Cycles samples environment map with a PDF proportional to the luminance.
This computation was assuming positive values, but generated texture
coordinates from world could have negative values, so the resulted CDF
was almost zero in the bug report scene.
Fixed by taking the absolute value when computing luminance in CDF.
Pull Request: https://projects.blender.org/blender/blender/pulls/119896
By restricting the sample range along the ray to the valid segment.
Supports
**Mesh Light**
- [x] restrict the ray segment to the side with MIS
**Area Light**
- [x] when the spread is zero, find the intersection of the ray and the bounding box/cylinder of the rectangle/ellipse area light beam
- [x] when the spread is non-zero, find the intersection of the ray and the minimal enclosing cone of the area light beam
*note the result is also unbiased when we just consider the cone from the sampled point in volume segment. Far away from the light source it's less noisy than the current solution, but near the light source it's much noisier. We have to restrict the sample region on the area light to the part that lits the ray then, I haven't tried yet to see if it would be less noisy.*
**Point Light**
- [x] the complete ray segment should be valid.
**Spot Light**
- [x] intersect the ray with the spot light cone
- [x] support non-zero radius
Pull Request: https://projects.blender.org/blender/blender/pulls/119438
For spherical spot light, when the shading point is close to the light
source, we switch to sampling the light spread instead of the visible
cone from the shading point. This has the benefit of less noise when the
spread is small.
However, the light spread sampling was not considering non-uniform
object scaling, where the actual spread might be different.
This patch switches sampling method only when the smallest enclosing
spread cone is smaller than the visible cone from the shading point.
An alternative method would be to compute the actual solid angle of the
scaled cone, and sample from the scaled cone. However, that involves
ray transformation and modifying the sampling pdf and angle. Since
non-uniform scaling is rather a niche case, it's probably not worth the
computation effort.
Pull Request: https://projects.blender.org/blender/blender/pulls/119661
for a camera ray, compute the actual range of the hair width that the
current pixel covers, and only integrate that subset, to prevent a
ribbon-like appearance in close-up looks.
When the hair covers less than one pixel on the screen or when the ray
is not camera ray, the model works the same as before.
Pull Request: https://projects.blender.org/blender/blender/pulls/116094
area light with zero spread was introduced in bf18032977. Such paths can
only be sampled with NEE, so MIS should not be used.
This fixes the discrepancy when Direct Light Sampling is set to MIS or NEE.
Pull Request: https://projects.blender.org/blender/blender/pulls/118584
Add new "Soft Falloff" option on point and spot light that uses
the old light behavior from Blender versions before 4.0. Blend
files saved with those older versions will use the option.
This option is enabled by default on new lights.
Fix#114241
Co-authored-by: Weizhen Huang <weizhen@blender.org>
Co-authored-by: Clément Foucault <foucault.clem@gmail.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/117832
OpenImageDenoise API exposes two modes, high quality and balanced.
This currently only has effect on Nvidia devices, on which it
provides a noticeable performance improvement without visible
difference in quality. This change sets quality to balanced for
the viewport, and high quality for final frame rendering, as
it's what makes the most sense.
Ref #115045
Co-authored-by: Werner, Stefan <stefan.werner@intel.com>
Pull Request: #115265
Along with the 4.1 libraries upgrade, we are bumping the clang-format
version from 8-12 to 17. This affects quite a few files.
If not already the case, you may consider pointing your IDE to the
clang-format binary bundled with the Blender precompiled libraries.
Fixes an issue where triangles (and possibly lights) would not be added
to the light tree if the only visibility option it has enabled is volumetric
scattering.
This would lead to an assert during forward sampling because the light
would be treated as if it was in the light tree, and a light index
outside the light tree array would be sampled, which would trigger
the assert.
Pull Request: https://projects.blender.org/blender/blender/pulls/116703
This was required for OSL, which used to be compiled entirely without
RTTI for LLVM. However OSL now only compiles a private part of its code
without RTTI, so this no longer necessary.
Pull Request: https://projects.blender.org/blender/blender/pulls/116035
OpenImageDenoise has two modes, high quality and balanced. This now exposes the modes as user parameters, with viewport denoising defaulting to balanced and final frame rendering set to high quality.
Ref #115045
Co-authored-by: Werner, Stefan <stefan.werner@intel.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/115265
This path merges the Musgrave and Noise Texture nodes into a single
combined Noise Texture node. The reasoning is that both nodes
intrinsically do the same thing, which is the layering of Perlin noise
derivatives to produce fractal noise. So the patch de-duplicates code
and unifies the use of fractal noise for the end use.
Since the Noise node had a Distortion input and a Color output, while
the Musgrave node did not, those are now available to the Musgrave types
as new functionalities.
The Dimension input of the Musgrave node is analogous to the Roughness
input of the Noise node, so both inputs were unified to follow the same
behavior of the Roughness input, which is arguable more intuitive to
control. Similarly, the Detail input was slightly different across both
nodes, since the Noise node evaluated one extra layer of noise. This was
also unified to follow the behavior of the Noise node.
The patch, coincidentally fixes an unreported bug causing repeated
output for certain noise types and another floating precision bug
#112180.
The versioning code implemented with this patch ensures backward
compatibility for both the Musgrave and Noise Texture nodes. When
opening older Blender files in Blender 4.1 the output of both nodes are
guaranteed to always be exactly identical to that of Blender files
created before the nodes were merged in all cases.
Forward compatibility with Blender 4.0 is implemented by #114236.
Forward compatibility with Blender 3.6 LTS is implemented by #115015.
Pull Request: #111187
The increased amount of BSDF code from Principled BSDF v2 and the
microfacet BSDF led to a big performance regression on Metal and AMD.
We have not been able to find a good workaround for all scenes.
This change disables the Principled Hair BSDF code when it is not used
in the scene. This makes common benchmark scenes faster, but
performance is still bad in scenes that do use it.
Ref #112596
Pull Request: https://projects.blender.org/blender/blender/pulls/113904
This was a regression after the sphere light changes, where the normal
now is the normal along the geometry of the light and no longer suitable
for the IES texture direction.
This not only fixes point lights with non-zero radius, but makes the IES
texture direction work consistently across light types and meshes,
always rotated by the object transform.
Cycles implements the "Taming the Shadow Terminator" paper by Matt Jen-Yuan
Chiang to solve shadow terminator issues when a bump map is applied, as well
as similar approach for the glossy reflection to ensure ray does not get
reflected to inside of the object.
This correction term is applied unconditionally, which makes it harder to have
full control over shading via normals for stylistic reasons.
This change exposes this corrective term as an option called "Bump Map
Correction" which is available in the shader settings next to the
"Transparent Shadows".
The reason to make it per-shader rather than per-object is to allow flexibility
of a control: it is possible that an object has multiple shaders attached to it,
and only some of them used for bump mapping. Another, and possibly stronger
reason to have it per-shader is ease of assets control: shader brings settings
which are needed for its proper behavior. So if material at some point
decides to take over normals, artists would not need to update settings on
every asset which uses that material.
The option is enabled by default, so there is no changes for existing setups.
Pull Request: https://projects.blender.org/blender/blender/pulls/113480
Update the Glass BSDF to internally use Generalized Schlick fresnel.
This allows for easier expansion of certain features in the future.
There should be no functional change from the users perspective.
Pull Request: https://projects.blender.org/blender/blender/pulls/112701
This was causing a warning when using OSL, since the OSL implementation
didn't implement the input.
Since the socket isn't really implemented on the Blender side anyways,
just get rid of it.
Also, the SVM code uses the shading normal while OSL used the geometric normal.
- Changes defaults from Emission Color 0.0, Emission Strength 1.0 to be the
other way around (Color 1.0, Strength 0.0), suggested by @brecht
- Makes emission component occluded by sheen and coat
(to simulate e.g. dust-covered light sources)
- Moves transparency into the Principled SVM/OSL node, to allow for future
support for e.g. transparent shadows in thin sheet mode.
Note that there are optimization opportunities here (mostly skipping the
non-transparent components for transparent shadow evaluation, and skipping
the parts that don't affect emission for light evaluation), but I have a
separate point for those in the Principled V2 planning since there's some
other optimization topics as well.
Co-authored-by: Weizhen Huang <weizhen@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/111155
Previously, the Principled BSDF used the Subsurface input to scale the radius.
When it was zero, it used a diffuse closure, otherwise a subsurface closure.
This sort of scaling input makes sense, but it should be specified in distance
units, rather than a 0..1 factor, so this commit changes the unit and renames
the input to Subsurface Scale.
Additionally, it adds support for mixing diffuse and subsurface components.
This is part of e.g. the OpenPBR spec, and the logic behind it is to support
modeling e.g. dirt or paint on top of skin. Before, materials would be either
fully diffuse (radius=0) or fully subsurface.
For typical materials, this mixing factor will be either zero or one
(just like metallic or transmission), but supporting fractional inputs makes
sense for e.g. smooth transitions at boundaries.
Another change is that there is no separate Subsurface Color anymore - before,
this was mixed with the Base Color using the Subsurface input as the factor,
but this was not really useful since that input was generally very small.
And finally, the handling of how the path enters the material for random walk
subsurface scattering is changed. Before, this always used lambertian (diffuse)
transmission, but this caused some problems, like overly white edges.
Instead, two different methods are now used, depending on the selected mode.
In Fixed Radius mode, the code assumes a simple medium boundary, and performs
refraction into the material using the main Roughness and IOR inputs.
Meanwhile, when not using Fixed Radius, the code assumes a more complex
boundary (as typically found on organic materials, e.g. skin), so the entry
bounce has a 50/50 chance of being either diffuse transmission or refraction
using the separate Subsurface IOR input and a fixed roughness of 1.
Credit for this method goes to Christophe Hery.
Pull Request: https://projects.blender.org/blender/blender/pulls/110989
Brecht Van Lommel
Weizhen Huang
Campbell Barton
Alaska
Nikita Sirgienko
Lukas Stockner
Werner, Stefan
Stefan Werner
Hoshinova
Sergey Sharybin