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With a Titan Xp, reduces path trace local memory from 1092MB to 840MB.
Benchmark performance was within 1% with both RX 480 and Titan Xp.
Original patch was implemented by Sergey.
Differential Revision: https://developer.blender.org/D2249
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Similar to what we did for area lights previously, this should help
preserve stratification when using multiple BSDFs in theory. Improvements
are not easily noticeable in practice though, because the number of BSDFs
is usually low. Still nice to eliminate one sampling dimension.
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Benchmarks peformance on GTX 1080 and RX 480 on Linux is the same for
bmw27, classroom, pabellon, and about 2% faster on fishy_cat and koro.
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This was needed when we accessed OSL closure memory after shader evaluation,
which could get overwritten by another shader evaluation. But all closures
are immediatley converted to ShaderClosure now, so no longer needed.
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Also pass by value and don't write back now that it is just a hash for seeding
and no longer an LCG state. Together this makes CUDA a tiny bit faster in my
tests, but mainly simplifies code.
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This implements Arvo's "Stratified sampling of spherical triangles". Similar to how we sample rectangular area lights, this is sampling triangles over their solid angle. It does significantly improve sampling close to the triangle, but doesn't do much for more distant triangles. So I added a simple heuristic to switch between the two methods. Unfortunately, I expect this to add render time in any case, even when it does not make any difference whatsoever. It'll take some benchmarking with various scenes and hardware to estimate how severe the impact is and if it is worth the change.
Reviewers: #cycles, brecht
Reviewed By: #cycles, brecht
Subscribers: Vega-core, brecht, SteffenD
Tags: #cycles
Differential Revision: https://developer.blender.org/D2730
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It uses an idea of accumulating all possible light reachable across the
light path (without taking shadow blocked into account) and accumulating
total shaded light across the path. Dividing second figure by first one
seems to be giving good estimate of the shadow.
In fact, to my knowledge, it's something really similar to what is
happening in the denoising branch, so we are aligned here which is good.
The workflow is following:
- Create an object which matches real-life object on which shadow is
to be catched.
- Create approximate similar material on that object.
This is needed to make indirect light properly affecting CG objects
in the scene.
- Mark object as Shadow Catcher in the Object properties.
Ideally, after doing that it will be possible to render the image and
simply alpha-over it on top of real footage.
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their expected contribution
In scenes with many lights, some of them might have a very small contribution to some pixels, but the shadow rays are traced anyways.
To avoid that, this patch adds probabilistic termination to light samples - if the contribution before checking for shadowing is below a user-defined threshold, the sample will be discarded with probability (1 - (contribution / threshold)) and otherwise kept, but weighted more to remain unbiased.
This is the same approach that's also used in path termination based on length.
Note that the rendering remains unbiased with this option, it just adds a bit of noise - but if the setting is used moderately, the speedup gained easily outweighs the additional noise.
Reviewers: #cycles
Subscribers: sergey, brecht
Differential Revision: https://developer.blender.org/D2217
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When using the Normal output of the Texture Coordinate node on Point and Spot lamps, the coordinates now depend on the rotation of the lamp.
On Area lamps, the Parametric output of the Geometry node now returns UV coordinates on the area lamp.
Credit for the Area lamp part goes to Stefan Werner (from D1995).
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Reviewers: brecht, sergey, dingto, juicyfruit
Differential Revision: https://developer.blender.org/D2220
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Using ones complement for detecting if transform has been applied was confusing
and led to several bugs. With this proper checks are made.
Also added a few transforms where they were missing, mostly affecting baking
and displacement when `P` is used in the shader (previously `P` was in the
wrong space for these shaders)
Also removed `TIME_INVALID` as this may have resulted in incorrect
transforms in some cases.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D2192
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Most of the time, Lamps in Cycles are just a constant emission closure, no texturing etc. Therefore, running a full shader evaluation is wasteful.
To avoid that, Cycles now detects these constant emission shaders and stores their value in the lamp data along with a flag in the shader.
Then, at runtime, if this flag is set, the lamp code just uses this value and only runs the full shader evaluation if it is neccessary.
In scenes with a lot of lamps and with "Sample all direct/indirect" enabled, this saves up to 20% of rendering time in my tests.
Reviewers: #cycles
Differential Revision: https://developer.blender.org/D2193
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Glossy, Anisotropic and Glass BSDFs
This commit adds a new distribution to the Glossy, Anisotropic and Glass BSDFs that implements the
multiple-scattering microfacet model described in the paper "Multiple-Scattering Microfacet BSDFs with the Smith Model".
Essentially, the improvement is that unlike classical GGX, which only models single scattering and assumes
the contribution of multiple bounces to be zero, this new model performs a random walk on the microsurface until
the ray leaves it again, which ensures perfect energy conservation.
In practise, this means that the "darkening problem" - GGX materials becoming darker with increasing
roughness - is solved in a physically correct and efficient way.
The downside of this model is that it has no (known) analytic expression for evalation. However, it can be
evaluated stochastically, and although the correct PDF isn't known either, the properties of MIS and the
balance heuristic guarantee an unbiased result at the cost of slightly higher noise.
Reviewers: dingto, #cycles, brecht
Reviewed By: dingto, #cycles, brecht
Subscribers: bliblubli, ace_dragon, gregzaal, brecht, harvester, dingto, marcog, swerner, jtheninja, Blendify, nutel
Differential Revision: https://developer.blender.org/D2002
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undefined type for lamp objects
The problem here was that there are five path types internally (diffuse, glossy, transmission, subsurface and volume scatter), but subsurface isn't exposed to the user.
This caused some weird behaviour - if all four types are disabled on the lamp, Cycles doesn't even try sampling it, but if any type was active, the lamp would illuminate
the cube since none of the options set subsurface to zero.
In the future, it might be reasonable to add subsurface visibility as an option - but for now the weird and inconsistent behaviour can be fixed simply by setting both
diffuse and subsurface to zero if the user disables diffuse visibility.
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57% less for path and 48% less for branched path.
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Quite straightforward, main trick is happening in path_source_replace_includes().
Reviewers: brecht, dingto, lukasstockner97, juicyfruit
Differential Revision: https://developer.blender.org/D1794
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Use KernelGlobals to access all the global arrays for the intermediate
storage instead of passing all this storage things explicitly.
Tested here with Intel OpenCL, NVIDIA GTX580 and AMD Fiji, didn't see
any artifacts, so guess it's all good.
Reviewers: juicyfruit, dingto, lukasstockner97
Differential Revision: https://developer.blender.org/D1736
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This commit changes the way how we pass bounce information to the Light
Path node. Instead of manualy copying the bounces into ShaderData, we now
directly pass PathState. This reduces the arguments that we need to pass
around and also makes it easier to extend the feature.
This commit also exposes the Transmission Bounce Depth to the Light Path
node. It works similar to the Transparent Depth Output: Replace a
Transmission lightpath after X bounces with another shader, e.g a Diffuse
one. This can be used to avoid black surfaces, due to low amount of max
bounces.
Reviewed by Sergey and Brecht, thanks for some hlp with this.
I tested compilation and usage on CPU (SVM and OSL), CUDA, OpenCL Split
and Mega kernel. Hopefully this covers all devices. :)
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Path Tracing
Multiple importance sampling for branched path tracing light samples needs to be
calculated separately per BSDF, not with Veach's one sample model.
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This commit contains all the work related on the AMD megakernel split work
which was mainly done by Varun Sundar, George Kyriazis and Lenny Wang, plus
some help from Sergey Sharybin, Martijn Berger, Thomas Dinges and likely
someone else which we're forgetting to mention.
Currently only AMD cards are enabled for the new split kernel, but it is
possible to force split opencl kernel to be used by setting the following
environment variable: CYCLES_OPENCL_SPLIT_KERNEL_TEST=1.
Not all the features are supported yet, and that being said no motion blur,
camera blur, SSS and volumetrics for now. Also transparent shadows are
disabled on AMD device because of some compiler bug.
This kernel is also only implements regular path tracing and supporting
branched one will take a bit. Branched path tracing is exposed to the
interface still, which is a bit misleading and will be hidden there soon.
More feature will be enabled once they're ported to the split kernel and
tested.
Neither regular CPU nor CUDA has any difference, they're generating the
same exact code, which means no regressions/improvements there.
Based on the research paper:
https://research.nvidia.com/sites/default/files/publications/laine2013hpg_paper.pdf
Here's the documentation:
https://docs.google.com/document/d/1LuXW-CV-sVJkQaEGZlMJ86jZ8FmoPfecaMdR-oiWbUY/edit
Design discussion of the patch:
https://developer.blender.org/T44197
Differential Revision: https://developer.blender.org/D1200
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This patch adds support for light portals: objects that help sampling the
environment light, therefore improving convergence. Using them tor other
lights in a unidirectional pathtracer is virtually useless.
The sampling is done with the area-preserving code already used for area lamps.
MIS is used both for combination of different portals and for combining portal-
and envmap-sampling.
The direction of portals is considered, they aren't used if the sampling point
is behind them.
Reviewers: sergey, dingto, #cycles
Reviewed By: dingto, #cycles
Subscribers: Lapineige, nutel, jtheninja, dsisco11, januz, vitorbalbio, candreacchio, TARDISMaker, lichtwerk, ace_dragon, marcog, mib2berlin, Tunge, lopataasdf, lordodin, sergey, dingto
Differential Revision: https://developer.blender.org/D1133
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Issue was caused by accident in c8a9a56 which not only disabled glossy
reflection if Glossy visibility is disabled, but also Diffuse reflection.
Quite safe and should go to final release branch.
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There seems to be inconsistency in flags checks in Cycles kernel. In the interface
glossy means "Glossy Reflection" and it is properly taken into account when doing
visibility check in BVH traversal.
The check in indirect background/light emission was treating this flags as "any of
glossy reflection or transmission" which is kind of weird.
Made it so emission code follows ray visibility assumptions in other parts of the
kernel now.
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This was already mixed a bit, but the dot belongs there.
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This adds a new "Volume Scatter" option to the "Ray Visibility" panels and can be used to e.g. exclude lamps from having an influence on the volume. See release logs for an example: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.72/Cycles
Differential revision: https://developer.blender.org/D771
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* Volume multiple importace sampling support to combine equiangular and distance
sampling, for both homogeneous and heterogeneous volumes.
* Branched path "Sample All Direct Lights" and "Sample All Indirect Lights" now
apply to volumes as well as surfaces.
Implementation note:
For simplicity this is all done with decoupled ray marching, the only case we do
not use decoupled is for distance only sampling with one light sample. The
homogeneous case should still compile on the GPU because it only requires fixed
size storage, but the heterogeneous case will be trickier to get working.
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Probably will not be noticed in most scenes. This helps reduce noise when you
have multiple lamps with MIS enabled, at the cost of some performance, but from
testing some scenes this seems better.
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Differential Revision: https://developer.blender.org/D477
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This was the original code to get things working on old GPUs, but now it is no
longer in use and various features in fact depend on this to work correctly to
the point that enabling this code is too buggy to be useful.
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This can for example be useful if you want to manually terminate the path at
some point and use a color other than black.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D454
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sampling.
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This is done by adding a Volume Scatter node. In many cases you will want to
add together a Volume Absorption and Volume Scatter node with the same color
and density to get the expected results.
This should work with branched path tracing, mixing closures, overlapping
volumes, etc. However there's still various optimizations needed for sampling.
The main missing thing from the volume branch is the equiangular sampling for
homogeneous volumes.
The heterogeneous scattering code was arranged such that we can use a single
stratified random number for distance sampling, which gives less noise than
pseudo random numbers for each step. For volumes where the color is textured
there still seems to be something off, needs to be investigated.
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shader.
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This to avoids build conflicts with libc++ on FreeBSD, these __ prefixed values
are reserved for compilers. I apologize to anyone who has patches or branches
and has to go through the pain of merging this change, it may be easiest to do
these same replacements in your code and then apply/merge the patch.
Ref T37477.
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property name back so we keep compatibility.
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More information in this post:
http://code.blender.org/
Thanks to all contributes for giving their permission!
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* Added a Ray Depth output to the Light Path node, which gives the user access to the current bounce.
This can be used to limit the maximum ray bounce on a per shader basis. Another use case is to restrict light influence with this, to have a lamp only contribute to the direct lighting.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/More#Light_Path
This is part of my GSoC 2013 project. SVN merge of r58091 and r58772 from soc-2013-dingto.
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material.
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meshes and lamps. The light path node already made this possible but it's a bit
faster to render this way and convenient.
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without
multiple importance sampling, so you can disable them for diffuse/glossy/transmission.
The Light Path node here is still weak and does not give this info. To make that
work we'd need to evaluate the shader multiple times which is slow and we can't
detect well enough when it is actually needed.
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* Revert r57203 (len() renaming)
There seems to be a problem with nVidia OpenCL after this and I haven't figured out the real cause yet.
Better to selectively enable native length() later, after figuring out what's wrong.
This fixes [#35612].
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* Rename some math functions:
len -> length
len_squared -> length_squared
normalize_len -> normalize_length
* This way OpenCL uses its inbuilt length() function, rather than our own. The other two functions have been renamed for consistency.
* Tested CPU, CUDA and OpenCL compile, should be no functional changes.
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