73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
//
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// Created by Иван Ильин on 19.01.2021.
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//
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#include "Plane.h"
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Plane::Plane(const Triangle &tri) : _normal(tri.norm()), _point(tri[0]) {
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}
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Plane::Plane(const Vec3D &N, const Vec3D &P) : _normal(N.normalized()), _point(P) {
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}
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double Plane::distance(const Vec3D &point) const {
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return point.dot(_normal) - _point.dot(_normal);
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}
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std::pair<Vec3D, double> Plane::intersection(const Vec3D &start, const Vec3D &end) const {
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double s_dot_n = start.dot(_normal);
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double k = (s_dot_n - _point.dot(_normal)) / (s_dot_n - end.dot(_normal));
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Vec3D res = start + (end - start) * k;
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return std::make_pair(res, k);
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}
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std::vector<Triangle> Plane::clip(const Triangle &tri) const {
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std::vector<Triangle> result;
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std::vector<Vec3D> insidePoints;
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std::vector<Vec3D> outsidePoints;
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double distances[3] = {distance(Vec3D(tri[0])),
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distance(Vec3D(tri[1])),
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distance(Vec3D(tri[2]))};
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for (int i = 0; i < 3; i++) {
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if (distances[i] >= 0) {
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insidePoints.emplace_back(tri[i]);
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} else {
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outsidePoints.emplace_back(tri[i]);
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}
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}
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if (insidePoints.size() == 1) {
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std::pair<Vec3D, double> intersect1 = intersection(insidePoints[0], outsidePoints[0]);
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std::pair<Vec3D, double> intersect2 = intersection(insidePoints[0], outsidePoints[1]);
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result.emplace_back(insidePoints[0].makePoint4D(),
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intersect1.first.makePoint4D(),
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intersect2.first.makePoint4D(),
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tri.color());
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}
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if (insidePoints.size() == 2) {
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std::pair<Vec3D, double> intersect1 = intersection(insidePoints[0], outsidePoints[0]);
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std::pair<Vec3D, double> intersect2 = intersection(insidePoints[1], outsidePoints[0]);
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result.emplace_back(insidePoints[0].makePoint4D(),
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intersect1.first.makePoint4D(),
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insidePoints[1].makePoint4D(),
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tri.color());
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result.emplace_back(intersect1.first.makePoint4D(),
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intersect2.first.makePoint4D(),
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insidePoints[1].makePoint4D(),
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tri.color());
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}
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if (insidePoints.size() == 3) {
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result.emplace_back(tri);
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}
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return result;
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}
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