72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
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/*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* Copyright 2018 Danny Robson <danny@nerdcruft.net>
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*/
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#include "sample.hpp"
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#include "../point.hpp"
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#include <random>
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///////////////////////////////////////////////////////////////////////////////
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std::vector<util::point2f>
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util::geom::poisson_sample (util::extent2i area, float distance, int samples)
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{
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std::vector<util::point2f> selected;
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std::vector<util::point2f> candidates (samples);
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std::uniform_real_distribution<float> dist_w (0, area.w);
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std::uniform_real_distribution<float> dist_h (0, area.h);
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std::random_device rd;
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std::default_random_engine gen;
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selected.push_back ({
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dist_w (gen),
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dist_h (gen),
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});
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auto min_distance = [&selected] (auto q) {
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float min_d = INFINITY;
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for (auto s: selected)
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if (auto s_d = util::distance2 (s, q); s_d < min_d)
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min_d = s_d;
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return min_d;
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};
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while (1) {
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util::point2f p;
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float d = -INFINITY;
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for (int i = 0; i < samples; ++i) {
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util::point2f candidate { dist_w (gen), dist_h (gen) };
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if (auto p_d = min_distance (candidate); p_d > d) {
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p = candidate;
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d = p_d;
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}
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}
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if (std::sqrt (d) < distance)
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break;
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selected.push_back (p);
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}
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return selected;
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}
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