66 lines
2.0 KiB
C++
66 lines
2.0 KiB
C++
/* SPDX-FileCopyrightText: 2011-2022 Blender Foundation
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0 */
|
|
|
|
#ifndef __UTIL_MATH_CDF_H__
|
|
#define __UTIL_MATH_CDF_H__
|
|
|
|
#include "util/algorithm.h"
|
|
#include "util/math.h"
|
|
#include "util/vector.h"
|
|
|
|
CCL_NAMESPACE_BEGIN
|
|
|
|
/* Evaluate CDF of a given functor with given range and resolution. */
|
|
template<typename Functor>
|
|
void util_cdf_evaluate(
|
|
const int resolution, const float from, const float to, Functor functor, vector<float> &cdf)
|
|
{
|
|
const int cdf_count = resolution + 1;
|
|
const float range = to - from;
|
|
cdf.resize(cdf_count);
|
|
cdf[0] = 0.0f;
|
|
/* Actual CDF evaluation. */
|
|
for (int i = 0; i < resolution; ++i) {
|
|
float x = from + range * (float)i / (resolution - 1);
|
|
float y = functor(x);
|
|
cdf[i + 1] = cdf[i] + fabsf(y);
|
|
}
|
|
/* Normalize the CDF. */
|
|
float fac = (cdf[resolution] == 0.0f) ? 0.0f : 1.0f / cdf[resolution];
|
|
for (int i = 0; i <= resolution; i++) {
|
|
cdf[i] *= fac;
|
|
}
|
|
cdf[resolution] = 1.0f;
|
|
}
|
|
|
|
/* Invert pre-calculated CDF function. */
|
|
void util_cdf_invert(const int resolution,
|
|
const float from,
|
|
const float to,
|
|
const vector<float> &cdf,
|
|
const bool make_symmetric,
|
|
vector<float> &inv_cdf);
|
|
|
|
/* Evaluate inverted CDF of a given functor with given range and resolution. */
|
|
template<typename Functor>
|
|
void util_cdf_inverted(const int resolution,
|
|
const float from,
|
|
const float to,
|
|
Functor functor,
|
|
const bool make_symmetric,
|
|
vector<float> &inv_cdf)
|
|
{
|
|
vector<float> cdf;
|
|
/* There is no much smartness going around lower resolution for the CDF table,
|
|
* this just to match the old code from pixel filter so it all stays exactly
|
|
* the same and no regression tests are failed.
|
|
*/
|
|
util_cdf_evaluate(resolution - 1, from, to, functor, cdf);
|
|
util_cdf_invert(resolution, from, to, cdf, make_symmetric, inv_cdf);
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|
|
|
|
#endif /* __UTIL_MATH_H_CDF__ */
|