This brings some data structure changes.
Shared shadow data are stored in ShadowData (in glsl) (aka EEVEE_Shadow in C).
This structure contains the array indices of the first shadow element of this shadow "object".
It also contains how many shadow to evaluate (to be used for Multiple shadow maps).
The filtering is noisy and needs improvement.
- Use only one 2d texture array to store all shadowmaps.
- Allow to change shadow maps resolution.
- Do not output radial distance when rendering shadowmaps. This will allow fast rendering of shadowmaps when we will drop the use of geometry shaders.
This means we have less overall noise for rendered image.
SSR, AO, and Refraction are affected by this change.
SSR still exhibit artifacts because the reconstruction pattern needs to change every frame (TODO).
This includes big improvement:
- The horizon search is decoupled from the BSDF evaluation. This means using multiple BSDF nodes have a much lower impact when enbaling AO.
- The horizon search is optimized by splitting the search into 4 corners searching similar directions to help which GPU cache coherence.
- The AO options are now uniforms and do not trigger shader recompilation (aka. freeze UI).
- Include a quality slider similar to the SSR one.
- Add a switch for disabling bounce light approximation.
- Fix problem with Bent Normals when occlusion get very dark.
- Add a denoise option to that takes the neighbors pixel values via glsl derivatives. This reduces noise but exhibit 2x2 blocky artifacts.
The downside : Separating the horizon search uses more memory (~3MB for each samples on HD viewport). We could lower the bit depth to 4bit per horizon but it produce noticeable banding (might be fixed with some dithering).
This fix a bug when occluder are on the edge of the screen and occludes more than they should.
Grouped the texture fetches together and clamp the ray at the border of the screen.
Also add a few util functions.
Theses Materials are rendered after the SSR pass.
The only difference with previous method is that they have a depth prepass (less overdraw) and are not sorted.
For the moment the only way to enable this is to:
- enable Screen Space REFLECTIONS.
- enable Screen Space Refraction in the SSR parameters.
- enable Screen Space Refraction in the material tab.
We generate a 3D lut to precompute the btdf intensity.
I decided to use a 64*64*16 (N dot V, ior, roughness) because the btdf varies less with roughness than with IOR.
We also remap the ior to better use the space in the LUT.
This add the possibility to use planar probe informations to create SSR.
This has 2 advantages:
- Tracing is less expensive since the hit is found much quicker.
- We have much less artifact due to missing information.
There is still area for improvement.
Output in 2 buffers Normals, Specular Color and roughness.
This way we can raytrace in a defered fashion and blend the exact contribution of the specular lobe on top of the opaque pass.
Hashed Alpha transparency offers a noisy output but has the benefit of being correctly ordered. Noise can be attenuated with Multisampling / AntiAliasing.
Read from the GPUMaterial to find custom-data layers used for drawing.
This resolves problem where having UV's would always calculate tangents
causing noticeable slow down compared to 2.7x.
The problem was that the depth prepass was using the clip plane but not the shading pass.
During the clipping stage, the triangle is converted to a quad clipped to the given clip plane.
But this introduce subtle changes in the depth when this new geometry is rasterized. Since the shading pass was using an EQUAL depth test, the depth values from the shading pass were not always equal to the depth prepass.
Enabling clipping in the shading vertex shader has a too small impact to require a dedicated shader.
Implement GTAO (Ground Truth Ambient Occlusion) which is a special case of Horizon Based Ambient Occlusion that is more physically accurate.
Also add a bent normal option to sample indirect irradiance (diffuse lighting) with the least occluded direction.
- Unify variations between default shaders and material shader.
- Only create default shader passes if needed.
Downside is that we have a big array of passes and shading grp in the vedata ... And it will double in size each time a new variation flag is added.
