Utils.cpp

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/*
   Copyright 2022 Rishi Challa
 
   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 "Utils.hpp"
 
#include <delaunator.hpp>
 
#include <iterator>
#include <algorithm>
 
using namespace Kale;
 
std::pair<std::vector<Vector2f>, std::vector<unsigned int>> Kale::triangulatePath(const Vector2f* begin, const Vector2f* end) {
    std::vector<double> coords;
    coords.reserve(std::distance(begin, end) * 2);
    
    std::for_each(begin, end, [&](const Vector2f& vec) {
        coords.push_back(static_cast<double>(vec.x));
        coords.push_back(static_cast<double>(vec.y));
    });
 
    delaunator::Delaunator d(coords);
 
    std::pair<std::vector<Vector2f>, std::vector<unsigned int>> output;
    std::vector<Vector2f>& vertices = output.first;
    std::vector<unsigned int>& elements = output.second;
 
    elements.reserve(d.triangles.size());
    std::transform(d.triangles.begin(), d.triangles.end(), std::back_inserter(elements), [](size_t index) {
        return static_cast<unsigned int>(index);
    });
 
    vertices.reserve(d.coords.size() / 2);
    for (size_t i = 0; i < d.coords.size(); i += 2)
        vertices.emplace_back(static_cast<float>(d.coords[i]), static_cast<float>(d.coords[i+1]));
 
    return output;
}
 
std::pair<std::vector<float>, std::vector<unsigned int>> Kale::triangulatePathFloat(const Vector2f* begin, const Vector2f* end) {
    std::vector<double> coords;
    coords.reserve(std::distance(begin, end) * 2);
    
    for (const Vector2f* it = begin; it != end; ++it) {
        const Vector2f& vec = *it;
        coords.push_back(static_cast<double>(vec.x));
        coords.push_back(static_cast<double>(vec.y));
    }
 
    delaunator::Delaunator d(coords);
 
    std::pair<std::vector<float>, std::vector<unsigned int>> output;
    std::vector<float>& vertices = output.first;
    std::vector<unsigned int>& elements = output.second;
 
    elements.reserve(d.triangles.size());
    std::transform(d.triangles.begin(), d.triangles.end(), std::back_inserter(elements), [](size_t index) {
        return static_cast<unsigned int>(index);
    });
 
    vertices.reserve(d.coords.size());
    std::transform(d.coords.begin(), d.coords.end(), std::back_inserter(vertices), [](double value) {
        return static_cast<float>(value);
    });
 
    return output;
}