Point calculation helper functions

point-helper.js

// =============================================================================
// POINT CALCULATION HELPER FUNCTIONS
// 
// This is a collection of various mathematical helper functions, for manipula-
// ting points and measuring angles and distances.
// 
// Inside a function, no other function form the list is used, to ensure you can
// use the indipendently.
// =============================================================================

/**
 * Get the distance between two points
 * 
 * @param  {Object} p1 Point A – {x: Int, y: Int}
 * @param  {Object} p2 Point B – {x: Int, y: Int}
 * @return {Number}    The distance between `p1` and `p2`.
 */
const distance = (p1, p2) => {
  const dx = p1.x - p2.x,
        dy = p1.y - p2.y;
  return Math.sqrt(dx * dx + dy * dy);
};

/**
 * The angle between two points in radians.
 * 
 * @param  {Object} p1 Point A – {x: Int, y: Int}
 * @param  {Object} p2 Point B – {x: Int, y: Int}
 * @return {Number}    The angle between `p1` and `p2` in radians.
 */
const angleInRadians = (p1, p2) => Math.atan2(p2.y - p1.y, p2.x - p1.x);

/**
 * The angle between two points in radians.
 * 
 * @param  {Object} p1 Point A – {x: Int, y: Int}
 * @param  {Object} p2 Point B – {x: Int, y: Int}
 * @return {Number}    The angle between `p1` and `p2` in radians.
 */
const angleInDegrees = (p1, p2) => Math.atan2(p2.y - p1.y, p2.x - p1.x) * 180 / Math.PI;

/**
 * Convert degrees to radians.
 * 
 * @param  {Number} degrees An angle in degrees
 * @return {Number}         The angle in radians
 */
const degreesToRadians = degrees => degrees * Math.PI / 180;

/**
 * Convert radians to degreess.
 * 
 * @param  {Number} radians An angle in radians
 * @return {Number}         The angle in degrees
 */
const radiansToDegrees = radians => radians * 180 / Math.PI;

/**
 * Move `point` by `distance` in a direction defined by `angle`.
 * 
 * @param  {Object} point    The point, that shall be moved.
 * @param  {Number} distance The distance, the point will be moved.
 * @param  {Number} angle    The direction __in radians__, the point will be 
 *                           moved in.
 */
const movePoint = (point, distance, angle) => {
  point.x += distance * Math.cos(angle);
  point.y += distance * Math.sin(angle);
};