libraries(

source/MaterialXRenderHw/SimpleWindowIOS.cpp

@@ -0,0 +1,40 @@
+//
+// Copyright Contributors to the MaterialX Project
+// SPDX-License-Identifier: Apache-2.0
+//
+
+#if defined(__APPLE__)
+
+#ifdef TARGET_OS_IOS
+
+#include <MaterialXRenderHw/SimpleWindow.h>
+
+MATERIALX_NAMESPACE_BEGIN
+
+SimpleWindow::SimpleWindow() :
+    _width(0),
+    _height(0)
+{
+    // Give a unique identifier to this window.
+    static unsigned int windowCount = 1;
+    _id = windowCount;
+    windowCount++;
+}
+
+bool SimpleWindow::initialize(const char* title,
+                              unsigned int width, unsigned int height,
+                              void* /*applicationShell*/)
+{
+    _windowWrapper = WindowWrapper::create(nullptr);
+    return true;
+}
+
+SimpleWindow::~SimpleWindow()
+{
+}
+
+MATERIALX_NAMESPACE_END
+
+#endif
+
+#endif

source/MaterialXRenderHw/SimpleWindowMac.cpp

@@ -5,6 +5,8 @@
 
 #if defined(__APPLE__)
 
+#ifndef TARGET_OS_IOS
+
 #include <MaterialXRenderHw/SimpleWindow.h>
 #include <MaterialXRenderHw/WindowCocoaWrappers.h>
 
@@ -42,3 +44,5 @@ SimpleWindow::~SimpleWindow()
 MATERIALX_NAMESPACE_END
 
 #endif
+
+#endif

source/MaterialXRenderHw/WindowCocoaWrappers.m

@@ -5,6 +5,8 @@
 
 #if defined (__APPLE__)
 
+#ifndef TARGET_OS_IOS
+
 #import <Cocoa/Cocoa.h>
 #import <AppKit/NSApplication.h>
 #import <MaterialXRenderHw/WindowCocoaWrappers.h>
@@ -72,3 +74,5 @@ void NSUtilDisposeWindow(void* pWindow)
 }
 
 #endif
+
+#endif

source/MaterialXRenderHw/WindowWrapper.cpp

@@ -84,8 +84,12 @@ WindowWrapper::WindowWrapper(ExternalWindowHandle externalHandle,
                              DisplayHandle display)
 {
     _externalHandle = externalHandle;
+#ifndef TARGET_OS_IOS
     // Cache a pointer to the window.
     _internalHandle = NSUtilGetView(externalHandle);
+#else
+    _internalHandle = nullptr;
+#endif
 }
 
 WindowWrapper::~WindowWrapper()

source/MaterialXRenderMsl/CMakeLists.txt

@@ -11,8 +11,10 @@ if(POLICY CMP0072)
 endif()
 
 if(APPLE)
+if(NOT MATERIALX_BUILD_IOS)
     find_library(COCOA_FRAMEWORK Cocoa)
     find_package(OpenGL REQUIRED)
+endif()
     file(GLOB_RECURSE materialx_source_oc "${CMAKE_CURRENT_SOURCE_DIR}/*.m")
     message("Objective C files: " ${materialx_source_oc})
     set_source_files_properties(${materialx_source_oc} PROPERTIES
@@ -44,6 +46,12 @@ set(COMMON_LIBRARIES
     MaterialXRenderHw
     MaterialXGenMsl
     ${CMAKE_DL_LIBS})
+
+if(APPLE AND NOT MATERIALX_BUILD_IOS)
+set(COMMON_LIBRARIES
+    ${COMMON_LIBRARIES}
+    "-framework Cocoa")
+endif()
 
 if(MSVC)
     target_link_libraries(
@@ -56,7 +64,6 @@ elseif(APPLE)
         ${COMMON_LIBRARIES}
         ${OPENGL_LIBRARIES}
         "-framework Foundation"
-        "-framework Cocoa"
         "-framework Metal")
 elseif(UNIX)
     target_link_libraries(