Fake SSGI in Eevee

@Piotr_Adamowicz
I have to disagree with the take on screenspace effects. I’m speaking more generally and not specifically on this threads topic. Yeah, you shoudn’t use it as a main source of GI for example, but they still provide per pixel quality effects for a small performance cost. Biggest performance & quality boost DXR implementation got in Battlefield V was a patch adding SSR back on top of ray traced reflections for cases where it produced correct results and details that coudn’t be represented in ray traced reflections. The Unreal 5 GI solution uses screen space for the smallest details in combination with other techniques for things that are out of screen space. Same way SSGI in Unreal 4 is supposed to be used with lighmaps or with other lower fidelity GI solutions. Just raytracing everything, because now we can, seems like a naive approach. For the record I don’t think this should be in master, but a native SSGI combined with some other realtime GI solution should. Unless the cost of ray tracing drops dramatically.

@Metin_Seven
With relativley low intensity HDRI:



(ground material uses multiple BSDFs with vertex color blending, so a big chunck of it has no SSR. Nice example why you need to blend with texures and treat shaders like output nodes in Eevee).

Lower intensity and higher diffuse GI roughness seems to give okay results in the small amount of cases I’ve currently tested. I’m still looking into how it interacts with irradiance volumes (fine in small number of test cases) and cubemaps (broken) to see if I can quickly improve it before I release it. I’m currently thinking putting it up on gumroad for free / pay what you want.

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