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Cleanup a bit particle distribution code. 

Also do proper intial/final checks to avoid adding particle on zero-weight extreme items,
instead of using cheap tricks like 'small offset'...
This commit is contained in:
Bastien Montagne 2016-04-09 22:42:52 +02:00
parent 950acb0ced
commit 019ce363b0
Notes: blender-bot 2023-02-14 10:14:07 +01:00 
Referenced by commit 4ec1c76afc, Fix T48634: Interpolation and distribution of Children Particles breaks.
Referenced by issue #48634, Interpolation and distribution of Children Particles breaks
1 changed files with 19 additions and 15 deletions
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34
source/blender/blenkernel/intern/particle_distribute.c
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@ -915,7 +915,7 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
element_weight = MEM_callocN(sizeof(float)*totelem, "particle_distribution_weights");
particle_element= MEM_callocN(sizeof(int)*totpart, "particle_distribution_indexes");
element_sum = MEM_callocN(sizeof(float)*(totelem+1), "particle_distribution_sum");
element_sum = MEM_mallocN(sizeof(*element_sum) * totelem, "particle_distribution_sum");
jitter_offset = MEM_callocN(sizeof(float)*totelem, "particle_distribution_jitoff");
/* Calculate weights from face areas */
@ -1010,9 +1010,10 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
inv_totweight = (totweight > 0.f ? 1.f/totweight : 0.f);
/* Calculate cumulative weights */
element_sum[0] = 0.0f;
for (i=0; i<totelem; i++)
element_sum[i+1] = element_sum[i] + element_weight[i] * inv_totweight;
element_sum[0] = element_weight[0] * inv_totweight;
for (i = 1; i < totelem; i++) {
element_sum[i] = element_sum[i - 1] + element_weight[i] * inv_totweight;
}
/* Finally assign elements to particles */
if ((part->flag&PART_TRAND) || (part->simplify_flag&PART_SIMPLIFY_ENABLE)) {
@ -1020,7 +1021,7 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
for (p=0; p<totpart; p++) {
/* In theory element_sum[totelem] should be 1.0, but due to float errors this is not necessarily always true, so scale pos accordingly. */
pos= BLI_frand() * element_sum[totelem];
pos= BLI_frand() * element_sum[totelem - 1];
particle_element[p] = distribute_binary_search(element_sum, totelem, pos);
particle_element[p] = MIN2(totelem-1, particle_element[p]);
jitter_offset[particle_element[p]] = pos;
@ -1029,7 +1030,7 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
else {
double step, pos;
step= (totpart < 2) ? 0.5 : 1.0/(double)totpart;
step = (totpart < 2) ? 0.5 : 1.0 / (double)totpart;
/* This is to address tricky issues with vertex-emitting when user tries (and expects) exact 1-1 vert/part
* distribution (see T47983 and its two example files). It allows us to consider pos as
* 'midpoint between v and v+1' (or 'p and p+1', depending whether we have more vertices than particles or not),
@ -1038,22 +1039,25 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
pos = (totpart < totelem) ? 0.5 / (double)totelem : step * 0.5; /* We choose the smaller step. */
}
else {
pos = 1e-6; /* tiny offset to avoid zero weight face */
pos = 0.0;
}
i= 0;
for (p=0; p<totpart; p++, pos+=step) {
while ((i < totelem) && (pos > (double)element_sum[i + 1]))
i++;
/* Avoid initial zero-weight items. */
for (i = 0; (element_sum[i] == 0.0) && (i < totelem - 1); i++);
particle_element[p] = MIN2(totelem-1, i);
for (p = 0; p < totpart; p++, pos += step) {
for ( ; (pos > (double)element_sum[i]) && (i < totelem - 1); i++);
/* avoid zero weight face */
if (p == totpart-1 && element_weight[particle_element[p]] == 0.0f)
particle_element[p] = particle_element[p-1];
particle_element[p] = i;
jitter_offset[particle_element[p]] = pos;
}
/* Avoid final zero weight items. */
BLI_assert(p == totpart);
if (element_weight[particle_element[--p]] == 0.0f) {
particle_element[p] = particle_element[p - 1];
}
}
MEM_freeN(element_sum);