Now hashed alpha materials are stable when moving the camera/not using TAA.
It also converge to a noise free image when using TAA. No more numerical imprecision.
There still can be situations with multiple overlapping transparent surfaces that can lead to residual noise.
Using GL_RG16I texture for the hit coordinates increase tremendously the precision of the hit.
The sign of the integer is used to 2 flags (has_hit and is_planar).
We do not store the depth and retrieve it from the depth buffer (increasing bandwith by +8bit/px).
The PDF is stored into another GL_R16F texture.
We remove the raycount for simplicity and to reduce compilation time (less branching in refraction shader).
This augment the existing irradiance grid with a new visibility precomputation.
We store a small shadowmap for each grid sample so that light does not leak through walls and such.
The visibility parameter are similar to the one used by the Variance Shadow Map for point lights.
Technical details:
We store the visibility in the same texture (array) as the irradiance itself (in order to reduce the number of sampler).
But the irradiance and the visibility are not the same data so we must encode them in order to use the same texture format.
We use RGBA8 normalized texture and encode irradiance as RGBE (shared exponent).
Using RGBE encoding instead of R11_G11_B10 may lead to some lighting changes, but quality seems to be nearly the same in my test cases.
Using full RGBA16/32F maybe a future option but that will require much more memory and reduce the perf significantly.
Visibility moments (VSM) are encoded as 16bits fixed point precision using a special range. This seems to retain enough precision for the needs.
Also interpolation does not seems to be big problem (even though it's incorrect).
Previously the lighting of SSS material was not present in reflection probe or irradiance grid.
This does not compute the SSS correctly but at least output the corresponding irradiance power to the correct output.
This option prevent from automatically blurring the albedo color applied to the SSS.
While this is great for preserving details it can bleed more light onto the nearby objects since the blurring will be done on pure "white" irradiance.
This issue is to be tackled in a separate commit.
This cleanup removes the need of gigantic code duplication for each closure.
This also make some preformance improvement since it removes some branches and duplicated loops.
It also fix some mismatch (between cycles and eevee) with the principled shader.
The RenderResult struct still has a listbase of RenderLayer, but that's ok
since this is strictly for rendering.
* Subversion bump (to 2.80.2)
* DNA low level doversion (renames) - only for .blend created since 2.80 started
Note: We can't use DNA_struct_elem_find or get file version in init_structDNA,
so we are manually iterating over the array of the SDNA elements instead.
Note 2: This doversion change with renames can be reverted in a few months. But
so far it's required for 2.8 files created between October 2016 and now.
Reviewers: campbellbarton, sergey
Differential Revision: https://developer.blender.org/D2927
This adds the possibility to simulate things like red ears with strong backlight or material with high scattering distances.
To enable it you need to turn on the "Subsurface Translucency" option in the "Options" tab of the Material Panel (and of course to have "regular" SSS enabled in both render settings and material options).
Since the effect is adding another overhead I prefer to make it optional. But this is open to discussion.
Be aware that the effect only works for direct lights (so no indirect/world lighting) that have shadowmaps, and is affected by the "softness" of the shadowmap and resolution.
Technical notes:
This is inspired by http://www.iryoku.com/translucency/ but goes a bit beyond that.
We do not use a sum of gaussian to apply in regards to the object thickness but we precompute a 1D kernel texture.
This texture stores the light transmited to a point at the back of an infinite slab of material of variying thickness.
We make the assumption that the slab is perpendicular to the light so that no fresnel or diffusion term is taken into account.
The light is considered constant.
If the setup is similar to the one assume during the profile baking, the realtime render matches cycles reference.
Due to these assumptions the computed transmitted light is in most cases too bright for curvy objects.
Finally we jitter the shadow map sample per pixel so we can simulate dispersion inside the medium.
Radius of the dispersion is in world space and derived by from the "soft" shadowmap parameter.
Idea for this come from this presentation http://www.iryoku.com/stare-into-the-future (slide 164).
Samples : pretty self explanatory.
Jitter Threshold : Reduce cache misses and improve performance (greatly) by lowering this value. This settings let user decide how many samples should be jittered (rotated) to reduce banding artifacts.
How to use:
- Enable subsurface scattering in the render options.
- Add Subsurface BSDF to your shader.
- Check "Screen Space Subsurface Scattering" in the material panel options.
This initial implementation has a few limitations:
- only supports gaussian SSS.
- Does not support principled shader.
- The radius parameters is baked down to a number of samples and then put into an UBO. This means the radius input socket cannot be used. You need to tweak the default vector directly.
- The "texture blur" is considered as always set to 1
This also:
- make sure to only compile the shader needed by the active effects.
- same thing for the shading groups.
- disable TAA if motion blur is active (avoid infinite refresh).
This is quite basic as it only support boundbing boxes.
But the material can refine the volume shape in anyway the user like.
To overcome this limitation, a voxelisation should be done on the mesh (generating a SDF maybe?) and tested against every volumetric cell.
The system now uses several 3D textures in order to decouple every steps of the volumetric rendering.
See https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite for more details.
On the technical side, instead of using a compute shader to populate the 3D textures we use layered rendering with a geometry shader to render 1 fullscreen triangle per 3D texture slice.
This was cause by a fairly funky unitialize buffer (last frame) that was causing NANs during the SSR resolve stage.
They were then propagated to the whole image during the next swap.
Bypassing the SSR completly if no valid history exists fixes the problem. Also disabling SSR data output in this case so we can have correct reflection in the 1st history buffer.
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.
