diff options
Diffstat (limited to 'intern/cycles/util/util_math_cdf.cpp')
-rw-r--r-- | intern/cycles/util/util_math_cdf.cpp | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/intern/cycles/util/util_math_cdf.cpp b/intern/cycles/util/util_math_cdf.cpp new file mode 100644 index 00000000000..cafe4c5abeb --- /dev/null +++ b/intern/cycles/util/util_math_cdf.cpp @@ -0,0 +1,67 @@ +/* + * 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. + */ + +#include "util_math_cdf.h" + +#include "util_algorithm.h" +#include "util_math.h" + +CCL_NAMESPACE_BEGIN + +/* 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) { + const float inv_resolution = 1.0f / (float)resolution; + const float range = to - from; + inv_cdf.resize(resolution); + if(make_symmetric) { + const int half_size = (resolution - 1) / 2; + for(int i = 0; i <= half_size; i++) { + float x = i / (float)half_size; + int index = upper_bound(cdf.begin(), cdf.end(), x) - cdf.begin(); + float t; + if(index < cdf.size()) { + t = (x - cdf[index])/(cdf[index+1] - cdf[index]); + } else { + t = 0.0f; + index = cdf.size() - 1; + } + float y = ((index + t) / (resolution - 1)) * (2.0f * range); + inv_cdf[half_size+i] = 0.5f*(1.0f + y); + inv_cdf[half_size-i] = 0.5f*(1.0f - y); + } + } + else { + for(int i = 0; i <= resolution; i++) { + float x = from + range * (float)i * inv_resolution; + int index = upper_bound(cdf.begin(), cdf.end(), x) - cdf.begin(); + float t; + if(index < cdf.size()) { + t = (x - cdf[index])/(cdf[index+1] - cdf[index]); + } else { + t = 0.0f; + index = resolution; + } + inv_cdf[i] = (index + t) * inv_resolution; + } + } +} + +CCL_NAMESPACE_END |