blender
/
blender
129
398
Fork 572
Code Issues 6.2k Pull Requests 752 Projects 19 Wiki Activity

Cycles: Improve sampling of area lights 

This patch uses the sampling method described in "A Low Distortion Map Between Triangle and Square" by Eric Heitz.
The benefit is avoiding sqrt in the calculation, which could be cheaper on some architectures, and the result is
more even sampling across the triangle surface.

Based on ideas from
https://pharr.org/matt/blog/2019/02/27/triangle-sampling-1.html
https://pharr.org/matt/blog/2019/03/13/triangle-sampling-1.5.html

Reviewed By: Brecht Van Lommel

Differential Revision: https://developer.blender.org/D6566
This commit is contained in:
Antonis Ryakiotakis 2020-05-23 14:21:49 +02:00
parent 86fa8dc7f7
commit 08c1f5bf33
1 changed files with 12 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
intern/cycles/kernel/kernel_light.h
View File

@ -1041,11 +1041,19 @@ ccl_device_forceinline void triangle_light_sample(KernelGlobals *kg,
}
}
else {
/* compute random point in triangle */
randu = sqrtf(randu);
/* compute random point in triangle. From Eric Heitz's "A Low-Distortion Map Between Triangle
* and Square" */
float u = randu;
float v = randv;
if (v > u) {
u *= 0.5f;
v -= u;
}
else {
v *= 0.5f;
u -= v;
}
const float u = 1.0f - randu;
const float v = randv * randu;
const float t = 1.0f - u - v;
ls->P = u * V[0] + v * V[1] + t * V[2];
/* compute incoming direction, distance and pdf */