- Adds tint control, which simulates volumetric absorption inside the coating.
This results in angle-dependent saturation and affects all underlying layers
(diffuse, subsurface, metallic, transmission). It provides a physically-based
alternative to ad-hoc effects such as tinted specular highlights.
- Renames the component from "Clearcoat" to "Coat", since it's no longer
necessarily clear now. This matches naming in e.g. other renderers or OpenPBR.
- Adds an explicit Coat IOR input, in preparation for future smarter IOR logic
around the interaction between Coat and main IOR. This used to be hardcoded
to 1.5.
- Removes hardcoded 0.25 weight multiplier, and adds versioning code to update
existing files accordingly. OBJ import/export still applies the factor.
- Replaces the GTR1 microfacet component with regular GGX. This removes a corner
case in the Microfacet code, solves #53038, and makes us more consistent with
other standard surface shaders. The original Disney BSDF used GTR1, but it
doesn't appear that it caught on in the industry.
Co-authored-by: Weizhen Huang <weizhen@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/110993
was mixing real geometry normal, smoothed geometry normal and
bump-mapped normal.
Use `(sd->type & PRIMITIVE_CURVE) ? sc->N : sd->Ng` consistently instead.
We already have two other functions doing very much the same thing.
`bsdf_microfacet_sample()` seems to be the only place where this
function was used; there we always sample visible normals, so the extra
`inside` check is not needed.
1. move early-out logic even earlier
2. reduced the scope of some variables
3. return `label` at the end of `bsdf_microfacet_sample()`. Return
`LABEL_NONE` in the invalid case. The previous distinction was
unnecessary because samples with zero contribution are assigned with
`LABEL_NONE` in `integrate_surface_bsdf_bssrdf_bounce()` anyway.
the motivation was to give closures with low weight a higher pdf to pick
at the first bounce, in case the next interaction has high contribution.
However, there are several issues:
1. this is too much fine-tuned for a specific case, and only works well
when there is a strong contribution after reflection and very little
contribution after the transmission;
2. the logic in `bsdf_microfacet.h` was added when merging reflection
and refraction into a glass closure, since then it doesn't even work
well in the above case when mixed with other closures;
3. The behavior is inconsistent in `bsdf_microfacet_eval()` and
`bsdf_microfacet_sample()`;
4. such cases should be handled by more modern and more general methods
such as path guiding and denoiser;
5. it makes the code flow harder to follow
Delete this trick for now to pick the closures solely based on their
`sample_weight`. Can be added back (with proper fix in
`bsdf_microfacet`) if indeed necessary.
The API for the kernels library is defined, there is no need to
export more than that. This change only affects linux since hidden
visiblity is the default on Windows.
Curve normal is not available in legacy particle hair system. Construct
a local coordinate system instead of using a fixed normal direction [1,
0, 0] to avoid black appearance.
Use the common BVH utilities header for this.
Added a special type qualifier ccl_ray_data which is defined to ccl_private
for all platforms but Metal. On Metal it is defined to ray_data.
The tricky part is that the BVH utilities are wrapped into the Metal context
class. In some of the BVH functions the context has been already constructed,
but it wasn't done in all the callbacks.
From a quick render tests of the Junkshop benchmark scene there is no render
time difference,
No functional changes are expected.
Pull Request: https://projects.blender.org/blender/blender/pulls/111967
Cycles oneAPI kernel library was compiled using -ffast-math. The current
version of Clang makes it link to crtfastmath.o in that case, bringing a
static constructor that does set the FTZ/DAZ bits in MXCSR for the whole
program, leading to unwanted behavior with other components.
Instead of -ffast-math, we switch to a safer subset of compile flags.
Pull Request: https://projects.blender.org/blender/blender/pulls/111708
based on concentric disk mapping.
Concentric disk mapping was already present, but not used everywhere.
Now `sample_cos_hemisphere()`, `sample_uniform_hemisphere()`, and
`sample_uniform_cone()` use concentric disk mapping.
This changes the noise in many test images.
Pull Request: https://projects.blender.org/blender/blender/pulls/109774
This reverts commit 206ab6437b.
Seems that the illegal address error should be covered elsewhere, but it's not directly
clear where. Revert the commit for further investigation.
Discovered during an investigation into #111277
in rare situations (E.G. When normals are NaN), an emitter
won't be selected as part of `light_tree_cluster_select_emitter()`
and as a result of that, an `emitter_index` of `-1` is passed to
`kernel_data_fetch(light_tree_emitters, emitter_index)` resulting in
an "illegal address" error on some devices.
Pull Request: https://projects.blender.org/blender/blender/pulls/111292
Fixes NaN in Vector Displacement node caused by the normalization of
0, 0, 0 vectors.
This fixes both visual rendering issues and an "illegal address" error
on the GPU. The "illegal address" error came from the Light Tree
Sampling code not handling the NaN normals well, leading to weird code
paths being taken, eventually leading to a kernel_assert and a
user facing illegal address error.
Pull Request: https://projects.blender.org/blender/blender/pulls/111294
Implements the paper [A Microfacet-based Hair Scattering
Model](https://onlinelibrary.wiley.com/doi/full/10.1111/cgf.14588) by
Weizhen Huang, Matthias B. Hullin and Johannes Hanika.
### Features:
- This is a far-field model, as opposed to the previous near-field
Principled Hair BSDF model. The hair is expected to be less noisy, but
lower roughness values takes longer to render due to numerical
integration along the hair width. The hair also appears to be flat when
viewed up-close.
- The longitudinal width of the scattering lobe differs along the
azimuth, providing a higher contrast compared to the evenly spread
scattering in the near-field Principled Hair BSDF model. For a more
detailed comparison, please refer to the original paper.
- Supports elliptical cross-sections, adding more realism as human hairs
are usually elliptical. The orientation of the cross-section is aligned
with the curve normal, which can be adjusted using geometry nodes.
Default is minimal twist. During sampling, light rays that hit outside
the hair width will continue propogating as if the material is
transparent.
- There is non-physical modulation factors for the first three
lobes (Reflection, Transmission, Secondary Reflection).
### Missing:
- A good default for cross-section orientation. There was an
attempt (9039f76928) to default the orientation to align with the curve
normal in the mathematical sense, but the stability (when animated) is
unclear and it would be a hassle to generalise to all curve types. After
the model is in main, we could experiment with the geometry nodes team
to see what works the best as a default.
Co-authored-by: Lukas Stockner <lukas.stockner@freenet.de>
Pull Request: https://projects.blender.org/blender/blender/pulls/105600
The `Find*.cmake` modules originally used uppercase commands to match
CMake's own conventions. Since then CMake uses lower-case and even
within our own find modules, using all uppercase wasn't done
consistently. Opt for lowercase everywhere.
This PR adds the Lacunarity and Normalize inputs to the Noise node
similar to the Voronoi node.
The Lacunarity input controls the scale factor by which each
successive Perlin noise octave is scaled. Which was previously hard
coded to a factor of 2.
The Noise node normalizes its output to the [0, 1] range by default.
The Normalize option makes it possible for the user to disable that.
To keep the behavior consistent with past versions it is enabled by
default.
To make the aforementioned normalization control easer to implement,
the fractal noise code now accumulates signed noise and remaps the
final sum, as opposed to accumulating positive [0, 1] noise.
Pull Request: https://projects.blender.org/blender/blender/pulls/110839
Overall, this commit reworks the component layering in the Principled BSDF
in order to ensure that energy is preserved and conserved.
This includes:
- Implementing support for the OSL `layer()` function
- Implementing albedo estimation for some of the closures for layering purposes
- The specular layer that the Principled BSDF uses has a proper tabulated
albedo lookup, the others are still approximations
- Removing the custom "Principled Diffuse" and replacing it with the classic
lambertian Diffuse, since the layering logic takes care of energy now
- Making the merallic component independent of the IOR
Note that this changes the look of the Principled BSDF noticeably in some
cases, but that's needed, since the cases where it looks different are the
ones that strongly violate energy conservation (mostly grazing reflections
with strong Specular).
Pull Request: https://projects.blender.org/blender/blender/pulls/110864
Many calls to add_check_c_compiler_flag add_check_cxx_compiler_flag
resulted in over long lines & visual noise. Replace with a function that
takes multiple (cache_var flag) pairs to reduce duplication.
Both the `Math` node and the `Vector Math` currently only explicitly
support modulo using truncated division which is oftentimes not the
type of modulo desired as it behaves differently for negative numbers
and positive numbers.
Floored Modulo can be created by either using the `Wrap` operation or
a combination of multiple `Math` nodes. However both methods obfuscate
the actual intend of the artist and the math operation that is actually
used.
This patch adds modulo using floored division to the scalar `Math` node,
explicitly stating the intended math operation and renames the already
existing `"Modulo"` operation to `"Truncated Modulo"` to avoid confusion.
Only the ui name is changed, so this should not break compatibility.
Pull Request: https://projects.blender.org/blender/blender/pulls/110728
This pull request covers up a subtle difference between the CPU and GPU
when rendering with a light tree. Specifically a case where the user
has a sun light with a small angle.
The difference was caused by the dot() function being different between
CPU and GPU backends, with the GPU showing more meaningful
floating-point precision losses when working with small suns.
Pull Request: https://projects.blender.org/blender/blender/pulls/110307
The issue was an out-of-bounds read access when checking whether
the world volume emission needs to be accumulated.
Solution is to check for this case. Done in the generic place, so
that the shade_volume kernel is more readable and no branching
added there, and there is no impact on scenes without the light
linking.
Assume that the world emissive volume belongs to the default light
linking group, as there is no way to link it explicitly to anything.
Pull Request: https://projects.blender.org/blender/blender/pulls/110733
This replaces the Sheen model used in the Principled BSDF with the
model from #108869 that is already used in the Sheen BSDF now.
The three notable differences are:
- At full intensity (Sheen = 1.0), the new model is significantly
stronger than the old one. For existing files, the intensity is
adjusted to keep the overall look similar.
- The Sheen Tint input is now a color input, instead of the
previous blend factor between white and the base color.
- There is now a Sheen roughness control, which can be used to
tweak the look between velvet-like and dust-like.
Pull Request: https://projects.blender.org/blender/blender/pulls/109949
<algorithm> header include is missing from some sycl headers, this will
be fixed upstream with https://github.com/intel/llvm/pull/10424,
meanwhile, we work around it by including it directly.
This is only used as temporary state while evaluating SVM nodes,
there's no point in storing it in the ShaderData for later.
Since ShaderData size is relevant for GPU performance, we should
save the space and only keep it where needed.
Pull Request: https://projects.blender.org/blender/blender/pulls/110366
