Vector2.ts

export class Vector2 {
  protected _x: number
  protected _y: number


  constructor(x: number, y: number) {
    this._x = x || 0
    this._y = y || 0
  }

  get x(): number {
    return this._x
  }
  set x(x: number) {
    this._x = x
  }

  get y(): number {
    return this._y
  }
  set y(y: number) {
    this._y = y
  }

  add(vector: Vector2) {
    return new Vector2(this.x + vector.x, this.y + vector.y);
  }

  subtract(vector: Vector2) {
    return new Vector2(this.x - vector.x, this.y - vector.y);
  }

  multiply(vector: Vector2) {
    return new Vector2(this.x * vector.x, this.y * vector.y);
  }

  scale(scalar: number) {
    return new Vector2(this.x * scalar, this.y * scalar);
  }

  dot(vector: Vector2) {
    return (this.x * vector.x + this.y + vector.y);
  }

  moveTowards(vector: Vector2, time: number) {
    // Linearly interpolates between vectors A and B by t.
    // t = 0 returns A, t = 1 returns B
    time = Math.min(time, 1); // still allow negative t
    const diff = vector.subtract(this);
    return this.add(diff.scale(time));
  }

  magnitude() {
    return Math.sqrt(this.magnitudeSqr());
  }

  magnitudeSqr() {
    return (this.x * this.x + this.y * this.y);
  }

  distance(vector: Vector2) {
    return Math.sqrt(this.distanceSqr(vector));
  }

  distanceSqr(vector: Vector2) {
    const deltaX = this.x - vector.x;
    const deltaY = this.y - vector.y;
    return (deltaX * deltaX + deltaY * deltaY);
  }

  normalize() {
    const mag = this.magnitude();
    const vector = this.clone();
    if(Math.abs(mag) < 1e-9) {
      vector.x = 0;
      vector.y = 0;
    } else {
      vector.x /= mag;
      vector.y /= mag;
    }
    return vector;
  }

  clone() {
    return new Vector2(this.x, this.y)
  }

  angle() {
    return Math.atan2(this.y, this.x);
  }

  rotate(alpha: number) {
    const cos = Math.cos(alpha);
    const sin = Math.sin(alpha);
    const vector = new Vector2(0, 0);
    vector.x = this.x * cos - this.y * sin;
    vector.y = this.x * sin + this.y * cos;
    return vector;
  }

  toPrecision(precision: number) {
    const vector = this.clone();
    vector.x = Number(vector.x.toFixed(precision));
    vector.y = Number(vector.y.toFixed(precision));
    return vector;
  }

  toString() {
    const vector = this.toPrecision(1);
    return ('[' + vector.x + '; ' + vector.y + ']');
  }

  toSvgString() {
    const vector = this.toPrecision(1);
    return (vector.x + ',' + vector.y);
  }
}