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Bugfix: jitterd particle distribution was really slow for a large

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number of particles/face. Now for > 25 particles/face it switches
to using a QMC hammersley distribution, much faster, for less
jitter still looks a bit better.
This commit is contained in:
Brecht Van Lommel
2008-02-28 13:31:25 +00:00
parent 97517528d4
commit 6af5a98c7e
1 changed files with 31 additions and 2 deletions
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33
source/blender/blenkernel/intern/particle_system.c
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@@ -408,6 +408,29 @@ static void distribute_particles_in_grid(DerivedMesh *dm, ParticleSystem *psys)
}
}
/* 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 = rng_new(31415926 + n + seed);
offs[0]= rng_getDouble(rng) + amount;
offs[1]= rng_getDouble(rng) + amount;
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);
}
}
/* modified copy from effect.c */
static void init_mv_jit(float *jit, int num, int seed2, float amount)
{
@@ -1213,9 +1236,15 @@ int psys_threads_init_distribution(ParticleThread *threads, DerivedMesh *finaldm
//if(jitlevel>100) jitlevel= 100;
}
jit= MEM_callocN(2+ jitlevel*2*sizeof(float), "jit");
jit= MEM_callocN((2+ jitlevel*2)*sizeof(float), "jit");
init_mv_jit(jit, jitlevel, psys->seed, part->jitfac);
/* for small amounts of particles we use regular jitter since it looks
* a bit better, for larger amounts we switch to hammersley sequence
* because it is much faster */
if(jitlevel < 25)
init_mv_jit(jit, jitlevel, psys->seed, part->jitfac);
else
hammersley_create(jit, jitlevel+1, psys->seed, part->jitfac);
BLI_array_randomize(jit, 2*sizeof(float), jitlevel, psys->seed); /* for custom jit or even distribution */
}