This was cause by the change of some epsilon values for reflections.
This commit changes the planar reflection tracing to have correct
handling of parallel rays and discard any self intersection with normal
screen raytrace.
Accumulate error caused by the low amount of integration slices and
correct it for the low roughness surfaces.
This increases light leak but it is less distracting than dark fringe
everywhere.
The shader was not using the horizon texture and was trying to
trace the AO again.
Also the depth reconstruction was off because now using the maxzBuffer.
This happens when the normal is too much deformed to give valid
reflection even after ensure_valid_reflection.
Cycles seems to not handle this case either so we just discard the
rays.
Simple divide by 0 error. The input radius was assumed to be safe
but is not when the user can scale it arbitrarly.
This also move the division out of the loop.
We now reuse 9 hitpoints from the neighboorhood using a blue noise
sample distribution as mentionned in the reference presentation.
Reusing more rays does however make some area a bit more blury.
The resulting noise is quite lower compared to previous implementation
which was only reusing 4 hits.
This make sure the rays are generated randomly from a fullres
texel center.
This creates more noise but increase the convergence when doing
half res tracing.
This split is to make code easier to manage and rename the files to
`effect_reflection_*` to avoid confusion.
Also this cleans up a bit of the branching mess in the trace shader.
This makes the hit delta threshold dependant on the ray angle.
If the ray is more aligned with the view, its intersection
threshold gets bigger to avoid going through geometry.
This improves reflections and fix T86448 refraction issue.
We now have a new buffer to output reflection depth. This buffer is
only usefull for non planar SSR but we use it to tag the planar rays.
This also touch the raytrace algo for planars to avoid degenerate
lines on vert sharp reflections.
This changes the sampling routine to use the method described in
"A Simpler and Exact Sampling Routine for the GGXDistribution of Visible Normals"
by Eric Heitz.
http://jcgt.org/published/0007/04/01/slides.pdf
This avoids generating bad rays and thus improve noise level in screen-
space reflections / refraction.
This changes the hitBuffer to store `ReflectionDir * HitTime, invPdf`
just as the reference presentation.
This avoids issues when the hit refinement produce a coordinate that
does not land on the correct surface.
We now store the pdf in the same texture and store it inversed so we can
remove some ALU from the resolve shader.
This also rewrite the resolve shader to not be vectorized to improve
readability and scalability.
This just bypass the occlusion computation if there is no occlusion
data. This avoids weird looking occlusion due to the screen space
geometric normal reconstruction.
The sampling is now optimum with every samples being at least one pixel
appart. Also use a squared repartition to improve the sampling near the
center.
This also removes the thickness heuristic since it seems to remove
a lot of details and bias the AO too much.
This is a major rewrite that improves the screen space raytracing
a little bit.
This also decouple ray preparation from raytracing to be reuse in other
part of the code.
This changes a few things:
- Reflections have lower grazing angle failure
- Reflections have less self intersection issues
- Contact shadows are now fully opaque (faster)
Unrelated but some self intersection / incorrect bad rays are caused by
the ray reconstruction technique used by the SSR. This is not fixed by
this commit but I added a TODO.
This removes the need for per mipmap scalling factor and trilinear interpolation
issues. We pad the texture so that all mipmaps have pixels in the next mip.
This simplifies the downsampling shader too.
This also change the SSR radiance buffer as well in the same fashion.
The SSS shader in Eevee has the following drawbacks (elaborated in {T79933}):
1. Glowing
2. Ringing. On low SSS jittering it is rendered a bunch of sharp lines
3. Overall blurriness due to the nature of the effect
4. Shadows near occlusions as in T65849
5. Too much SSS near the edge and on highly-tilted surfaces
{F9438636}
{F9427302}
In the original shader code there was a depth correction factor, as far as I can understand for fixing light bleeding from one object to another. But it was scaled incorrectly. I modified its scale to depend on SSS scale*radius and made it independent from the scene scale. The scale parameter (`-4`) is chosen so that it makes tilted surfaces to have visually the same SSS radius as straight surfaces (surfaces with normal pointed directly to the camera).
This depth correction factor alone fixes all the problems except for ringing (pt. 2). Because of float-point precision errors and irradiance interpolation some samples near the border of an object might leak light, causing sparkly or dashed (because of aliasing) patterns around the highlights. Switching from `texture()` to `texelFetch()` fixes this problem and makes textures on renders visually sharper.
An alternative solution would be to detect object borders and somehow prevent samples from crossing it. This can be done by:
1. Adding an `object_id` texture. I think it requires much more code changing and makes the shader more complicated. Again, `object_id` is not interpolatable.
2. Watch gradient of depth and discard samples if the gradient is too big. This solution depends on scene scale and requires more texture lookups. Since SSS is usually a minor effect, it probably doesn't require that level of accuracy.
I haven't notice it in practice, but I assume it can make visible SSS radius slightly off (up to 0.5 px in screen space, which is negligible). It is completely mitigated with render sampling.
Reviewed By: Clément Foucault
Differential Revision: https://developer.blender.org/D9740
This is ported from Cycles and fixes issues with bump/normal mapping
giving weird reflections/lighting.
Fixes T81070 Specular light should be limited to normal pointing toward the camera
Fixes T78501 Normal mapping making specular artifact
The shadowing was computed on the light distance squared,
leaking to much light since it was integrating the extinction behind
the ligth itself.
Also bump the maximum shadow max step to the actual UI values. Otherwise
we get shadowing under evaluated because `dd` is too small.
Contact shadows needed correct `gl_FragCoord.z` but this is not
correctly set for fullscreen passes. Need to pass depth using a global
variable until we get rid of `cl_eval.tracing_depth`.
This adds an approximation of inverted AO by reversing the max horizon
search (becoming a min horizon). The horizons are correctly clamped in
the reverse direction to the shading and geometric normals.
The arc integration is untouched as it seems to be symetrical.
The limitation of this technique is that since it is still screen-space
AO you don't get other hidden surfaces occlusion. This is more
problematic in the case of inverted AO than for normal AO but it's
better than no support AO.
Support of distance parameter was easy thanks to recent AO refactor.
Fix regression with roughness not masking reflections when not using
Screen Space raytracing.
The trick was to only evaluate one planar per pixel, the one with
the most influence. This should not be too limiting since this is what
we do for SSR.
Also change evaluation order do not apply occlusion on planars probes.
- Fix noise/banding artifact on distant geometry.
- Fix overshadowing on un-occluded surfaces at grazing angle producing "fresnel"
like shadowing. Some of it still appears but this is caused to the low number
of horizons per pixel.
- Improve performance by using a fixed number of samples and fixing the
sampling area size. A better sampling pattern is planned to recover
the lost precision on large AO radius.
- Improved normal reconstruction for the AO pass.
- Improve Bent Normal reconstruction resulting in less faceted look on
smoothed geometry.
- Add Thickness heuristic to avoid overshadowing of thin objects.
Factor is currently hardcoded.
- Add bent normal support to Glossy reflections.
- Change Glossy occlusion to give less light leaks from lightprobes.
It can overshadow on smooth surface but this should be mitigated by
using SSR.
- Use Bent Normal for rough Glossy surfaces.
- Occlusion is now correctly evaluated for each BSDF. However this does make
everything slower. This is mitigated by the fact the search is a lot faster
than before.
This changes the roughness mapping to better utilize the mip chain resolution.
This improves glossy reflections with small roughness.
Lightcache version bumped because old data does not have the same roughness
mapping and cannot be used.
This modifies the principled BSDF and the Glass BSDF which now
have better fit to multiscatter GGX.
Code to generate the LUT have been updated and can run at runtime.
The refraction LUT has been changed to have the critical angle always
centered around one pixel so that interpolation can be mitigated.
Offline LUT data will be updated in another commit
This simplify the BTDF retreival removing the manual clean cut at
low roughness. This maximize the precision of the LUT by scalling
the sides by the critical angle.
I also touched the ior > 1.0 approximation to be smoother.
Also incluse some cleanup of bsdf_sampling.glsl
