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Cycles: Optimize Equi-Angular sampling using binary range search. 

Patch by Lukas Tönne and myself.
This commit is contained in:
Thomas Dinges 2014-08-14 20:21:36 +02:00
parent 5af00a3d12
commit 32a5313b41
1 changed files with 24 additions and 6 deletions
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30
intern/cycles/kernel/kernel_volume.h
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@ -853,15 +853,33 @@ ccl_device VolumeIntegrateResult kernel_volume_decoupled_scatter(
float3 step_pdf_distance = make_float3(1.0f, 1.0f, 1.0f);
if(segment->numsteps > 1) {
/* todo: optimize using binary search */
float3 prev_cdf_distance = make_float3(0.0f, 0.0f, 0.0f);
for(int i = 0; i < segment->numsteps-1; i++, step++) {
if(sample_t < step->t)
break;
int numsteps = segment->numsteps;
int high = numsteps - 1;
int low = 0;
int mid;
prev_t = step->t;
prev_cdf_distance = step->cdf_distance;
while(low < high) {
mid = (low + high) >> 1;
if(sample_t < step[mid].t)
high = mid;
else if(sample_t >= step[mid + 1].t)
low = mid + 1;
else {
/* found our interval in step[mid] .. step[mid+1] */
prev_t = step[mid].t;
prev_cdf_distance = step[mid].cdf_distance;
step += mid+1;
break;
}
}
if(low >= numsteps - 1) {
prev_t = step[numsteps - 1].t;
prev_cdf_distance = step[numsteps-1].cdf_distance;
step += numsteps - 1;
}
/* pdf for picking step with distance sampling */