Momentum-Apps/vec2.h

#pragma once
#include <stdbool.h>
#include <cmath>

#define VEC2_EPSILON (float)0.001

class Vec2 {
public:
    float x;
    float y;

    Vec2()
        : x(0)
        , y(0) {
    }
    Vec2(float x_, float y_)
        : x(x_)
        , y(y_) {
    }

    Vec2 operator+(const Vec2& rhs) const {
        return Vec2(x + rhs.x, y + rhs.y);
    }
    Vec2 operator+(float s) const {
        return Vec2(x + s, y + s);
    }
    void operator+=(const Vec2& rhs) {
        x += rhs.x;
        y += rhs.y;
    }
    Vec2 operator-(const Vec2& rhs) const {
        return Vec2(x - rhs.x, y - rhs.y);
    }
    Vec2 operator-(float s) const {
        return Vec2(x - s, y - s);
    }
    void operator-=(const Vec2& rhs) {
        x -= rhs.x;
        y -= rhs.y;
    }
    Vec2 operator*(float s) const {
        return Vec2(x * s, y * s);
    }
    void operator*=(float s) {
        x *= s;
        y *= s;
    }

    Vec2 operator/(float s) const {
        return Vec2(x / s, y / s);
    }

    bool operator==(const Vec2& rhs) const {
        return x == rhs.x && y == rhs.y;
    }

    // Magnitude / length of vector
    float mag() const {
        return sqrtf(x * x + y * y);
    }
    // Magnitude squared
    float mag2() const {
        return x * x + y * y;
    }

    // Dot product: this.x * v.x + this.y * v.y
    float dot(const Vec2& v) const {
        return x * v.x + y * v.y;
    }

    // Cross product
    float cross(const Vec2& v) const {
        return x * v.y - y * v.x;
    }

    void normalize(void) {
        float len = mag();
        if(len > VEC2_EPSILON) {
            float inverse_len = 1.0f / len;
            x *= inverse_len;
            y *= inverse_len;
        }
    }

    // Distance squared between this and next
    float dist2(const Vec2& v) const {
        float dx = x - v.x;
        float dy = y - v.y;
        return dx * dx + dy * dy;
    }
    // Distance between tihs and next
    float dist(const Vec2& v) const {
        return sqrtf(dist2(v));
    }

    // void rotate(float radians) {
    //     float c = std::cos(radians);
    //     float s = std::sin(radians);
    //     float xp = x * c - y * s;
    //     float yp = x * s + y * c;
    //     x = xp;
    //     y = yp;
    // }
};

inline Vec2 operator*(float s, const Vec2& v) {
    return Vec2(s * v.x, s * v.y);
}

// Vec2 Vec2_unit(const Vec2& v);

// // Returns true if point b lies between points a and c
// bool Vec2_colinear(const Vec2& a, const Vec2& b, const Vec2& c);

// // Returns the closest point to the line segment ab and p
Vec2 Vec2_closest(const Vec2& a, const Vec2& b, const Vec2& p);

// // Returns the closest point to the infinite ray ab and p
// Vec2 Vec2_closest_ray(const Vec2& a, const Vec2& b, const Vec2& p);

// // Returns if A, B, C are listed in counterclockwise order
// bool Vec2_ccw(const Vec2& A, const Vec2& B, const Vec2& C);

// // Returns if line AB intersects with line CD
// bool Vec2_intersect(const Vec2& A, const Vec2& B, const Vec2& C, const Vec2& D);

// // Returns intersection point of two lines AB and CD.
// // The intersection point may not lie on either segment.
// Vec2 Vec2_intersection(const Vec2& A, const Vec2& B, const Vec2& C, const Vec2& D);

// // Returns distance of ray origin to intersection point on line segment. -1 if no intersection
// float Vec2_ray_line_segment_intersect(
//     const Vec2& origin,
//     const Vec2& dir,
//     const Vec2& l1,
//     const Vec2& l2);

// bool Vec2_project(const Vec2& A, const Vec2& B, const Vec2& P, Vec2& dst);

// bool Vec2_point_circle_collide(const Vec2& point, const Vec2& circle, float radius);

// bool Vec2_line_circle_collide(
//     const Vec2 a,
//     const Vec2 b,
//     const Vec2 circle,
//     float radius,
//     Vec2* nearest);