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Use a more naive RNG for the lightmapper 

This speeds up the lightmapper by about 10% with no visible impact. A
comparison is up here:

https://tmm.cx/nextcloud/s/Log1eAXen1dJzBz

AMD Ryzen 7 1700 Eight-Core Processor
Sponza scene

pcg32
256/256/high   00:10:13
256/256/medium 00:02:50
256/256/low    00:01:11

xorshift
256/256/high   00:09:32
256/256/medium 00:02:34
256/256/low    00:01:05
This commit is contained in:
Hein-Pieter van Braam 2017-12-17 00:05:13 +01:00
parent 83291eab3a
commit be4448bd1f
1 changed files with 14 additions and 2 deletions
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16
scene/3d/voxel_light_baker.cpp
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@ -1614,6 +1614,18 @@ Vector3 VoxelLightBaker::_compute_pixel_light_at_pos(const Vector3 &p_pos, const
return accum;
}
uint32_t xorshiftstate[] = { 123 }; // anything non-zero will do here
_ALWAYS_INLINE_ uint32_t xorshift32() {
/* Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs" */
uint32_t x = xorshiftstate[0];
x ^= x << 13;
x ^= x >> 17;
x ^= x << 5;
xorshiftstate[0] = x;
return x;
}
Vector3 VoxelLightBaker::_compute_ray_trace_at_pos(const Vector3 &p_pos, const Vector3 &p_normal) {
int samples_per_quality[3] = { 48, 128, 512 };
@ -1638,9 +1650,9 @@ Vector3 VoxelLightBaker::_compute_ray_trace_at_pos(const Vector3 &p_pos, const V
for (int i = 0; i < samples; i++) {
float random_angle1 = (((Math::rand() % 65535) / 65535.0) * 2.0 - 1.0) * spread;
float random_angle1 = (((xorshift32() % 65535) / 65535.0) * 2.0 - 1.0) * spread;
Vector3 axis(0, sin(random_angle1), cos(random_angle1));
float random_angle2 = ((Math::rand() % 65535) / 65535.0) * Math_PI * 2.0;
float random_angle2 = ((xorshift32() % 65535) / 65535.0) * Math_PI * 2.0;
Basis rot(Vector3(0, 0, 1), random_angle2);
axis = rot.xform(axis);