Changes to the kernel source would not update the HIP RT binaries, leading
to render errors due to the kernel being mismatched with Blender.
The code this was copied from was inside a macro that defines the sources
variable, but it's not defined here.
Ref #109418
Pull Request: https://projects.blender.org/blender/blender/pulls/110073
this option was already unselectable in the UI, and is treated as GGX
with zero roughness. Upon building the shader graph, we only convert a
closure to `SHARP` when option Filter Glossy is not used and the
roughness is below certain threshold. The benefit is that we can avoid
calling `bsdf_eval()` or return earlier in some cases, but the thresholds
vary across files.
This patch removes `SHARP` closures altogether, and checks if the
roughness value is below a global threshold `BSDF_ROUGHNESS_THRESH`
after blurring, in which case the flag `SD_BSDF_HAS_EVAL` is not set.
The global threshold is set to be `5e-7f` because threshold smaller than
that seems to have caused problem in the past (c6aa0217ac). Also removes
a bunch of functions, variables and arguments that were only there
because we converted closures under certain conditions.
Pull Request: https://projects.blender.org/blender/blender/pulls/109902
The Voronoi distance output is clamped at 8, which is apparent for distance
metrics like Minkowski with low exponents.
This patch fixes that by setting the initial distance of the search loop to
FLT_MAX instead of 8. And for the Smooth variant of F1, the "h" parameter is set
to 1 for the first iteration using a signal value, effectively ignoring the
initial distance and using the computed distance at the first iteration instead.
Pull Request: https://projects.blender.org/blender/blender/pulls/109286
Using area-preserving mapping from cone to disk. Has somewhat distortion
near 90°.
The texture rotates with the transformation of the light object, can
have negative and non-uniform scaling.
Pull Request: https://projects.blender.org/blender/blender/pulls/109842
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
The spotlight is now treated as a sphere instead of a view-aligned disk.
The implementation remains almost identical to that of a point light,
except for the spotlight attenuation and spot blend. There is no
attenuation inside the sphere. Ref #108505
Other changes include:
## Sampling
Instead of sampling the disk area, the new implementation samples either
the cone of the visible portion on the sphere or the spread cone, based
on which cone has a smaller solid angle. This reduces noise when the
spotlight has a large radius and a small spread angle.
| Before | After |
| -- | -- |
||
## Texture
Spot light can now project texture using UV coordinates.
<video src="/attachments/6db989d2-7a3c-4b41-9340-f5690d48c4fb"
title="spot_light_texture.mp4" controls></video>
## Normalization
Previously, the normalization factor for the spotlight was \(\pi r^2\),
the area of a disk. This factor has been adjusted to \(4\pi r^2\) to
account for the surface area of a sphere. This change also affects point
light since they share the same kernel type.
## Versioning
Some pipeline uses the `Normal` socket of the Texture Coordinate node for
projection, because `ls->Ng` was set to the incoming direction at the
current shading point. Now that `ls->Ng` corresponds to the normal
direction of a point on the sphere (except when the radius is zero),
we replace these nodes with a combination of the Geometry shader node
and the Vector Transform node, which gives the same result as before.
Example file see https://archive.blender.org/developer/T93676
Pull Request: https://projects.blender.org/blender/blender/pulls/109329
For repeat / extend / mirror mode, both wrap and read_clip functions did
the bounds check. Removing it improves performance between 0.5% and 1.5%
in the classroom scene in one test. Clip mode is unchanged.
Pull Request: https://projects.blender.org/blender/blender/pulls/109304
The Voronoi Smooth F1 mode breaks when the Smoothness is 0 for OSL. This is
due to a zero division in the shader.
To fix this, standard F1 is used when Smoothness is 0.
Pull Request: https://projects.blender.org/blender/blender/pulls/109255
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
When baking only indirect lighting, light sampling is skipped at the
first bounce. However, light evaluation is still done, so depending
on how the MIS weights end up more or less of the direct lighting
still ends up in the bake.
This is most noticeable with background lighting, but can also be
reproduced with e.g. point lights with a large radius.
Pull Request: https://projects.blender.org/blender/blender/pulls/108955
Better to disable than crashing, as we are not expecting a quick fix. The cause
is likely similar to issues with the light tree, which was already disabled.
Ref #104013
The problem here was that when direct light contibutions to baking were
disabled, the kernel just skipped all direct lighting evaluation.
However, at secondary bounces, "direct light" would actually end up
being indirect (since there's an extra bounce along the way), but
we're still skipping it.
Therefore, only apply direct lighting skipping at the first bounce.
This fixes an issue where the light tree sampling algorithm would
discard light samples from groups of distance lights with an angle
greater than 0 when it shouldn't.
Pull Request: https://projects.blender.org/blender/blender/pulls/108832
Fractal noise is the idea of evaluating the same noise function multiple times with
different input parameters on each layer and then mixing the results. The individual
layers are usually called octaves.
The number of layers is controlled with a "Detail" slider.
The "Lacunarity" input controls a factor by which each successive layer gets scaled.
The existing Noise node already supports fractal noise. Now the Voronoi Noise node
supports it as well. The node also has a new "Normalize" property that ensures that
the output values stay in a [0.0, 1.0] range. That is except for the F2 feature where
in rare cases the output may be outside that range even with "Normalize" turned on.
How the individual octaves are mixed depends on the feature and output socket:
- F1/Smooth F1/F2:
- Distance/Color output:
The individual Distance/Color octaves are first multiplied by a factor of
`Roughness ^ (#layers - 1.0)` then added together to create the final output.
- Position output:
Each Position octave gets linearly interpolated with the combined output of the
previous octaves. The Roughness input serves as an interpolation factor with
0.0 resutling in only using the combined output of the previous octaves and
1.0 resulting in only using the current highest octave.
- Distance to Edge:
- Distance output:
The Distance octaves are mixed exactly like the Position octaves for F1/Smooth F1/F2.
It should be noted that Voronoi Noise is a relatively slow noise function, especially
at higher dimensions. Increasing the "Detail" makes it even slower. Therefore, when
optimizing a scene one should consider trying to use simpler noise functions instead
of Voronoi if the final result is close enough.
Pull Request: https://projects.blender.org/blender/blender/pulls/106827
So far, each closure in Cycles was either diffuse OR glossy OR
transmissive, and its color and contributions were assigned
to the corresponding direct/indirect/color passes.
However, since Glass is a single closure now, that is no longer enough,
since glass has both a glossy and a transmissive component.
Therefore, this commit adds support for splitting contributions from
the Glass closure between the two types.
For 4.0, we might want to also use this for Principled Hair since it
also technically has both types, but that would be a change from
the existing result so it's not part of 3.6 yet.
`sd->type` was set to `PRIMITIVE_TRIANGLE` when it should be
`PRIMITIVE_LAMP`.
Function #lights_intersect_impl sets `isect->prim` to `lamp`, which is
passed to function #shader_setup_from_sample. There `prim != PRIM_NONE`
is evaluated to `true`, thus setting `sd->type` to `PRIMITIVE_TRIANGLE`
erroneously. This fix checks `lamp != LAMP_NONE` first, as in all other
usages of #shader_setup_from_sample `LAMP_NONE` is passed as the value
of `lamp`.
Pull Request: https://projects.blender.org/blender/blender/pulls/108769
In Embree, tfar modification is taken into account by rtcIntersect1
only when hits are accepted. In order to overcome this, we now check
manually for a max_t value in the filter function.
Pull Request: https://projects.blender.org/blender/blender/pulls/108706
We should be recording only the N closest hits in case the number of
hits is exceeding the maximum allowed or the size of the hits stack.
Previously, some cases made it record hits beyond the furthest recorded
one due to lack of hit distance check.
