**Problem**:
Area lights in Cycles have spread angle, in which case some part of the area light might be invisible to a shading point. The current implementation samples the whole area light, resulting some samples invisible and thus simply discarded. A technique is applied on rectangular light to sample a subset of the area light that is potentially visible (rB3f24cfb9582e1c826406301d37808df7ca6aa64c), however, ellipse (including disk) area lights remained untreated. The purpose of this patch is to apply a techniques to ellipse area light.
**Related Task**:
T87053
**Results**:
These are renderings before and after the patch:
|16spp|Disk light|Ellipse light|Square light (for reference, no changes)
|Before|{F13996789}|{F13996788}|{F13996822}
|After|{F13996759}|{F13996787}|{F13996852}
**Explanation**:
The visible region on an area light is found by drawing a cone from the shading point to the plane where the area light lies, with the aperture of the cone being the light spread.
{F13990078,height=200}
Ideally, we would like to draw samples only from the intersection of the area light and the projection of the cone onto the plane (forming a circle). However, the shape of the intersection is often irregular and thus hard to sample from directly.
{F13990104,height=200}
Instead, the current implementation draws samples from the bounding rectangle of the intersection. In this case, we still end up with some invalid samples outside of the circle, but already much less than sampling the original area light, and the bounding rectangle is easy to sample from.
{F13990125}
The above technique is only applied to rectangle area lights, ellipse area light still suffers from poor sampling. We could apply a similar technique to ellipse area lights, that is, find the
smallest regular shape (rectangle, circle, or ellipse) that covers the intersection (or maybe not the smallest but easy to compute).
For disk area light, we consider the relative position of both circles. Denoting `dist` as the distance between the centre of two circles, and `r1`, `r2` their radii. If `dist > r1 + r2`, the area light is completely invisible, we directly return `false`. If `dist < abs(r1 - r2)`, the smaller circle lies inside the larger one, and we sample whichever circle is smaller. Otherwise, the two circles intersect, we compute the bounding rectangle of the intersection, in which case `axis_u`, `len_u`, `axis_v`, `len_v` needs to be computed anew. Depending on the distance between the two circles, `len_v` is either the diameter of the smaller circle or the length of the common chord.
|{F13990211,height=195}|{F13990225,height=195}|{F13990274,height=195}|{F13990210,height=195}
|`dist > r1 + r2`|`dist < abs(r1 - r2)`|`dist^2 < abs(r1^2 - r2^2)`|`dist^2 > abs(r1^2 - r2^2)`
For ellipse area light, it's hard to find the smallest bounding shape of the intersection, therefore, we compute the bounding rectangle of the ellipse itself, then treat it as a rectangle light.
|{F13990386,height=195}|{F13990385,height=195}|{F13990387,height=195}
We also check the areas of the bounding rectangle of the intersection, the ellipse (disk) light, and the spread circle, then draw samples from the smallest shape of the three. For ellipse light, this also detects where one shape lies inside the other. I am not sure if we should add this measure to rectangle area light and sample from the spread circle when it has smaller area, as we seem to have a better sampling technique for rectangular (uniformly sample the solid angle). Maybe we could add [area-preserving parameterization for spherical
ellipse](https://arxiv.org/pdf/1805.09048.pdf) in the future.
**Limitation**:
At some point we switch from sampling the ellipse to sampling the rectangle, depending on the area of the both, and there seems to be a visible line (with |slope| =1) on the final rendering
which demonstrate at which point we switch between the two methods. We could see that the new sampling method clearly has lower variance near the boundaries, but close to that visible line,
the rectangle sampling method seems to have larger variance. I could not spot any bug in the implementation, and I am not sure if this happens because different sampling patterns for ellipse and rectangle are used.
|Before (256spp)|After (256spp)
|{F13996995}|{F13996998}
Differential Revision: https://developer.blender.org/D16694
Part of the workaround for NVIDIA driver issue got lost in the changes to
switch to the GPU module.
Differential Revision: https://developer.blender.org/D16709
This updates the libraries dependencies for VFX platform 2023, and adds various
new libraries. It also enables Python bindings and switches from static to
shared for various libraries.
The precompiled libraries for all platforms will be updated to these new
versions in the coming weeks.
New:
Fribidi 1.0.12
Harfbuzz 5.1.0
MaterialX 1.38.6 (shared lib with python bindings)
Minizipng 3.0.7
Pybind11 2.10.1
Shaderc 2022.3
Vulkan 1.2.198
Updated:
Boost 1.8.0 (shared lib)
Cython 0.29.30
Numpy 1.23.2
OpenColorIO 2.2.0 (shared lib with python bindings)
OpenImageIO 2.4.6.0 (shared lib with python bindings)
OpenSubdiv 3.5.0
OpenVDB 10.0.0 (shared lib with python bindings)
OSL 1.12.7.1 (enable nvptx backend)
TBB (shared lib)
USD 22.11 (shared lib with python bindings, enable hydra)
yaml-cpp 0.8.0
Includes contributions by Ray Molenkamp, Brecht Van Lommel, Georgiy Markelov
and Campbell Barton.
Ref T99618
Ensure the environment is set up for blender_test, idiff and oslc so that they
can find the required shared libraries.
Also deduplicate add_bundled_libraries() between Linux and macOS.
Includes contributions by Ray Molenkamp and Brecht Van Lommel.
Ref T99618
This patch adds a new `max_working_set_exceeded()` check on Metal so that we can display a "System is out of GPU memory" message to the user. Without this, we get obtuse "CommandBuffer failed" errors at render time due to exceeding the size limit of resident resources.
Likely fix for T101787 & T102786.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D16713
Bugs that caused wrong renders should be fixed now, and tests that showed minor
floating point differences on platforms were tweaked to sidestep the problem.
Ref T77889
Cursor motion events on windows read the position from GetCursorPos()
which wasn't always the same location stored in `lParam`.
In situations where events were handled immediately this wasn't often a
problem, for heavier scenes or when updates between event handling was
slow - many in-between cursor events would be incorrect.
This behavior dates back to the initial commit, there doesn't seem to be
a good reason not to use the cursor coordinates from the event.
Noticed when investigating T102346.
Make OpenGL errors match formatting used by GCC & clang
(as well as Blender's logging), so utilities that recognize this
convention can be used to quickly access this location.
Uses a light tree to more effectively sample scenes with many lights. This can
significantly reduce noise, at the cost of a somewhat longer render time per
sample.
Light tree sampling is enabled by default. It can be disabled in the Sampling >
Lights panel. Scenes using light clamping or ray visibility tricks may render
different as these are biased techniques that depend on the sampling strategy.
The implementation is currently disabled on AMD HIP. This is planned to be fixed
before the release.
Implementation by Jeffrey Liu, Weizhen Huang, Alaska and Brecht Van Lommel.
Ref T77889
This was not working well in non-trivial scenes before the light tree, and now
it is even harder to make it work well with the light tree. It would average the
with equal weight for every light object regardless of intensity or distance, and
be quite noisy due to not working with multiple importance sampling.
We may restore this if were enough good use cases for the previous implementation,
but let's wait and see what the feedback is.
Some uses cases for this have been replaced by the shadow catcher passes, which
did not exist when this was added.
Ref T77889
It is not really used from any of the sources, including the
standalone app. Since we are moving to a more backend-independent
drawing it makes sense to remove header which was specific to
how Blender integrates Cycles into viewport.
There is probably some cleanup in CMake files is possible, but
there is some inter-dependency with USD.
Differential Revision: https://developer.blender.org/D16681
This change fixes issues with viewport rendering when Metal
GPU backend is used for drawing. This is not a default build
configuration and requires the following tweaks:
- Enable WITH_METAL_BACKEND CMake option (set it to on)
- Use `--gpu-backend metal` command line arguments
It also helps using the `--factory-startup` command line
argument to ensure Eevee is not used (it is not ported and
will crash).
The root of the problem was in the use of glViewport().
It is replaced with the GPU_viewport_size_get_i() which
is supposed to be portable equivalent form the GPU module.
Without this change the viewport size is detected to be 0
which backfired in few places.
The rest of the changes were to make the code more robust
in the extreme conditions instead of asserting or crashing.
Simplified and streamlined GPU resources creation in the
display driver. It was a bit convoluted mix of creation of
the GPU resources and resizing them to the proper size. It
even seemed to be done in the reverse order. Now it is as
simple as "just ensure GPU resources are there for the
given texture or buffer size".
Also avoid division by zero in the tile manager.
Differential Revision: https://developer.blender.org/D16679
To make GPU backends other than OpenGL work. Adds required pixel buffer and
fence objects to GPU module.
Authored by Apple: Michael Parkin-White
Ref T96261
Ref T92212
Reviewed By: fclem, brecht
Differential Revision: https://developer.blender.org/D16042
In this case the blocksize may not the one we requested, which was assumed to be
the case. Instead get the effective block size from the compiler as was already
done for Metal and OneAPI.
Unless using WITH_CYCLES_DEBUG.
This is convenient for investigating kernel performance, but too verbose to
always have in the buildbot logs especially now that we are also compiling HIP
and OneAPI kernels.
Materials now have an enum to set the emission sampling method, to be
either None, Auto, Front, Back or Front & Back. This replace the
previous "Multiple Importance Sample" option.
Auto is the new default, and uses a heuristic to estimate the emitted
light intensity to determine of the mesh should be considered as a light
for sampling. Shaders sometimes have a bit of emission but treating them
as a light source is not worth the memory/performance overhead.
The Front/Back settings are not important yet, but will help when a
light tree is added. In that case setting emission to Front only on
closed meshes can help ignore emission from inside the mesh interior that
does not contribute anything.
Includes contributions by Brecht Van Lommel and Alaska.
Ref T77889
* Split light types into own files, move light type specific code from
light tree and MNEE.
* Move flat light distribution code into own kernel file and host side
building function, in preparation of light tree addition. Add light/sample.h
as main entry point to kernel light sampling.
* Better separate calculation of pdf for selecting a light, and pdf for
sampling a point on the light. The selection pdf is now also stored in
LightSampling for MNEE to correctly recalculate the full pdf when the
shading position changes but the point on the light remains fixed.
* Improvement to kernel light storage, using packed_float3, better variable
names, etc.
Includes contributions by Brecht Van Lommel and Weizhen Huang.
Ref T77889
Caused by a8a454287a which assumed it was possible
to access the raw data of the edge creases layer. Also allow
processing vertex creases even if there aren't any edge creases.
The wrong guiding distribution was used when direct and indirect light
scattering happened at different locations. Now use a different distribution
for each location.
Recording is not quite correct since OpenPGL does not support spliting the
path like this, instead recording at the start of the volume ray. In practice
this seems to make little difference.
Differential Revision: https://developer.blender.org/D16448
