Function getAngleFromPoint

src/helpers/helpers.math.ts:124–142

(
  centrePoint: Point,
  anglePoint: Point
)

// Gets the angle from vertical upright to the point about a centre.
export function getAngleFromPoint(
  centrePoint: Point,
  anglePoint: Point
) {
  const distanceFromXCenter = anglePoint.x - centrePoint.x;
  const distanceFromYCenter = anglePoint.y - centrePoint.y;
  const radialDistanceFromCenter = Math.sqrt(distanceFromXCenter * distanceFromXCenter + distanceFromYCenter * distanceFromYCenter);

  let angle = Math.atan2(distanceFromYCenter, distanceFromXCenter);

  if (angle < (-0.5 * PI)) {
    angle += TAU; // make sure the returned angle is in the range of (-PI/2, 3PI/2]
  }

  return {
    angle,
    distance: radialDistanceFromCenter
  };
}

export function distanceBetweenPoints(pt1: Point, pt2: Point) {
  return Math.sqrt(Math.pow(pt2.x - pt1.x, 2) + Math.pow(pt2.y - pt1.y, 2));