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Diffstat (limited to 'intern/cycles/util/math_cdf.h')
-rw-r--r-- | intern/cycles/util/math_cdf.h | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/intern/cycles/util/math_cdf.h b/intern/cycles/util/math_cdf.h new file mode 100644 index 00000000000..4c57dac4bbe --- /dev/null +++ b/intern/cycles/util/math_cdf.h @@ -0,0 +1,75 @@ +/* + * Copyright 2011-2015 Blender Foundation + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#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. */ + for (int i = 0; i <= resolution; i++) { + cdf[i] /= cdf[resolution]; + } +} + +/* 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__ */ |