Applies thin film iridescence to metals in Metallic BSDF and Principled BSDF.
To get the complex IOR values for each spectral band from F82 Tint colors,
the code uses the parametrization from "Artist Friendly Metallic Fresnel",
where the g parameter is set to F82. This IOR is used to find the phase shift,
but reflectance is still calculated with the F82 Tint formula after adjusting
F0 for the film's IOR.
Co-authored-by: Lukas Stockner <lukas@lukasstockner.de>
Co-authored-by: Weizhen Huang <weizhen@blender.org>
Co-authored-by: RobertMoerland <rmoerlandrj@gmail.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/141131
This PR adds a new `fresnel_conductor_polarized` function, which calculates reflectance and phase shift (if requested) for both parallel and perpendicular polarized light. This is needed for applying thin film iridescence to conductors (see !141131).
For consistency, this PR also makes `fresnel_conductor` call `fresnel_conductor_polarized` instead of using a fast approximation of the Fresnel equations that is inaccurate at lower n and k values. This will change the output of some Metallic BSDF renders using Physical Conductor and prevent discrepancies when enabling thin film iridescence.
I didn't do any rigorous performance testing, but from timing the functions outside of Blender, `fresnel_conductor_polarized` is significantly slower than the approximation, between 1.5-3x depending on the compiler. This makes sense because it has three square roots and the approximation has none. In some informal tests with metallic_multiggx_physical.blend modified to have more spheres, the new renders took around 1-2% longer on both CPU and GPU.
There are some avoidable inefficiencies in this approach of just calling `fresnel_conductor_polarized`:
- one of the three square roots could be saved since `fresnel_conductor` never needs the phase shift and there are simplifications possible when only calculating the reflectance
- there are several unnecessary multiplications by 1.0 since `fresnel_conductor` uses relative IOR and `fresnel_conductor_polarized` doesn't, though those could get optimized out if inlined
Pull Request: https://projects.blender.org/blender/blender/pulls/143903
This changes the engine identifier back to `BLENDER_EEVEE`.
We keep the `BLENDER_EEVEE_NEXT` identifier around for
versioning reasons (have to detect when it is the active
engine of a older file).
This also rename a bunch of pannels that were using `next`
in their name.
This is a breaking change for Addons compatibility.
Pull Request: https://projects.blender.org/blender/blender/pulls/140282
The 2D->2D, 3D->3D, 4D->4D hash functions used in Voronoi node were
using quite an expensive hash function. Switch these to dedicated
2D/3D/4D hash functions (pcg2d, pcg3d, pcg4d) -- these are still very
good quality, but the hash function itself is 3x-4x faster.
Which makes Voronoi node calculation overall be around 2x faster. In
some cases when using OSL, the speedup is even larger.
This visibly changes output of the Voronoi noise however. The actual
noise "behaves" the same, just if someone was depending on the noise
pattern being exactly like it was before, this will change the pattern.
Images, more performance results and details wrt OSL are in the PR.
Pull Request: https://projects.blender.org/blender/blender/pulls/139520
This change moves the tests data files and publish folder of assets
repository to the main blender.git repository as LFS files.
The goal of this change is to eliminate toil of modifying tests,
cherry-picking changes to LFS branches, adding tests as part of a
PR which brings new features or fixes.
More detailed explanation and conversation can be found in the
design task.
Ref #137215
Pull Request: https://projects.blender.org/blender/blender/pulls/137219
