For example
```
OIIOOutputDriver::~OIIOOutputDriver()
{
}
```
becomes
```
OIIOOutputDriver::~OIIOOutputDriver() {}
```
Saves quite some vertical space, which is especially handy for
constructors.
Pull Request: https://projects.blender.org/blender/blender/pulls/105594
The name #ensure_valid_reflection seems to indicate that the resulted
reflection must be valid, whereas in the reality it only ensure validity
for specular reflections. The new name matches the behavior better.
This function checks if the shading normal would result in an invalid reflection into the lower hemisphere; if it is the case, the function raises the shading normal just enough so that the specular reflection lies above the surface. This is a trick to prevent dark regions at grazing angles caused by normal/bump maps. However, the specular direction is not a good representation for a diffuse material, applying this function sometimes brightens the result too much and causes unexpected results. This patch applies the function to only glossy materials instead.
Pull Request: #105776
Actually both potential roots lie in the interval [0, 1], so the
function ended up checking both roots all the time.
The new implementation explains why only one of the roots is valid; it
saves two square roots and a bunch of other computations.
This commit implements three OSL microfacet closures that are needed to support
MaterialX: dielectric_bsdf, conductor_bsdf and generalized_schlick_bsdf.
Internally these map to existing microfacet closures, only the Fresnel term is
different.
Currently, we use the closure type to encode the type of microfacet distribution
(GGX/Beckmann/Sharp/MultiGGX), the lobes we're interested in
(Reflection/Refraction/both) AND the Fresnel type (None or Principled v1).
This results in the mess of dozens of options that we currently have. Since
adding Principled v2 and the MaterialX OSL closures will involve adding more
Fresnel types, this clearly doesn't scale.
But, since the earlier Fresnel rework (D17101), the Fresnel type only matters
in one place now. This allows to significantly clean up the closure type
handling. To do this, MicrofacetBsdfs now separately store their Fresnel type,
and instead of a single MicrofacetExtra we have one struct per Fresnel type
(unless no extra data is needed).
Further, instead of having one _setup() function per combination, the Fresnel
setup is also split into separate functions. This decouples the implementation
of new Fresnel terms from most of the Microfacet logic, and makes it a very
simple and clean operation.
This commit replaces the current Glass approach, where Glass is a virtual closure
that gets replaced with a Glossy and a Refractive closure, with a combined
closure that handles Fresnel after sampling the microfacet. That way, the Fresnel
term is more accurate since it accounts for the microfacet normal, not the
shading normal.
Also updates the BSDF sampling to use a 3D sampler now, since we need two
dimensions to pick the microfacet normal and then a third dimension to pick
reflection/refraction. This can also be used to get rid of the LCG in the
Principled Hair BSDF, which means we can remove it altogether once MultiGGX is
gone.
Also, "sharp" is now supported as a microfacet distribution in OSL, and 2
is supported as the "refract" argument to microfacet() in order to get glass.
The proper fix (bb9eb262d4) caused compilation problems with HIP, so we're
delaying it until 3.6.
To fix the original bug report (#104586), this is a quick workaround that'll
hopefully not upset the compiler.
Pull Request #104723
- Rename roughness variables for more clarity - before, the SVM/OSL code would
set s and v to the linear roughness values, and the setup function would over-
write them with the distribution parameters. This actually caused a bug in the
albedo code, since it intended to use the linear roughness value, but ended up
getting the remapped value.
- Deduplicate the evaluation and sample functions. Most of their code is the
same, only the middle part is different.
- Changed albedo computation to return the sum of the intensities of the four
BSDF lobes. Previously, the code applied the inverse of the color->sigma
mapping from the paper - this returns the color specified in the node, but
for very dark hair (e.g. when using the Melanin controls) the result is
extremely low (e.g. 0.000001) despite the hair still reflecting a significant
amount of light (since the R lobe is independent of sigma). This causes issues
with the light component passes, so this change fixes#104586.
- There's quite a few computations at the start of the evaluation function that
are needed for sampling, evaluation and albedo computation, but only depend on
the view direction. Therefore, just precompute them - we still have space in
PrincipledHairExtra after all.
- Fix a tiny bug - the direction sampling code did not account for the R lobe
roughness modifier.
Pull Request #104669
This is both a cleanup and a preparation for the Principled v2 changes.
Notable changes:
- Clearcoat weight is now folded into the closure weight, there's no reason
to track this separately.
- There's a general-purpose helper for computing a Closure's albedo, which is
currently used by the denoising albedo and diffuse/gloss/transmission color
passes.
- The d/g/t color passes didn't account for closure albedo before, this means
that e.g. metallic shaders with Principled v2 now have their color texture
included in the glossy color pass. Also fixes T104041 (sheen albedo).
- Instead of precomputing and storing the albedo during shader setup, compute
it when needed. This is technically redundant since we still need to compute
it on shader setup to adjust the sample weight, but the operation is cheap
enough that freeing up the storage seems worth it.
- Future changes (Principled v2) are easier to integrate since the Fresnel
handling isn't all over the place anymore.
- Fresnel handling in the Multiscattering GGX code is still ugly, but since
removing that entirely is the next step, putting effort into cleaning it up
doesn't seem worth it.
- Apart from the d/g/t color passes, no changes to render results are expected.
Differential Revision: https://developer.blender.org/D17101
Based on "Sampling the GGX Distribution of Visible Normals" by Eric Heitz
(https://jcgt.org/published/0007/04/01/).
Also, this removes the lambdaI computation from the Beckmann sampling code and
just recomputes it below. We already need to recompute for two other cases
(GGX and clearcoat), so this makes the code more consistent.
In terms of performance, I don't expect a notable impact since the earlier
computation also was non-trivial, and while it probably was slightly more
accurate, I'd argue that being consistent between evaluation and sampling is
more important than absolute numerical accuracy anyways.
Differential Revision: https://developer.blender.org/D17100
This gives closer results to what I've seen in papers and other renderers when
using the code to precompute albedo later (to replace MultiGGX).
It's usually a tiny difference, the only case where I've seen it matter is
in the `shader/node_group_float.blend` test - but that's a (single-scatter) GGX
closure with 0.9 roughness, so it's not too surprising. In any case, the new
result looks closer to Eevee, so that's good I guess.
Differential Revision: https://developer.blender.org/D17099
The lookup table method on CPU and the numerical root finding method on
GPU give quite different results. This commit deletes the Beckmann lookup
table and uses numerical root finding on all devices. For the numerical
root finding, a combined bisection-Newton method with precision control
is used.
Differential Revision: https://developer.blender.org/D17050
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.
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
This patch generalizes the OSL support in Cycles to include GPU
device types and adds an implementation for that in the OptiX
device. There are some caveats still, including simplified texturing
due to lack of OIIO on the GPU and a few missing OSL intrinsics.
Note that this is incomplete and missing an update to the OSL
library before being enabled! The implementation is already
committed now to simplify further development.
Maniphest Tasks: T101222
Differential Revision: https://developer.blender.org/D15902
Simplifies code overall to do it inside the eval function, most of the BSDFs
already compute the dot product.
The refactoring in bsdf_principled_hair_eval() was needed to avoid a HIP
compiler bug. Cause is unclear, just changing the implementation enough
is meant to sidestep it.
Ref T92571, D15286
* Return roughness and IOR for BSDF sampling
* Add functions to query IOR and label for given BSDF
* Default IOR to 1.0 instead of 0.0 for BSDFs that don't use it
* Ensure pdf >= 0.0 in case of numerical precision issues
Ref T92571, D15286
Cleans up the file structure to be more similar to that of the SVM
and also makes it possible to build kernels with OSL support, but
without having to include SVM support.
This patch was split from D15902.
Differential Revision: https://developer.blender.org/D15949
This has the advantage of being able to use information about the
existing OSL closures in various places without code duplication. In
addition, the setup code for all closures was moved to standalone
functions to avoid usage of virtual function calls in preparation for GPU
support.
This patch was split from D15902.
Differential Revision: https://developer.blender.org/D15917
* Store compact ray differentials in ShaderData and compute full differentials
on demand. This reduces register pressure on the GPU.
* Remove BSDF differential code that was effectively doing nothing as the
differential orientation was discarded when making it compact.
This gives a 1-5% speedup with RTX A6000 + OptiX in our benchmarks, with the
bigger speedups in simpler scenes.
Renders appear to be identical except for the Both displacement option that
does both displacement and bump.
Differential Revision: https://developer.blender.org/D15677
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
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 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
* 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.
The Multiscatter GGX code was missing the same-side checks for incoming and
outgoing directions w.r.t. to shading and geometry normal.
Should not be needed for the Glass variant since it intentionally has both
reflection and transmission.
Currently, the `eval` and `pdf` are not explicitly set to zero when a BSDF sample is invalid (e.g., below the upper hemisphere), when calling
`bsdf_sample` or `bsdf_eval`. It is assumed that `eval` and `pdf` are set to zero before these functions are called, which can cause problems if not.
This patch fixes this potential problem by explicitly setting `eval` and `pdf` to zero when the sampled direction is invalid.
I also added a sanity check if `eval` and `pdf` are valid (i.e., >= 0.f).
The check is activated when build in debug mode and with the `WITH_CYCLES_DEBUG` set to `ON`.
Reviewed By: brecht, sergey
Differential Revision: https://developer.blender.org/D14776
