[Feature Request] Support for HDR Output

[SaltyBet]

What should happen

Support for HDR Output.

Who would this benefit

Anyone gaming using:

• An HDR-capable display, like an HDR monitor or HDR TV.
• An HDR-capable mobile gaming device, like a Steam Deck OLED.

Platform (if relevant)

Windows

Games this would be useful in

All

Other emulators or software with a similar feature

• Dolphin.
• RetroArch.

Checklist

• Check the latest git build in case it's already implemented.
• Search for other requests of the same feature.

[anr2me]

Isn't just post-process shaders? like this PR dolphin-emu/dolphin#12003 and this dolphin-emu/dolphin#12603

[hrydgard]

Well, PSP games don't really output any real HDR information so just like in Dolphin, indeed it would be some functionality added to let post-shaders output HDR signal instead of just 0-255 at SRGB gamma.

But additional work is needed to switch to a swapchain (output) format with more than RGBA8888 precision. This is probably only doable with Vulkan/MoltenVK and maybe D3D11 (not sure).

So yeah, this is really a legitimate feature request for:

• Post shaders to be able to specify that their output is HDR
• Code to switch to a HDR swapchain if such a post shader is used.

Big problem: Android still doesn't support HDR swapchains! So we can only support PC/Mac/iOS/maybe Linux.