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Diffstat (limited to 'intern/cycles/kernel/kernel_jitter.h')
| -rw-r--r-- | intern/cycles/kernel/kernel_jitter.h | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/intern/cycles/kernel/kernel_jitter.h b/intern/cycles/kernel/kernel_jitter.h new file mode 100644 index 00000000000..5ea44cd0cad --- /dev/null +++ b/intern/cycles/kernel/kernel_jitter.h @@ -0,0 +1,181 @@ +/* + * Copyright 2013, Blender Foundation. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +CCL_NAMESPACE_BEGIN + +/* "Correlated Multi-Jittered Sampling" + * Andrew Kensler, Pixar Technical Memo 13-01, 2013 */ + +/* todo: find good value, suggested 64 gives pattern on cornell box ceiling */ +#define CMJ_RANDOM_OFFSET_LIMIT 4096 + +__device_inline bool cmj_is_pow2(int i) +{ + return (i & (i - 1)) == 0; +} + +__device_inline int cmj_fast_mod_pow2(int a, int b) +{ + return (a & (b - 1)); +} + +/* a must be > 0 and b must be > 1 */ +__device_inline int cmj_fast_div_pow2(int a, int b) +{ +#ifdef __KERNEL_SSE2__ + return a >> __builtin_ctz(b); +#else + return a/b; +#endif +} + +__device_inline uint cmj_w_mask(uint w) +{ +#ifdef __KERNEL_SSE2__ + return ((1 << (32 - __builtin_clz(w))) - 1); +#else + w |= w >> 1; + w |= w >> 2; + w |= w >> 4; + w |= w >> 8; + w |= w >> 16; + + return w; +#endif +} + +__device_inline uint cmj_permute(uint i, uint l, uint p) +{ + uint w = l - 1; + + if((l & w) == 0) { + /* l is a power of two (fast) */ + i ^= p; + i *= 0xe170893d; + i ^= p >> 16; + i ^= (i & w) >> 4; + i ^= p >> 8; + i *= 0x0929eb3f; + i ^= p >> 23; + i ^= (i & w) >> 1; + i *= 1 | p >> 27; + i *= 0x6935fa69; + i ^= (i & w) >> 11; + i *= 0x74dcb303; + i ^= (i & w) >> 2; + i *= 0x9e501cc3; + i ^= (i & w) >> 2; + i *= 0xc860a3df; + i &= w; + i ^= i >> 5; + + return (i + p) & w; + } + else { + /* l is not a power of two (slow) */ + w = cmj_w_mask(w); + + do { + i ^= p; + i *= 0xe170893d; + i ^= p >> 16; + i ^= (i & w) >> 4; + i ^= p >> 8; + i *= 0x0929eb3f; + i ^= p >> 23; + i ^= (i & w) >> 1; + i *= 1 | p >> 27; + i *= 0x6935fa69; + i ^= (i & w) >> 11; + i *= 0x74dcb303; + i ^= (i & w) >> 2; + i *= 0x9e501cc3; + i ^= (i & w) >> 2; + i *= 0xc860a3df; + i &= w; + i ^= i >> 5; + } while (i >= l); + + return (i + p) % l; + } +} + +__device_inline uint cmj_hash(uint i, uint p) +{ + i ^= p; + i ^= i >> 17; + i ^= i >> 10; + i *= 0xb36534e5; + i ^= i >> 12; + i ^= i >> 21; + i *= 0x93fc4795; + i ^= 0xdf6e307f; + i ^= i >> 17; + i *= 1 | p >> 18; + + return i; +} + +__device_inline float cmj_randfloat(uint i, uint p) +{ + return cmj_hash(i, p) * (1.0f / 4294967808.0f); +} + +#ifdef __CMJ__ +__device_noinline float cmj_sample_1D(int s, int N, int p) +{ + uint x = cmj_permute(s, N, p * 0x68bc21eb); + float jx = cmj_randfloat(s, p * 0x967a889b); + + float invN = 1.0f/N; + return (x + jx)*invN; +} + +__device_noinline float2 cmj_sample_2D(int s, int N, int p) +{ + int m = float_to_int(sqrtf(N)); + int n = (N + m - 1)/m; + float invN = 1.0f/N; + float invm = 1.0f/m; + float invn = 1.0f/n; + + s = cmj_permute(s, N, p * 0x51633e2d); + + int sdivm, smodm; + + if(cmj_is_pow2(m)) { + sdivm = cmj_fast_div_pow2(s, m); + smodm = cmj_fast_mod_pow2(s, m); + } + else { + sdivm = float_to_int(s * invm); + smodm = s - sdivm*m; + } + + uint sx = cmj_permute(smodm, m, p * 0x68bc21eb); + uint sy = cmj_permute(sdivm, n, p * 0x02e5be93); + + float jx = cmj_randfloat(s, p * 0x967a889b); + float jy = cmj_randfloat(s, p * 0x368cc8b7); + + return make_float2((sx + (sy + jx)*invn)*invm, (s + jy)*invN); +} +#endif + +CCL_NAMESPACE_END + |