Check was misc-const-correctness, combined with readability-isolate-declaration
as suggested by the docs.
Temporarily clang-format "QualifierAlignment: Left" was used to get consistency
with the prevailing order of keywords.
Pull Request: https://projects.blender.org/blender/blender/pulls/132361
* Use .empty() and .data()
* Use nullptr instead of 0
* No else after return
* Simple class member initialization
* Add override for virtual methods
* Include C++ instead of C headers
* Remove some unused includes
* Use default constructors
* Always use braces
* Consistent names in definition and declaration
* Change typedef to using
Pull Request: https://projects.blender.org/blender/blender/pulls/132361
- Deduplicate Fisheye projection code
- Replace spherical/cartesian conversions with shared helpers
- Replace transforms from/to local coordinate systems with shared helpers
The main type of repeated transform that's not covered here is `to/from_coords`, but with separate values for xy and z (e.g. BSDFs that already computed `dot(wi, N)` earlier, so they only need `dot(wi, X)` and `dot(wi, Y)` later). Could also be replaced, but it would feel weirdly specific for a helper function.
Pull Request: https://projects.blender.org/blender/blender/pulls/125999
This patch implements blue-noise dithered sampling as described by Nathan Vegdahl (https://psychopath.io/post/2022_07_24_owen_scrambling_based_dithered_blue_noise_sampling), which in turn is based on "Screen-Space Blue-Noise Diffusion of Monte Carlo Sampling Error via Hierarchical Ordering of Pixels"(https://repository.kaust.edu.sa/items/1269ae24-2596-400b-a839-e54486033a93).
The basic idea is simple: Instead of generating independent sequences for each pixel by scrambling them, we use a single sequence for the entire image, with each pixel getting one chunk of the samples. The ordering across pixels is determined by hierarchical scrambling of the pixel's position along a space-filling curve, which ends up being pretty much the same operation as already used for the underlying sequence.
This results in a more high-frequency noise distribution, which appears smoother despite not being less noisy overall.
The main limitation at the moment is that the improvement is only clear if the full sample amount is used per pixel, so interactive preview rendering and adaptive sampling will not receive the benefit. One exception to this is that when using the new "Automatic" setting, the first sample in interactive rendering will also be blue-noise-distributed.
The sampling mode option is now exposed in the UI, with the three options being Blue Noise (the new mode), Classic (the previous Tabulated Sobol method) and the new default, Automatic (blue noise, with the additional property of ensuring the first sample is also blue-noise-distributed in interactive rendering). When debug mode is enabled, additional options appear, such as Sobol-Burley.
Note that the scrambling distance option is not compatible with the blue-noise pattern.
Pull Request: https://projects.blender.org/blender/blender/pulls/118479
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.
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 fixes the issue described in https://projects.blender.org/blender/blender/issues/108957.
Instead of modeling distant lights like a disk light at infinity, it models them as cones. This way, the radiance is constant across the entire range of directions that it covers.
For smaller angles, the difference is very subtle, but for very large angles it becomes obvious (here's the file from #108957, the angle is 179°):
| Old | New |
| - | - |
|  |  |
One notable detail is the sampling method: Using `sample_uniform_cone` can increase noise, since the sampling method no longer preserves the stratification of the samples. This is visible in the "light tree multi distant" test scene.
Turns out we can do better, and after a bit of testing I found a way to adapt the concentric Shirley mapping to uniform cone sampling. I hope the comment explains the logic behind it reasonably well.
Here's the result, note that even the noise distribution is the same when using the new sampling:
| Method | Old | New, basic sampling | New, concentric sampling |
| - | - |- | - |
| Image |  |  |  |
| Render time (at higher spp)| 9.03sec | 8.79sec | 8.96sec |
I'm not sure if I got the `light->normalized` handling right, since I don't really know what the expectation from Hydra is here.
Co-authored-by: Weizhen Huang <weizhen@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/108996
for energy preservation and better compatibility with other renderes. Ref: #108505
Point light now behaves the same as a spherical mesh light with the same overall energy (scaling from emission strength to power is \(4\pi^2R^2\)).
# Cycles
## Comparison
| Mesh Light | This patch | Previous behavior |
| -------- | -------- | -------- |
|  |  |  |
The behavior stays the same when `radius = 0`.
| This patch | Previous behavior |
| -------- | -------- |
|  |  |
No obvious performance change observed.
## Sampling
When shading point lies outside the sphere, sample the spanned solid angle uniformly.
When shading point lies inside the sphere, sample spherical direction uniformly when inside volume or the surface is transmissive, otherwise sample cosine-weighted upper hemisphere.
## Light Tree
When shading point lies outside the sphere, treat as a disk light spanning the same solid angle.
When shading point lies inside the sphere, it behaves like a background light, with estimated outgoing radiance
\[L_o=\int f_aL_i\cos\theta_i\mathrm{d}\omega_i=\int f_a\frac{E}{\pi r^2}\cos\theta_i\mathrm{d}\omega_i\approx f_a \frac{E}{r^2}\],
with \(f_a\) being the BSDF and \(E\) `measure.energy` in `light_tree.cpp`.
The importance calculation for `LIGHT_POINT` is
\[L_o=f_a E\cos\theta_i\frac{\cos\theta}{d^2}\].
Consider `min_importance = 0` because maximal incidence angle is \(\pi\), we could substitute \(d^2\) with \(\frac{r^2}{2}\) so the averaged outgoing radiance is \(f_a \frac{E}{r^2}\).
This only holds for non-transmissive surface, but should be fine to use in volume.
# EEVEE
When shading point lies outside the sphere, the sphere light is equivalent to a disk light spanning the same solid angle. The sine of the new half-angle is the tangent of the previous half-angle.
When shading point lies inside the sphere, integrating over the cosine-weighted hemisphere gives 1.0.
## Comparison with Cycles
The plane is diffuse, the blue sphere has specular component.
| Before | |After ||
|---|--|--|--|
|Cycles|EEVEE|Cycles|EEVEE|
|||||
Pull Request: https://projects.blender.org/blender/blender/pulls/108506
Due to floating point differences between importance sampling and
texture evaluation, disagreeing on whether or not a ray lies within
the sun disc.
* Use the same input values for geographical_to_direction() in
sky_radiance_nishita() and kernel_data.background.sun.
* The mathematical operations in pdf_uniform_cone() were adjusted to
match sky_radiance_nishita().
Pull Request: https://projects.blender.org/blender/blender/pulls/106764
wi is the viewing direction, and wo is the illumination direction. Under this notation, BSDF sampling always samples from wi and outputs wo, which is consistent with most of the papers and mitsuba. This order is reversed compared with PBRT, although PBRT also traces from the camera.
This is done based on the render sample count so that it doesn't impact
sampling quality. It's similar in spirit to the adaptive table size in D16561,
but in this case for performance rather than memory usage.
Differential Revision: https://developer.blender.org/D16726
The first two dimensions of scrambled, shuffled Sobol and shuffled PMJ02 are
equivalent, so this makes no real difference for the first two dimensions.
But Sobol allows us to naturally extend to more dimensions.
Pretabulated Sobol is now always used, and the sampling pattern settings is now
only available as a debug option.
This in turn allows the following two things (also implemented):
* Use proper 3D samples for combined lens + motion blur sampling. This
notably reduces the noise on objects that are simultaneously out-of-focus
and motion blurred.
* Use proper 3D samples for combined light selection + light sampling.
Cycles was already doing something clever here with 2D samples, but using
3D samples is more straightforward and avoids overloading one of the
dimensions.
In the future this will also allow for proper sampling of e.g. volumetric
light sources and other things that may need three or four dimensions.
Differential Revision: https://developer.blender.org/D16443
This resolves some issues with correlation artifacts at higher sample counts.
Fix T101356, correlation issues in new PMJ pattern.
Differential Revision: https://developer.blender.org/D16561
This uses the same sample classification approach as used for PMJ,
because it turns out to also work equally well with Sobol-Burley.
This also implements a fallback (random classification) that should
work "okay" for other samplers, though there are no other samplers
at the moment.
Differential Revision: https://developer.blender.org/D15845
The multi-dimensional Sobol pattern required us to carefully use as low
dimensions as possible, as quality goes down in higher dimensions. Now that we
have two sampling patterns that are at least as good, there is no need to keep
it around and the implementation can be simplified.
Differential Revision: https://developer.blender.org/D15788
Fix two issues in the previous implementation:
* Only power-of-two prefixes were progressively stratified, not suffixes.
This resulted in unnecessarily increased noise when using non-power-of-two
sample counts.
* In order to try to get away with just a single sample pattern, the code
used a combination of sample index shuffling and Cranley-Patterson rotation.
Index shuffling is normally fine, but due to the sample patterns themselves
not being quite right (as described above) this actually resulted in
additional increased noise. Cranley-Patterson, on the other hand, always
increases noise with randomized (t,s) nets like PMJ02, and should be avoided
with these kinds of sequences.
Addressed with the following changes:
* Replace the sample pattern generation code with a much simpler algorithm
recently published in the paper "Stochastic Generation of (t, s) Sample
Sequences". This new implementation is easier to verify, produces fully
progressively stratified PMJ02, and is *far* faster than the previous code,
being O(N) in the number of samples generated.
* It keeps the sample index shuffling, which works correctly now due to the
improved sample patterns. But it now uses a newer high-quality hash instead
of the original Laine-Karras hash.
* The scrambling distance feature cannot (to my knowledge) be implemented with
any decorrelation strategy other than Cranley-Patterson, so Cranley-Patterson
is still used when that feature is enabled. But it is now disabled otherwise,
since it increases noise.
* In place of Cranley-Patterson, multiple independent patterns are generated
and randomly chosen for different pixels and dimensions as described in the
original PMJ paper. In this patch, the pattern selection is done via
hash-based shuffling to ensure there are no repeats within a single pixel
until all patterns have been used.
The combination of these fixes brings the quality of Cycles' PMJ sampler in
line with the previously submitted Sobol-Burley sampler in D15679. They are
essentially indistinguishable in terms of quality/noise, which is expected
since they are both randomized (0,2) sequences.
Differential Revision: https://developer.blender.org/D15746
Based on the paper "Practical Hash-based Owen Scrambling" by Brent Burley,
2020, Journal of Computer Graphics Techniques.
It is distinct from the existing Sobol sampler in two important ways:
* It is Owen scrambled, which gives it a much better convergence rate in many
situations.
* It uses padding for higher dimensions, rather than using higher Sobol
dimensions directly. In practice this is advantagous because high-dimensional
Sobol sequences have holes in their sampling patterns that don't resolve
until an unreasonable number of samples are taken. (See Burley's paper for
details.)
The pattern reduces noise in some benchmark scenes, however it is also slower,
particularly on the CPU. So for now Progressive Multi-Jittered sampling remains
the default.
Differential Revision: https://developer.blender.org/D15679
* Rename "texture" to "data array". This has not used textures for a long time,
there are just global memory arrays now. (On old CUDA GPUs there was a cache
for textures but not global memory, so we used to put all data in textures.)
* For CUDA and HIP, put globals in KernelParams struct like other devices.
* Drop __ prefix for data array names, no possibility for naming conflict now that
these are in a struct.
* Replace license text in headers with SPDX identifiers.
* Remove specific license info from outdated readme.txt, instead leave details
to the source files.
* Add list of SPDX license identifiers used, and corresponding license texts.
* Update copyright dates while we're at it.
Ref D14069, T95597
This patch contains many small leftover fixes and additions that are
required for Metal-enablement:
- Address space fixes and a few other small compile fixes
- Addition of missing functionality to the Metal adapter headers
- Addition of various scattered `__KERNEL_METAL__` blocks (e.g. for
atomic support & maths functions)
Ref T92212
Differential Revision: https://developer.blender.org/D13263
Adds scrambling distance to the PMJ sampler. This is based
on the work by Mathieu Menuet in D12318 who created the original
implementation for the Sobol sampler.
Reviewed By: brecht
Maniphest Tasks: T92181
Differential Revision: https://developer.blender.org/D12854
Cycles:Distance Scrambling for Cycles Sobol Sampler
This option implements micro jittering an is based on the INRIA
research paper [[ https://hal.inria.fr/hal-01325702/document | on micro jittering ]]
and work by Lukas Stockner for implementing the scrambling distance.
It works by controlling the correlation between pixels by either using
a user supplied value or an adaptive algorithm to limit the maximum
deviation of the sample values between pixels.
This is a follow up of https://developer.blender.org/D12316
The PMJ version can be found here: https://developer.blender.org/D12511
Reviewed By: leesonw
Differential Revision: https://developer.blender.org/D12318
Remove prefix of filenames that is the same as the folder name. This used
to help when #includes were using individual files, but now they are always
relative to the cycles root directory and so the prefixes are redundant.
For patches and branches, git merge and rebase should be able to detect the
renames and move over code to the right file.
* Split render/ into scene/ and session/. The scene/ folder now contains the
scene and its nodes. The session/ folder contains the render session and
associated data structures like drivers and render buffers.
* Move top level kernel headers into new folders kernel/camera/, kernel/film/,
kernel/light/, kernel/sample/, kernel/util/
* Move integrator related kernel headers into kernel/integrator/
* Move OSL shaders from kernel/shaders/ to kernel/osl/shaders/
For patches and branches, git merge and rebase should be able to detect the
renames and move over code to the right file.
