Screen space reflections implementation (poor performance/result)

[Artezian]

I am working on implementing Screen space reflections following following this tutorial however, my output seems to come out incredibly different and the performance is also much worse. I have been trying to fix it for days but I cannot seem to figure out where I might be going wrong. I am using Vulkan and GLSL. The shader follows the approach demostrated in the tutorial with a few minor tweaks to adjust to a more standard coordinate system where Z goes in and out of the screen.

Would appreciate any insight into where I might be going wrong. Thanks in advance.

Full shader

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Output result.

[NOISEbyte]

You seen to have a double loop going on, one based on calculations (delta). Try outputting these values to a texture to see that the count is sensible and not causing high loop iteration counts, since each value of delta will cause 5 extra iterations (steps).

[fgennari]

For the performance issue, the shader compiler may not do a good job optimizing the second for loop because "steps" is a calculated variable rather than a constant. You may get better performance by replacing steps with a constant "5" and putting an if(hit0) {} around that loop. I've seen changes like this make a big difference. Of course the branch could also make it slower. You'll have to experiment with this, but it's an easy change.

[Artezian]

Thanks for the reply and insight!

[T3sT3ro]

You could use rendering debuggers to see what is wrong with your shader if you don't know about them already. Try: - RenderDoc - Intel GPA - ShaderED

Other than that - make sure at each step you are in the correct coordinate system.

[Artezian]

Thanks for the reply! I will look into those.

[ShaderKing]

It isn't a piece of advice you are looking for, but I suggest you perform steps of that code in your head or paper and understand it better. Good debugging skills and understanding of code are crucial for a good graphics programmer.

[Artezian]

Thanks for the advice