vectozavr-shooter/engine/Triangle.cpp

//
// Created by Иван Ильин on 13.01.2021.
//

#include "Triangle.h"
#include "Consts.h"

Triangle::Triangle(const Vec4D &p1, const Vec4D &p2, const Vec4D &p3, sf::Color color) : _color(color),
                                                                                         _points{p1, p2, p3} {
    calculateNormal();
}

void Triangle::calculateNormal() {
    Vec3D v1 = Vec3D(_points[1] - _points[0]);
    Vec3D v2 = Vec3D(_points[2] - _points[0]);
    Vec3D crossProduct = v1.cross(v2);

    if (crossProduct.sqrAbs() > Consts::EPS) {
        _normal = crossProduct.normalized();
    } else {
        _normal = Vec3D(0);
    }
}

Triangle::Triangle(const Triangle &triangle) : _points{triangle._points[0], triangle._points[1], triangle._points[2]},
                                               _color(triangle._color), _normal(triangle._normal) {
}

Triangle Triangle::operator*(const Matrix4x4 &matrix4X4) const {
    return Triangle(matrix4X4 * _points[0], matrix4X4 * _points[1], matrix4X4 * _points[2], _color);
}

Vec3D Triangle::norm() const {
    return _normal;
}

const Vec4D& Triangle::operator[](int i) const {
    return _points[i];
}

bool Triangle::isPointInside(const Vec3D &point) const {
    Vec3D triangleNorm = norm();

    double dot1 = (point - Vec3D(_points[0])).cross(Vec3D(_points[1] - _points[0])).dot(triangleNorm);
    double dot2 = (point - Vec3D(_points[1])).cross(Vec3D(_points[2] - _points[1])).dot(triangleNorm);
    double dot3 = (point - Vec3D(_points[2])).cross(Vec3D(_points[0] - _points[2])).dot(triangleNorm);

    if ((dot1 >= 0 && dot2 >= 0 && dot3 >= 0) || (dot1 <= 0 && dot2 <= 0 && dot3 <= 0)) {
        return true;
    }
    return false;
}