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Fix for [#25506] Hair showing up in places not assigned by a weightmap

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* Two separate bugs, with very similar symptoms.
* The distribution binary search didn't work correctly in cases where there were a lot of faces with 0 weights.
* Maximum distribution sum should have been exactly 1, but due to the wonderful nature of floats this wasn't the case at all.
This commit is contained in:
Janne Karhu
2011-01-07 10:13:30 +00:00
parent 57a3cff3b8
commit 96128ee69f
1 changed files with 10 additions and 3 deletions
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13
source/blender/blenkernel/intern/particle_system.c
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@@ -616,15 +616,21 @@ static void psys_uv_to_w(float u, float v, int quad, float *w)
}
}
/* Find the index in "sum" array before "value" is crossed. */
static int binary_search_distribution(float *sum, int n, float value)
{
int mid, low=0, high=n;
if(value == 0.f)
return 0;
while(low <= high) {
mid= (low + high)/2;
if(sum[mid] <= value && value <= sum[mid+1])
if(sum[mid] < value && value <= sum[mid+1])
return mid;
else if(sum[mid] > value)
if(sum[mid] >= value)
high= mid - 1;
else if(sum[mid] < value)
low= mid + 1;
@@ -1297,7 +1303,8 @@ static int psys_threads_init_distribution(ParticleThread *threads, Scene *scene,
float pos;
for(p=0; p<totpart; p++) {
pos= BLI_frand();
/* In theory sys[tot] should be 1.0, but due to float errors this is not necessarily always true, so scale pos accordingly. */
pos= BLI_frand() * sum[tot];
index[p]= binary_search_distribution(sum, tot, pos);
index[p]= MIN2(tot-1, index[p]);
jitoff[index[p]]= pos;