diff options
Diffstat (limited to 'intern/cycles/kernel/sample/pattern.h')
| -rw-r--r-- | intern/cycles/kernel/sample/pattern.h | 37 |
1 files changed, 26 insertions, 11 deletions
diff --git a/intern/cycles/kernel/sample/pattern.h b/intern/cycles/kernel/sample/pattern.h index 6477e29fa40..ebdecc1bff9 100644 --- a/intern/cycles/kernel/sample/pattern.h +++ b/intern/cycles/kernel/sample/pattern.h @@ -90,18 +90,33 @@ ccl_device_inline uint path_rng_hash_init(KernelGlobals kg, return rng_hash; } -ccl_device_inline bool sample_is_even(int pattern, int sample) +/** + * Splits samples into two different classes, A and B, which can be + * compared for variance estimation. + */ +ccl_device_inline bool sample_is_class_A(int pattern, int sample) { - if (pattern == SAMPLING_PATTERN_PMJ) { - /* See Section 10.2.1, "Progressive Multi-Jittered Sample Sequences", Christensen et al. - * We can use this to get divide sample sequence into two classes for easier variance - * estimation. */ - return popcount(uint(sample) & 0xaaaaaaaa) & 1; - } - else { - /* TODO(Stefan): Are there reliable ways of dividing Sobol-Burley into two classes? */ - return sample & 0x1; +#if 0 + if (!(pattern == SAMPLING_PATTERN_PMJ || pattern == SAMPLING_PATTERN_SOBOL_BURLEY)) { + /* Fallback: assign samples randomly. + * This is guaranteed to work "okay" for any sampler, but isn't good. + * (Note: the seed constant is just a random number to guard against + * possible interactions with other uses of the hash. There's nothing + * special about it.) + */ + return hash_hp_seeded_uint(sample, 0xa771f873) & 1; } -} +#else + (void)pattern; +#endif + /* This follows the approach from section 10.2.1 of "Progressive + * Multi-Jittered Sample Sequences" by Christensen et al., but + * implemented with efficient bit-fiddling. + * + * This approach also turns out to work equally well with Sobol-Burley + * (see https://developer.blender.org/D15746#429471). + */ + return popcount(uint(sample) & 0xaaaaaaaa) & 1; +} CCL_NAMESPACE_END |