diff options
author | Brecht Van Lommel <brecht@blender.org> | 2021-10-08 20:44:56 +0300 |
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committer | Brecht Van Lommel <brecht@blender.org> | 2021-10-11 19:22:54 +0300 |
commit | a94343a8afcac5d6db09c8461e67ad1ba5a85d35 (patch) | |
tree | f56b8e6a956ca87f25b01f94b6f6421636448402 /intern/cycles/kernel/kernel_types.h | |
parent | 73a05ff9e83a31be34d32a92cd5fb4d17994e342 (diff) |
Cycles: improve SSS Fresnel and retro-reflection in Principled BSDF
For details see the "Extending the Disney BRDF to a BSDF with Integrated
Subsurface Scattering" paper.
We split the diffuse BSDF into a lambertian and retro-reflection component.
The retro-reflection component is always handled as a BSDF, while the
lambertian component can be replaced by a BSSRDF.
For the BSSRDF case, we compute Fresnel separately at the entry and exit
points, which may have different normals. As the scattering radius decreases
this converges to the BSDF case.
A downside is that this increases noise for subsurface scattering in the
Principled BSDF, due to some samples going to the retro-reflection component.
However the previous logic (also in 2.93) was simple wrong, using a
non-sensical view direction vector at the exit point. We use an importance
sampling weight estimate for the retro-reflection to try to better balance
samples between the BSDF and BSSRDF.
Differential Revision: https://developer.blender.org/D12801
Diffstat (limited to 'intern/cycles/kernel/kernel_types.h')
-rw-r--r-- | intern/cycles/kernel/kernel_types.h | 20 |
1 files changed, 11 insertions, 9 deletions
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h index eb681683d6a..00457695e53 100644 --- a/intern/cycles/kernel/kernel_types.h +++ b/intern/cycles/kernel/kernel_types.h @@ -263,32 +263,34 @@ enum PathRayFlag { /* Perform subsurface scattering. */ PATH_RAY_SUBSURFACE_RANDOM_WALK = (1 << 20), PATH_RAY_SUBSURFACE_DISK = (1 << 21), - PATH_RAY_SUBSURFACE = (PATH_RAY_SUBSURFACE_RANDOM_WALK | PATH_RAY_SUBSURFACE_DISK), + PATH_RAY_SUBSURFACE_USE_FRESNEL = (1 << 22), + PATH_RAY_SUBSURFACE = (PATH_RAY_SUBSURFACE_RANDOM_WALK | PATH_RAY_SUBSURFACE_DISK | + PATH_RAY_SUBSURFACE_USE_FRESNEL), /* Contribute to denoising features. */ - PATH_RAY_DENOISING_FEATURES = (1 << 22), + PATH_RAY_DENOISING_FEATURES = (1 << 23), /* Render pass categories. */ - PATH_RAY_REFLECT_PASS = (1 << 23), - PATH_RAY_TRANSMISSION_PASS = (1 << 24), - PATH_RAY_VOLUME_PASS = (1 << 25), + PATH_RAY_REFLECT_PASS = (1 << 24), + PATH_RAY_TRANSMISSION_PASS = (1 << 25), + PATH_RAY_VOLUME_PASS = (1 << 26), PATH_RAY_ANY_PASS = (PATH_RAY_REFLECT_PASS | PATH_RAY_TRANSMISSION_PASS | PATH_RAY_VOLUME_PASS), /* Shadow ray is for a light or surface. */ - PATH_RAY_SHADOW_FOR_LIGHT = (1 << 26), + PATH_RAY_SHADOW_FOR_LIGHT = (1 << 27), /* A shadow catcher object was hit and the path was split into two. */ - PATH_RAY_SHADOW_CATCHER_HIT = (1 << 27), + PATH_RAY_SHADOW_CATCHER_HIT = (1 << 28), /* A shadow catcher object was hit and this path traces only shadow catchers, writing them into * their dedicated pass for later division. * * NOTE: Is not covered with `PATH_RAY_ANY_PASS` because shadow catcher does special handling * which is separate from the light passes. */ - PATH_RAY_SHADOW_CATCHER_PASS = (1 << 28), + PATH_RAY_SHADOW_CATCHER_PASS = (1 << 29), /* Path is evaluating background for an approximate shadow catcher with non-transparent film. */ - PATH_RAY_SHADOW_CATCHER_BACKGROUND = (1 << 29), + PATH_RAY_SHADOW_CATCHER_BACKGROUND = (1 << 30), }; /* Configure ray visibility bits for rays and objects respectively, |