Cycles: enable Metal GPU rendering

This adds the remaining bits to enable Metal on macOS. There are still
performance optimizations and other improvements planned, but it should
now be ready for early testing.

This is currently only enabled on in Arm builds for M1 GPUs. It is not
yet working on AMD or Intel GPUs.

Ref T92212

Differential Revision: https://developer.blender.org/D13503

CMakeLists.txt

@@ -463,6 +463,11 @@ if(NOT APPLE)
   mark_as_advanced(CYCLES_HIP_BINARIES_ARCH)
 endif()
 
+# Apple Metal
+if(APPLE)
+  option(WITH_CYCLES_DEVICE_METAL       "Enable Cycles Apple Metal compute support" ON)
+endif()
+
 # Draw Manager
 option(WITH_DRAW_DEBUG "Add extra debug capabilities to Draw Manager" OFF)
 mark_as_advanced(WITH_DRAW_DEBUG)

build_files/cmake/config/blender_release.cmake

@@ -61,6 +61,7 @@ set(WITH_MEM_JEMALLOC          ON  CACHE BOOL "" FORCE)
 # platform dependent options
 if(APPLE)
   set(WITH_COREAUDIO           ON  CACHE BOOL "" FORCE)
+  set(WITH_CYCLES_DEVICE_METAL ON  CACHE BOOL "" FORCE)
 endif()
 if(NOT WIN32)
   set(WITH_JACK                ON  CACHE BOOL "" FORCE)

intern/cycles/cmake/external_libs.cmake

@@ -556,12 +556,17 @@ endif()
 ###########################################################################
 
 if(WITH_CYCLES_DEVICE_METAL)
-  FIND_LIBRARY(METAL_LIBRARY Metal)
+  find_library(METAL_LIBRARY Metal)
-  if (METAL_LIBRARY)
+
-    message(STATUS "Found Metal: ${METAL_LIBRARY}")
+  # This file was added in the 12.0 SDK, use it as a way to detect the version.
-  else()
+  if (METAL_LIBRARY AND NOT EXISTS "${METAL_LIBRARY}/Headers/MTLFunctionStitching.h")
+    message(STATUS "Metal version too old, must be SDK 12.0 or newer, disabling WITH_CYCLES_DEVICE_METAL")
+    set(WITH_CYCLES_DEVICE_METAL OFF)
+  elseif (NOT METAL_LIBRARY)
     message(STATUS "Metal not found, disabling WITH_CYCLES_DEVICE_METAL")
     set(WITH_CYCLES_DEVICE_METAL OFF)
+  else()
+    message(STATUS "Found Metal: ${METAL_LIBRARY}")
   endif()
 endif()
 

release/scripts/startup/bl_ui/space_userpref.py

@@ -596,9 +596,11 @@ class USERPREF_PT_system_cycles_devices(SystemPanel, CenterAlignMixIn, Panel):
 
     @classmethod
     def poll(cls, _context):
-        # No GPU rendering on macOS currently.
+        # No GPU rendering on macOS x86_64 currently.
+        import platform
         import sys
-        return bpy.app.build_options.cycles and sys.platform != "darwin"
+        return bpy.app.build_options.cycles and \
+               (sys.platform != "darwin" or platform.machine() == "arm64")
 
     def draw_centered(self, context, layout):
         prefs = context.preferences