flying-balls/polygon_generator.cc

#include "polygon_generator.h"

#include <cassert>
#include <cmath>

static double to_rad(double angle_in_deg) {
    static double PI_180 = M_PI / 180;
    return angle_in_deg * PI_180;
}

polygon poly_generate::rectangle(double width, double height) {
    assert(width > 0);
    assert(height > 0);
    return polygon{{0, 0},
        0,
        {{-width / 2, -height / 2},
            {width / 2, -height / 2},
            {width / 2, height / 2},
            {-width / 2, height / 2}}};
}

polygon poly_generate::triangle(double side1, double side2, double angle) {
    assert(side1 > 0);
    assert(side2 > 0);
    vec2d points[] = {{0, 0},
        {side1, 0},
        {side2 * std::cos(to_rad(angle)), side2 * std::sin(to_rad(angle))}};

    vec2d barycenter = {
        (points[0].x + points[1].x + points[2].x) / 3,
        (points[0].y + points[1].y + points[2].y) / 3,
    };

    for (unsigned int i = 0; i < 3; ++i)
        points[i] -= barycenter;
    return polygon{{0, 0}, 0, {std::begin(points), std::end(points)}};
}