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Cycles: Use new CDF evaluation utility for the pixel filter

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Filter table should stay exactly the same, no changes in the render
results are expected at all.
This commit is contained in:
Sergey Sharybin 2015-10-26 20:23:18 +05:00
parent 548ef2d88b
commit c07c066685
1 changed files with 17 additions and 33 deletions
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50
intern/cycles/render/film.cpp
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@ -26,6 +26,7 @@
#include "util_debug.h"
#include "util_foreach.h"
#include "util_math.h"
#include "util_math_cdf.h"
CCL_NAMESPACE_BEGIN
@ -214,11 +215,8 @@ static float filter_func_gaussian(float v, float width)
static vector<float> filter_table(FilterType type, float width)
{
const int filter_table_size = FILTER_TABLE_SIZE-1;
vector<float> filter_table_cdf(filter_table_size+1);
vector<float> filter_table(filter_table_size+1);
vector<float> filter_table(FILTER_TABLE_SIZE);
float (*filter_func)(float, float) = NULL;
int i, half_size = filter_table_size/2;
switch(type) {
case FILTER_BOX:
@ -231,37 +229,23 @@ static vector<float> filter_table(FilterType type, float width)
assert(0);
}
/* compute cumulative distribution function */
filter_table_cdf[0] = 0.0f;
for(i = 0; i < filter_table_size; i++) {
float x = i*width*0.5f/(filter_table_size-1);
float y = filter_func(x, width);
filter_table_cdf[i+1] += filter_table_cdf[i] + fabsf(y);
}
/* Create importance sampling table. */
for(i = 0; i <= filter_table_size; i++)
filter_table_cdf[i] /= filter_table_cdf[filter_table_size];
/* create importance sampling table */
for(i = 0; i <= half_size; i++) {
float x = i/(float)half_size;
int index = upper_bound(filter_table_cdf.begin(), filter_table_cdf.end(), x) - filter_table_cdf.begin();
float t;
/* TODO(sergey): With the even filter table size resolution we can not
* really make it nice symmetric importance map without sampling full range
* (meaning, we would need to sample full filter range and not use the
* make_symmetric argument).
*
* Current code matches exactly initial filter table code, but we should
* consider either making FILTER_TABLE_SIZE odd value or sample full filter.
*/
if(index < filter_table_size+1) {
t = (x - filter_table_cdf[index])/(filter_table_cdf[index+1] - filter_table_cdf[index]);
}
else {
t = 0.0f;
index = filter_table_size;
}
float y = ((index + t)/(filter_table_size))*width;
filter_table[half_size+i] = 0.5f*(1.0f + y);
filter_table[half_size-i] = 0.5f*(1.0f - y);
}
util_cdf_inverted(FILTER_TABLE_SIZE,
0.0f,
width * 0.5f,
function_bind(filter_func, _1, width),
true,
filter_table);
return filter_table;
}