3 ms·

Will there be an OpenGL compatibility layer on top of Vulkan? Otherwise, GPU vendors will have to maintain OpenGL for backwards compatibility for a very long ti

by qznc 11y ago

Will there be an OpenGL compatibility layer on top of Vulkan? Otherwise, GPU vendors will have to maintain OpenGL for backwards compatibility for a very long time?

AshleysBrain 11y ago
I think this is an interesting point - in theory I guess it's possible that some kind of library or framework could implement OpenGL on top of Vulkan. It would be a bit like writing a graphics driver in user code, and it could have advantages: Vulkan should have more predictable performance, so OpenGL-on-Vulkan should have more predictable performance too compared to the black box driver with mystery performance pitfalls. It would be far easier to debug and profile for performance issues, and easy to gracefully fall back to normal OpenGL calls where Vulkan isn't supported (just forward the calls to the driver's OpenGL). Still, I'm not sure who would develop such a framework. It could be a new backend for ANGLE (the framework browsers use to implement OpenGL on top of Direct3D). It might also be too difficult - the whole point of Vulkan is to avoid GPU drivers having to have vast, complex, buggy and slow OpenGL compatibility layers, and OpenGL-on-Vulkan may end up just reimplementing the same thing with the same pitfalls.
lmm 11y ago
I suspect vendors will start implementing more and more of OpenGL in software (and indeed a lot of it's already in the driver) - cards will keep getting better, but there (hopefully) won't be new OpenGL-only software, so it will be ok if OpenGL doesn't unlock a card's full performance. Look at e.g. modern graphics cards' support for 8-bit textures, or MIDI synthesis on modern sound cards. Whether that will be in the form of an explicit OpenGL-on-Vulkan library, or just similar things within vendor driver implementations, I can't say. Graphics card drivers are already enormous and contain a lot of backward compatibility code.

by qznc 11y ago

Will there be an OpenGL compatibility layer on top of Vulkan? Otherwise, GPU vendors will have to maintain OpenGL for backwards compatibility for a very long time?

AshleysBrain 11y ago

I think this is an interesting point - in theory I guess it's possible that some kind of library or framework could implement OpenGL on top of Vulkan. It would be a bit like writing a graphics driver in user code, and it could have advantages: Vulkan should have more predictable performance, so OpenGL-on-Vulkan should have more predictable performance too compared to the black box driver with mystery performance pitfalls. It would be far easier to debug and profile for performance issues, and easy to gracefully fall back to normal OpenGL calls where Vulkan isn't supported (just forward the calls to the driver's OpenGL). Still, I'm not sure who would develop such a framework. It could be a new backend for ANGLE (the framework browsers use to implement OpenGL on top of Direct3D). It might also be too difficult - the whole point of Vulkan is to avoid GPU drivers having to have vast, complex, buggy and slow OpenGL compatibility layers, and OpenGL-on-Vulkan may end up just reimplementing the same thing with the same pitfalls.

lmm 11y ago

I suspect vendors will start implementing more and more of OpenGL in software (and indeed a lot of it's already in the driver) - cards will keep getting better, but there (hopefully) won't be new OpenGL-only software, so it will be ok if OpenGL doesn't unlock a card's full performance. Look at e.g. modern graphics cards' support for 8-bit textures, or MIDI synthesis on modern sound cards. Whether that will be in the form of an explicit OpenGL-on-Vulkan library, or just similar things within vendor driver implementations, I can't say. Graphics card drivers are already enormous and contain a lot of backward compatibility code.