Mac platform support (intel and arm)

[moraaar]

What's new?

• Added Mac platform support to PhysX 5.1.
• New build preset mac64 added. It supports 64-bit x86_64 architecture with SSE2 SIMD instructions.
• New build preset mac-arm64 added. It supports 64-bit arm architecture with NEON SIMD instructions.
• Support for generating PhysX as either static or dynamic libraries.
• New Mac platform readme.

Out of Scope

The following points are considered out of scope, they can be added in the future:

• Support for PhysX Snippets.
• Support for Omniverse Visual Debugger (OmniPVD) .
• Support for other architectures: 32-bit x86

Known Errors/Limitations

• The name of the bin folder for mac-arm64 will appear as bin\mac.x86_64. To fix this nVidia has to modify the CMakeModules package it's downloaded from packman when building PhysX (Modify CMakeModules package Packman downloads to include Android, iOS and Mac platforms NVIDIA-Omniverse/PhysX#59). The file that needs to be modified is GetCompilerAndPlatform.cmake, modifying the mac lines of the if condition inside GetPlatformBinName function to this:

	ELSEIF(TARGET_BUILD_PLATFORM STREQUAL "mac")
		IF(${PX_OUTPUT_ARCH} STREQUAL "x86")
			SET(RETVAL "mac.x86_${LIBPATH_SUFFIX}")
		ELSEIF(${PX_OUTPUT_ARCH} STREQUAL "arm")
			SET(RETVAL "mac.arm64")
		ENDIF()

• Python package used by packman is based on x86_64 architecture and generates the error dyld[number]: missing symbol called when run on an arm-based Mac. To fix this nVidia has to add an ARM python package for mac into the packman scripts (Add to packman the arm-based version of python for Mac NVIDIA-Omniverse/PhysX#60). As a temporary solution, use your system's python adding the environment variable PM_PYTHON_EXT before building (for example by adding export PM_PYTHON_EXT="python3" into your .bash_profile file).
• PhysX Systems that require a CUDA capable GPU are not supported in Mac, for example particle system or cloth simulation.

Testing

• Built PhysX 5.1 successfully on mac64 in debug, checked, profile and release using PX_GENERATE_STATIC_LIBRARIES set to both true and false. The right output binaries were generated in bin/mac.x86_64
• Built PhysX 5.1 successfully on mac-arm64 in debug, checked, profile and release using PX_GENERATE_STATIC_LIBRARIES set to both true and false. The right output binaries were generated in bin/mac.arm64
• Built cmake install target successfully. It generated the correct output for Mac under install/mac64 and install/mac-arm64 folders, only including necessary headers for Mac.
• Runtime tested using Open 3D Engine (O3DE) with an early integration branch. The following video shows O3DE running PhysX 5.1 on mac64.
  https://user-images.githubusercontent.com/27999040/204763960-7fe2763e-c3b1-4c73-a6fb-ad3357ef02d3.mov

Signed-off-by: moraaar moraaar@amazon.com