[ignore this: personal post as bookmarked reference]
Since the real discussion has moved I figure I’d write a final reply as a collection of options for anyone who wants to write OpenGL or use a game/app that renders using OpenGL and run it on a platform that only has Vulkan/Metal/DX HAL drivers.
Projects
Cocos2D w/new Backend (zhangxm / cocos team writing native Metal backend)
** major benefit is native perf (depends on date completed, rest should be usable today w/unknown perf hit)
Progress of new backend API .
ANGLE - OpenGL ES 2.0 -> GL 4 (desktop), WebGL, DX9, DX11, Vulkan, ES 3.1, and “soon” Metal
https://chromium.googlesource.com/angle/angle .
Zink - OpenGL -> Vulkan
Uses MESA software rendering lib/framework and acts as Proxy to Vulkan rendering.
https://www.kusma.xyz/blog/2018/10/31/introducing-zink.html .
MoltenGL - OpenGL -> Metal (unknown pricing for license(s))
https://moltengl.com/ .
MoltenVK - Vulkan -> Metal - Open Sourced by Khronos Group
** usable to use as MacOS backend for Zink or ANGLE(vulkan) with unknown perf hit
https://github.com/KhronosGroup/MoltenVK .
Others Rendering/Game Engines
https://github.com/google/filament .
Self link back to reply listing shader porting reference:
Graphics backend for opengl and metal .