OpenGL ES is deprecated on iOS

[bio1712]

All LÖVE should use Metal instead of OpenGL ES.
Apple could drop OpenGL ES support soon.

"Games and graphics-intensive apps that previously used OpenGL ES should now adopt Metal."

[slime73]

I've already started work on a Metal backend for love, however it's still in its early stages: slime73/love-experiments@12.0-development...slime73:metal

Whether that ends up in 12.0 or a new 11.x release depends on whether Apple removes OpenGL ES from its SDKs this year or not.

[slime73]

Whether that ends up in 12.0 or a new 11.x release depends on whether Apple removes OpenGL ES from its SDKs this year or not.

Apple will be continuing support for OpenGL / OpenGL ES in their new macOS and iOS releases, according to their new documentation. So if a Metal backend is completed, it will be for 12.0 rather than 11.x.

[slime73]

I've merged my metal branch into the 12.0-development branch (see #1761). But the OpenGL renderer has priority over the metal renderer by default for now, because there are still some things to resolve and improve with the metal backend (edit: it's in good enough shape these days that it has priority over OpenGL):

• Figure out a workaround or wait for an OS-side fix for discrete GPUs not fully activating (https://developer.apple.com/forums/thread/675411).
• Test and fix the Metal backend on iOS.
• Fix font texture compatibility on older systems.
• Fix clamp_one blend mode potentially crashing instead of erroring on older systems.
• Profile and investigate Buffer update performance.
• Test and fix texel buffers when they're sent to shaders.
• Clean up shader creation/reflection code.
• Fix triangle fan meshes by emulating the draw mode via an internal index buffer.
• Fix render pipeline creation when love's automatic depth/stencil settings are used in setCanvas.
• Fix color masks/stencil state to match the OpenGL backend, when stenciling is used.
• Decide whether to fall back to better supported depth/stencil formats if an unsupported 16 or 24 bit format is requested.
• Make sure pixel format support tables are correct.
• Fix shaders having stale sampler state if a Texture's sampler changes after it has been used with that shader.
• Test and fix texture MSAA.
• Fix textures not being initialized to transparent black in certain situations.
• Fix Texture:generateMipmaps to either error or work correctly when the format isn't filterable.
• Profile various scenarios to make sure there aren't unexpected performance issues.

The Metal backend currently requires macOS 10.15+ or iOS 13.0+.

[slime73]

There's one major known bug but it has a separate tracked issue (#1975), so I'll close this as solved now.