I expected that Vulkan would at least be on par, 30%+ difference it too much for my taste. I don’t know where the bottleneck is. Just to place those tests here, since I posted as message to :
"So far, we have choosen a scene not too complex, with simple materials mostly (all green), FX 9370 3.6GHz and GTX 1080 not OC’ed
Conditions: texture sizes 2048, Epic settings, Full HD, dynamic lighting, main light with movement each second to simulate 1 hour = 36 seconds (time pass 100 x faster), minimum SM5 feature set, Vulkan for Desktop
test a) Deferred Render, DX12, SM5, 160 raymarch steps : 69 FPS
test b) Deferred Render, DX12, SM5, 384 raymarch steps : 51 FPS
test c) Forward Render, DX12, SM5, 160 raymarch steps: 84 FPS
test d) Forward Render, DX12, SM5, 384 raymarch steps: 58 FPS
test e) Deferred Render, Vulkan, SM5, 160 raymarch steps : 46 FPS
test f) Deferred Render, Vulkan, SM5, 384 raymarch steps : 35 FPS
test g) Forward Render, Vulkan, SM5, 160 raymarch steps: 57 FPS
test h) Forward Render, Vulkan, SM5, 384 raymarch steps: 41 FPS"
Just to complete as info, the material tested was a giant cube with two-sided material, so I am drawing inside and the camera picks a very small part of this mesh since it is inside it, this is how it looks like in a video at 15min:50sec (it is just too long, so check that the spot) : https://youtu.be/InBJKNQcU9M
The scene I was expecting to get in test “e” at least 80 FPS, but went from 69 to 46 which is 33% less… would be nice to stay the same…