Commit Graph

16 Commits

Author SHA1 Message Date
Sergey Sharybin
ad26407b52 Cycles: Implement approximate reflectance profiles
Using this paper:

  http://graphics.pixar.com/library/ApproxBSSRDF/paper.pdf

This model gives less blurry results than the Cubic and Gaussian
we had implemented:

- Cubic: https://developer.blender.org/F279670
- Burley: https://developer.blender.org/F279671

The model is called "Christensen-Burley" in the interface, which
actually should be read as "Physically based" or "Realistic".

Reviewers: juicyfruit, dingto, lukasstockner97, brecht

Reviewed By: brecht, dingto

Subscribers: robocyte

Differential Revision: https://developer.blender.org/D1759
2016-02-04 13:27:23 +05:00
Sergey Sharybin
e42852a339 Cycles: Cleanup and reference actual paper used for BSSRDF sampling 2016-02-02 18:06:29 +01:00
Sergey Sharybin
ae7d84dbc1 Cycles: Use native saturate function for CUDA
This more a workaround for CUDA optimizer which can't optimize clamp(x, 0, 1)
into a single instruction and uses 4 instructions instead.

Original patch by @lockal with own modification:

  Don't make changes outside of the kernel. They don't make any difference
  anyway and term saturate() has a bit different meaning outside of kernel.

This gives around 2% of speedup in Barcelona file, but in more complex shader
setups with lots of math nodes with clamping speedup could be much nicer.

Subscribers: dingto

Projects: #cycles

Differential Revision: https://developer.blender.org/D1224
2015-04-28 00:38:32 +05:00
Sergey Sharybin
5ff132182d Cycles: Code cleanup, spaces around keywords
This inconsistency drove me totally crazy, it's really confusing
when it's inconsistent especially when you work on both Cycles and
Blender sides.

Shouldn;t cause merge PITA, it's whitespace changes only, Git should
be able to merge it nicely.
2015-03-28 00:15:15 +05:00
Sergey Sharybin
87cff57207 Fix T44123: Cycles SSS renders black in recent builds
Issue was introduced in 01ee21f where i didn't notice *_setup()
function only doing partial initialization, and some of parameters
are expected to be initialized by callee function.

This was hitting only some setups, so tests with benchmark scenes
didn't unleash issues. Now it should all be fine.

This is to go to the 2.74 branch and we actually might re-AHOY.
2015-03-25 02:33:49 +05:00
Sergey Sharybin
ed7e593a4b Fix T43926: Volume scatter: intersecting objects GPU rendering artifacts
Fix T44007: Cycles Volumetrics: block artifacts with overlapping volumes

The issue was caused by uninitialized parameters of some closures, which
lead to unpredictable behavior of shader_merge_closures().
2015-03-23 12:48:33 +05:00
Thomas Dinges
ee36e75b85 Cleanup: Fix Cycles Apache header.
This was already mixed a bit, but the dot belongs there.
2014-12-25 02:50:24 +01:00
c18712e868 Cycles: change __device and similar qualifiers to ccl_device in kernel code.
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.
2013-11-18 08:48:15 +01:00
Brecht Van Lommel
b314209356 Cycles: add a sharpness input to the Cubic SSS falloff. When set to 1 this will
give a result more similar to the Compatible falloff option. The scale is x2
though to keep the perceived scatter radius roughly the same while changing the
sharpness. Difference with compatible will be mainly on non-flat geometry.
2013-09-03 22:39:17 +00:00
Brecht Van Lommel
841fe45df9 Cycles: change Gaussian subsurface scattering falloff to be more similar to
the Cubic falloff, see here for details.
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#Subsurface_Scattering
2013-08-28 19:22:46 +00:00
Brecht Van Lommel
b9ce231060 Cycles: relicense GNU GPL source code to Apache version 2.0.
More information in this post:
http://code.blender.org/

Thanks to all contributes for giving their permission!
2013-08-18 14:16:15 +00:00
Brecht Van Lommel
d43682d51b Cycles: Subsurface Scattering
New features:

* Bump mapping now works with SSS
* Texture Blur factor for SSS, see the documentation for details:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#Subsurface_Scattering

Work in progress for feedback:

Initial implementation of the "BSSRDF Importance Sampling" paper, which uses
a different importance sampling method. It gives better quality results in
many ways, with the availability of both Cubic and Gaussian falloff functions,
but also tends to be more noisy when using the progressive integrator and does
not give great results with some geometry. It works quite well for the
non-progressive integrator and is often less noisy there.

This code may still change a lot, so unless you're testing it may be best to
stick to the Compatible falloff function.

Skin test render and file that takes advantage of the gaussian falloff:
http://www.pasteall.org/pic/show.php?id=57661
http://www.pasteall.org/pic/show.php?id=57662
http://www.pasteall.org/blend/23501
2013-08-18 14:15:57 +00:00
Brecht Van Lommel
d835d2f4e6 Code cleanup: avoid some warnings due to implicit uint/int/float/double conversion. 2013-06-07 16:06:17 +00:00
Thomas Dinges
8e487bebd3 Cycles / BSSRDF:
* Avoid one max() call for the bssrdf radius, the if condition already checks for values < BSSRDF_MIN_RADIUS.
2013-05-16 18:39:45 +00:00
Thomas Dinges
7636aeffe1 Cycles / Math:
* Add M_2PI_F and M_4PI_F constants and use them inside the codebase.
2013-05-12 14:13:29 +00:00
Brecht Van Lommel
de9dffc61e Cycles: initial subsurface multiple scattering support. It's not working as
well as I would like, but it works, just add a subsurface scattering node and
you can use it like any other BSDF.

It is using fully raytraced sampling compatible with progressive rendering
and other more advanced rendering algorithms we might used in the future, and
it uses no extra memory so it's suitable for complex scenes.

Disadvantage is that it can be quite noisy and slow. Two limitations that will
be solved are that it does not work with bump mapping yet, and that the falloff
function used is a simple cubic function, it's not using the real BSSRDF
falloff function yet.

The node has a color input, along with a scattering radius for each RGB color
channel along with an overall scale factor for the radii.

There is also no GPU support yet, will test if I can get that working later.

Node Documentation:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#BSSRDF

Implementation notes:
http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/Subsurface_Scattering
2013-04-01 20:26:52 +00:00