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/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "camera.h"
#include "device.h"
#include "filter.h"
#include "scene.h"
#include "util_algorithm.h"
#include "util_debug.h"
#include "util_math.h"
CCL_NAMESPACE_BEGIN
Filter::Filter()
{
filter_type = FILTER_BOX;
filter_width = 1.0f;
need_update = true;
}
Filter::~Filter()
{
}
static float filter_func_box(float v, float width)
{
return (float)1;
}
static float filter_func_gaussian(float v, float width)
{
v *= (float)2/width;
return (float)expf((float)-2*v*v);
}
static vector<float> filter_table(FilterType type, float width)
{
const int filter_table_size = 256;
vector<float> filter_table_cdf(filter_table_size+1);
vector<float> filter_table(filter_table_size+1);
float (*filter_func)(float, float) = NULL;
int i, half_size = filter_table_size/2;
switch(type) {
case FILTER_BOX:
filter_func = filter_func_box;
break;
case FILTER_GAUSSIAN:
filter_func = filter_func_gaussian;
break;
default:
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);
}
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;
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);
}
return filter_table;
}
void Filter::device_update(Device *device, DeviceScene *dscene)
{
if(!need_update)
return;
device_free(device, dscene);
/* update __filter_table */
vector<float> table = filter_table(filter_type, filter_width);
dscene->filter_table.copy(&table[0], table.size());
device->tex_alloc("__filter_table", dscene->filter_table, true);
need_update = false;
}
void Filter::device_free(Device *device, DeviceScene *dscene)
{
device->tex_free(dscene->filter_table);
dscene->filter_table.clear();
}
CCL_NAMESPACE_END
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