void BLI_jitter_init(float (*jitarr)[2], int num) { float (*jit2)[2]; float num_fl, num_fl_sqrt; float x, rad1, rad2, rad3; RNG *rng; int i; if (num == 0) { return; } num_fl = (float)num; num_fl_sqrt = sqrtf(num_fl); jit2 = MEM_mallocN(12 + (unsigned int)num * sizeof(float[2]), "initjit"); rad1 = 1.0f / num_fl_sqrt; rad2 = 1.0f / num_fl; rad3 = num_fl_sqrt / num_fl; rng = BLI_rng_new(31415926 + (unsigned int)num); x = 0; for (i = 0; i < num; i++) { jitarr[i][0] = x + rad1 * (float)(0.5 - BLI_rng_get_double(rng)); jitarr[i][1] = (float)i / num_fl + rad1 * (float)(0.5 - BLI_rng_get_double(rng)); x += rad3; x -= floorf(x); } BLI_rng_free(rng); for (i = 0; i < 24; i++) { BLI_jitterate1(jitarr, jit2, num, rad1); BLI_jitterate1(jitarr, jit2, num, rad1); BLI_jitterate2(jitarr, jit2, num, rad2); } MEM_freeN(jit2); /* finally, move jittertab to be centered around (0, 0) */ for (i = 0; i < num; i++) { jitarr[i][0] -= 0.5f; jitarr[i][1] -= 0.5f; } }
/* modified copy from rayshade.c */ static void hammersley_create(float *out, int n, int seed, float amount) { RNG *rng; double p, t, offs[2]; int k, kk; rng = BLI_rng_new(31415926 + n + seed); offs[0] = BLI_rng_get_double(rng) + (double)amount; offs[1] = BLI_rng_get_double(rng) + (double)amount; BLI_rng_free(rng); for (k = 0; k < n; k++) { t = 0; for (p = 0.5, kk = k; kk; p *= 0.5, kk >>= 1) if (kk & 1) /* kk mod 2 = 1 */ t += p; out[2*k + 0] = fmod((double)k/(double)n + offs[0], 1.0); out[2*k + 1] = fmod(t + offs[1], 1.0); } }