This adds path guiding features into Cycles by integrating Intel's Open Path
Guiding Library. It can be enabled in the Sampling > Path Guiding panel in the
render properties.
This feature helps reduce noise in scenes where finding a path to light is
difficult for regular path tracing.
The current implementation supports guiding directional sampling decisions on
surfaces, when the material contains a least one diffuse component, and in
volumes with isotropic and anisotropic Henyey-Greenstein phase functions.
On surfaces, the guided sampling decision is proportional to the product of
the incident radiance and the normal-oriented cosine lobe and in volumes it
is proportional to the product of the incident radiance and the phase function.
The incident radiance field of a scene is learned and updated during rendering
after each per-frame rendering iteration/progression.
At the moment, path guiding is only supported by the CPU backend. Support for
GPU backends will be added in future versions of OpenPGL.
Ref T92571
Differential Revision: https://developer.blender.org/D15286
This commit is a big overhaul to the Mikktspace module, which is used
to compute tangents. I'm not calling it a rewrite since it's the
result of a lot of iterations on the original code, but pretty much
everything is reworked somehow.
Overall goal was to a) make it faster and b) make it maintainable.
Notable changes:
- Since the callbacks for requesting geometry data were a big
bottleneck before, I've ported it to C++ and made it header-only,
templating on the data source. That way, the compiler generates code
specific to the caller, which allows it to inline the data source and
specialize for some cases (e.g. subd vs. non-subd in Cycles).
- The one input parameter, an optional angle threshold, was not used
anywhere. Turns out that removing it allows for considerable
algorithmic simplification, removing a lot of the complexity in the
later stages. Therefore, I've just removed the option in the new code.
- The code computes several outputs, but only one (the tangent itself)
is ever used in Blender. Therefore, I've removed the others to
simplify the code. They could easily be brought back if needed, none
of the algorithmic simplifications are conflicting with them.
- The original code had fallback paths for many steps in case temporary
memory allocation fails, but that never actually gets used anyways
since malloc() doesn't really ever return NULL in practise, so I
removed them.
- In general, I've restructured A LOT of the code to make the
algorithms clearer and make use of some C++ features (vectors,
std::array, booleans, classes), though there's still some of cleanup
that could be done.
- Parallelized duplicate detection, neighbor detection, triangle
tangent computation, degenerate triangle handling and tangent space
accumulation.
- Replaced several algorithms with faster equivalents: Duplicate
detection uses a (concurrent) hash set now, neighbor detection uses
Radixsort and splits vertices by index pairs etc.
As for results, the exact speedup depends on the scene of course, but
let's consider the file from T97378:
- Blender 3.1 (before D14675): 6.07sec
- Blender 3.2 (with D14675): 4.62sec
- rBf0a36599007d (last nightly build): 4.42sec
- With this commit: 0.90sec
This speedup will mostly be noticed at the start of Cycles renders and,
even more importantly, in Eevee when doing something that changes the
geometry (e.g. animating) on a model using normal maps.
Differential Revision: https://developer.blender.org/D15589
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
This cleans up the OpenGL build flags and linking.
It additionally also removes some dead code.
One of these dead code paths is WITH_X11_ALPHA which actually never was
active even with the build flag on. The call to use this was never
called because the default initializer for GHOST was set to have it off
per default. Nothing called this function with a boolean value to enable it.
These cleanups are needed to support true headless OpenGL rendering.
Without these cleanups libepoxy will fail to load the correct OpenGL
Libraries as we have already linked them to the blender binary.
Reviewed By: Brecht, Campbell, Jeroen
Differential Revision: http://developer.blender.org/D15554
With libepoxy we can choose between EGL and GLX at runtime, as well as
dynamically open EGL and GLX libraries without linking to them.
This will make it possible to build with Wayland, EGL, GLVND support while
still running on systems that only have X11, GLX and libGL. It also paves
the way for headless rendering through EGL.
libepoxy is a new library dependency, and is included in the precompiled
libraries. GLEW is no longer a dependency, and WITH_SYSTEM_GLEW was removed.
Includes contributions by Brecht Van Lommel, Ray Molenkamp, Campbell Barton
and Sergey Sharybin.
Ref T76428
Differential Revision: https://developer.blender.org/D15291
This change allows the Cycles progress report system to take into conderation
the time limit property. This allows for more accuracte progress reports for
high sample count renders with short time limits.
Contributed by Alaska.
Differential Revision: https://developer.blender.org/D15599
Detect cases where a ray-intersection would miss the current triangle, which if
the intersection is strictly watertight, implies that a neighboring triangle would
incorrectly be hit instead.
When that is detected, apply a ray-offset. The idea being that we only want to
introduce potential error from ray offsets if we really need to.
This work for BVH2 and Embree, as we are able to match the ray-interesction
bit-for-bit, though doing so for Embree requires ugly hacks. Tiny differences
like fused-multiply-add or dot product intrinstics in matrix inversion and ray
intersection needed to be matched exactly, so this is fragile.
Unfortunately we're not able to do the same for OptiX or MetalRT, since those
implementations are unknown (and possibly impossible to match as hardware
instructions). Still artifacts are much reduced, though not eliminated.
Ref T97259
Differential Revision: https://developer.blender.org/D15559
The performance of this will be slightly more important for upcoming changes.
Also removed an unused function and changed includes so these system.h can
be included in more places.
These replace float3 and packed_float3 in various places in the kernel where a
spectral color representation will be used in the future. That representation
will require more than 3 channels and conversion to from/RGB. The kernel code
was refactored to remove the assumption that Spectrum and RGB colors are the
same thing.
There are no functional changes, Spectrum is still a float3 and the conversion
functions are no-ops.
Differential Revision: https://developer.blender.org/D15535
Now all the same ones are available on CPU and GPU, which was previously not
possible due to lack of operator overloadng in OpenCL. Print functions are
no-ops on some GPUs.
Ref D15535
Caused by 38af5b0501.
Adjust barycentric coordinates used for intersection result in the
ray-to-rectangle intersection check.
Differential Revision: https://developer.blender.org/D15592
Caused by 38af5b0501.
Adjust barycentric coordinates used for intersection result in the
ray-to-rectangle intersection check.
Differential Revision: https://developer.blender.org/D15592
Checking arm64 assembly support before CUDA/Metal would cause NVCC to
generate inline arm64 assembly.
Differential Revision: https://developer.blender.org/D15569
* OneAPI: remove separate float3 definition
* OneAPI: disable operator[] to match other GPUs
* OneAPI: make int3 compact to match other GPUs
* Use #pragma once
* Add __KERNEL_NATIVE_VECTOR_TYPES__ to simplify checks
* Remove unused vector3
Simplifies intersection code a little and slightly improves precision regarding
self intersection.
The parametric texture coordinate in shader nodes is still the same as before
for compatibility.
float8 is a reserved type in Metal, but is not implemented. So rename to
float8_t for now.
Also move back intersection handlers to kernel.metal, they can't be in the
class that encapsulates the other Metal kernel functions.
This was tested in some places to check if code was being compiled for the
CPU, however this is only defined in the kernel. Checking __KERNEL_GPU__
always works.
This patch adds required math functions for float8 to make it possible
using float8 instead of float3 for color data.
Differential Revision: https://developer.blender.org/D15525
For transparency, volume and light intersection rays, adjust these distances
rather than the ray start position. This way we increment the start distance
by the smallest possible float increment to avoid self intersections, and be
sure it works as the distance compared to be will be exactly the same as
before, due to the ray start position and direction remaining the same.
Fix T98764, T96537, hair ray tracing precision issues.
Differential Revision: https://developer.blender.org/D15455
The Metal backend now compiles and caches a second set of kernels which are
optimized for scene contents, enabled for Apple Silicon.
The implementation supports doing this both for intersection and shading
kernels. However this is currently only enabled for intersection kernels that
are quick to compile, and already give a good speedup. Enabling this for
shading kernels would be faster still, however this also causes a long wait
times and would need a good user interface to control this.
M1 Max samples per minute (macOS 13.0):
PSO_GENERIC PSO_SPECIALIZED_INTERSECT PSO_SPECIALIZED_SHADE
barbershop_interior 83.4 89.5 93.7
bmw27 1486.1 1671.0 1825.8
classroom 175.2 196.8 206.3
fishy_cat 674.2 704.3 719.3
junkshop 205.4 212.0 257.7
koro 310.1 336.1 342.8
monster 376.7 418.6 424.1
pabellon 273.5 325.4 339.8
sponza 830.6 929.6 1142.4
victor 86.7 96.4 96.3
wdas_cloud 111.8 112.7 183.1
Code contributed by Jason Fielder, Morteza Mostajabodaveh and Michael Jones
Differential Revision: https://developer.blender.org/D14645
Add more math functions for float4 to make them on par with float3 ones. It
makes it possible to change the types of float3 variables to float4 without
additional work.
Differential Revision: https://developer.blender.org/D15318
This patch adds a new Cycles device with similar functionality to the
existing GPU devices. Kernel compilation and runtime interaction happen
via oneAPI DPC++ compiler and SYCL API.
This implementation is primarly focusing on Intel® Arc™ GPUs and other
future Intel GPUs. The first supported drivers are 101.1660 on Windows
and 22.10.22597 on Linux.
The necessary tools for compilation are:
- A SYCL compiler such as oneAPI DPC++ compiler or
https://github.com/intel/llvm
- Intel® oneAPI Level Zero which is used for low level device queries:
https://github.com/oneapi-src/level-zero
- To optionally generate prebuilt graphics binaries: Intel® Graphics
Compiler All are included in Linux precompiled libraries on svn:
https://svn.blender.org/svnroot/bf-blender/trunk/lib The same goes for
Windows precompiled binaries but for the graphics compiler, available
as "Intel® Graphics Offline Compiler for OpenCL™ Code" from
https://www.intel.com/content/www/us/en/developer/articles/tool/oneapi-standalone-components.html,
for which path can be set as OCLOC_INSTALL_DIR.
Being based on the open SYCL standard, this implementation could also be
extended to run on other compatible non-Intel hardware in the future.
Reviewed By: sergey, brecht
Differential Revision: https://developer.blender.org/D15254
Co-authored-by: Nikita Sirgienko <nikita.sirgienko@intel.com>
Co-authored-by: Stefan Werner <stefan.werner@intel.com>
Enables Vega and Vega II GPUs as well as Vega APU, using changes in HIP code
to support 64-bit waves and a new HIP SDK version.
Tested with Radeon WX9100, Radeon VII GPUs and Ryzen 7 PRO 5850U with Radeon
Graphics APU.
Ref T96740, T91571
Differential Revision: https://developer.blender.org/D15242
This patch unifies the names of math functions for different data types and uses
overloading instead. The goal is to make it possible to swap out all the float3
variables containing RGB data with something else, with as few as possible
changes to the code. It's a requirement for future spectral rendering patches.
Differential Revision: https://developer.blender.org/D15276
For non-raw, non-sRGB color spaces, always use half float even if that uses
more memory. Otherwise the precision loss from conversion to scene linear or
sRGB (as natively understood by the texture sampling) can be too much.
This also required a change to do alpha association ourselves instead of OIIO,
because in OIIO alpha multiplication happens before conversion to half float
and that gives too much precision loss.
Ref T68926
After recent changes to Nishita sky to clamp negative colors, the pixels ended
up a bit brighter which lead to them exceeding the half float max value. The
CUDA float to half function seems to need clamping.
This patch makes it possible to change the precision with which to
store volume data in the NanoVDB data structure (as float, half, or
using variable bit quantization) via the previously unused precision
field in the volume data block.
It makes it possible to further reduce memory usage during
rendering, at a slight cost to the visual detail of a volume.
Differential Revision: https://developer.blender.org/D10023
Inspired by D12936 and D12929, this patch adds general purpose
"Combine Color" and "Separate Color" nodes to Geometry, Compositor,
Shader and Texture nodes.
- Within Geometry Nodes, it replaces the existing "Combine RGB" and
"Separate RGB" nodes.
- Within Compositor Nodes, it replaces the existing
"Combine RGBA/HSVA/YCbCrA/YUVA" and "Separate RGBA/HSVA/YCbCrA/YUVA"
nodes.
- Within Texture Nodes, it replaces the existing "Combine RGBA" and
"Separate RGBA" nodes.
- Within Shader Nodes, it replaces the existing "Combine RGB/HSV" and
"Separate RGB/HSV" nodes.
Python addons have not been updated to the new nodes yet.
**New shader code**
In node_color.h, color.h and gpu_shader_material_color_util.glsl,
missing methods hsl_to_rgb and rgb_to_hsl are added by directly
converting existing C code. They always produce the same result.
**Old code**
As requested by T96219, old nodes still exist but are not displayed in
the add menu. This means Python scripts can still create them as usual.
Otherwise, versioning replaces the old nodes with the new nodes when
opening .blend files.
Differential Revision: https://developer.blender.org/D14034
Keep the existing Rec.709 fit and convert to other colorspace if needed, it
seems accurate enough in practice, and keeps the same performance for the
default case.
Propagate the fp settings from the main thread to all the worker threads (the fp settings includes the FZ settings among other things) - this guarantees consistency in execution of floating point math regardless if its executed in tbb thread arena or on main thread
Add FZ mode to arm64/aarch64 in parallel to the way its been done on intel processors, currently compiling for arm target does not set this mode at all, hence potentially runs slower and with possible results mismatch with intel x86.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D14454
* Add missing GLEW and hgiGL libraries for Hydra
* Fix wrong case sensitive include
* Fix link errors by adding external libs to static Hydra lib
* Work around weird Hydra link error with MAX_SAMPLES
* Use Embree by default for Hydra
* Sync external libs code with standalone
* Update version number to match Blender
* Remove unneeded CLEW/GLEW from test executable
None of this should affect Cycles in Blender.
Ref T96731
This adds support for selective rendering of caustics in shadows of refractive
objects. Example uses are rendering of underwater caustics and eye caustics.
This is based on "Manifold Next Event Estimation", a method developed for
production rendering. The idea is to selectively enable shadow caustics on a
few objects in the scene where they have a big visual impact, without impacting
render performance for the rest of the scene.
The Shadow Caustic option must be manually enabled on light, caustic receiver
and caster objects. For such light paths, the Filter Glossy option will be
ignored and replaced by sharp caustics.
Currently this method has a various limitations:
* Only caustics in shadows of refractive objects work, which means no caustics
from reflection or caustics that outside shadows. Only up to 4 refractive
caustic bounces are supported.
* Caustic caster objects should have smooth normals.
* Not currently support for Metal GPU rendering.
In the future this method may be extended for more general caustics.
TECHNICAL DETAILS
This code adds manifold next event estimation through refractive surface(s) as a
new sampling technique for direct lighting, i.e. finding the point on the
refractive surface(s) along the path to a light sample, which satisfies Fermat's
principle for a given microfacet normal and the path's end points. This
technique involves walking on the "specular manifold" using a pseudo newton
solver. Such a manifold is defined by the specular constraint matrix from the
manifold exploration framework [2]. For each refractive interface, this
constraint is defined by enforcing that the generalized half-vector projection
onto the interface local tangent plane is null. The newton solver guides the
walk by linearizing the manifold locally before reprojecting the linear solution
onto the refractive surface. See paper [1] for more details about the technique
itself and [3] for the half-vector light transport formulation, from which it is
derived.
[1] Manifold Next Event Estimation
Johannes Hanika, Marc Droske, and Luca Fascione. 2015.
Comput. Graph. Forum 34, 4 (July 2015), 87–97.
https://jo.dreggn.org/home/2015_mnee.pdf
[2] Manifold exploration: a Markov Chain Monte Carlo technique for rendering
scenes with difficult specular transport Wenzel Jakob and Steve Marschner.
2012. ACM Trans. Graph. 31, 4, Article 58 (July 2012), 13 pages.
https://www.cs.cornell.edu/projects/manifolds-sg12/
[3] The Natural-Constraint Representation of the Path Space for Efficient
Light Transport Simulation. Anton S. Kaplanyan, Johannes Hanika, and Carsten
Dachsbacher. 2014. ACM Trans. Graph. 33, 4, Article 102 (July 2014), 13 pages.
https://cg.ivd.kit.edu/english/HSLT.php
The code for this samping technique was inserted at the light sampling stage
(direct lighting). If the walk is successful, it turns off path regularization
using a specialized flag in the path state (PATH_MNEE_SUCCESS). This flag tells
the integrator not to blur the brdf roughness further down the path (in a child
ray created from BSDF sampling). In addition, using a cascading mechanism of
flag values, we cull connections to caustic lights for this and children rays,
which should be resolved through MNEE.
This mechanism also cancels the MIS bsdf counter part at the casutic receiver
depth, in essence leaving MNEE as the only sampling technique from receivers
through refractive casters to caustic lights. This choice might not be optimal
when the light gets large wrt to the receiver, though this is usually not when
you want to use MNEE.
This connection culling strategy removes a fair amount of fireflies, at the cost
of introducing a slight bias. Because of the selective nature of the culling
mechanism, reflective caustics still benefit from the native path
regularization, which further removes fireflies on other surfaces (bouncing
light off casters).
Differential Revision: https://developer.blender.org/D13533
