Sorry for the very late reply Spike
vulkan requires precompiled spirv blobs instead of glsl. fte's glsl renderer does try to take advantage of an nvidia extension to use glsl directly, but it doesn't support any permutations, so its kinda only useful for 2d stuff, like post-processing effects.
Wow, thanks Spike, didn't know of Spir-V at all, start digging into!
Unfortunately I tried a very simple csqc postprocessing effect (add a vec4 col to GL_FragColor) but it doesn't take effect
I thought bloom+fxaa were working now, but I guess I screwed something up with barriers (I was a little lazy and just went with what worked for me rather than going through it in great detail, so it doesn't exactly surprise me if you get glitches).
Well, I made some errors. Bloom do works, but fxaa not. (At least bloom is safe!)
there's also some weird performance issues with vulkan, like 1920*1080 getting only half the framerate of d3d9, despite the vulkan renderer just clearing the screen with the d3d9 renderer drawing the entire world... but oh well... vulkan copes better with lower resolutions at least.
But, is it a peculiarity of Vulkan itself or is it regarding only FTEQW implementation?
Because in latter case, there's margin of improvements, in the first case, Vulkan will be very useless!