/**
 * Keys to a direction on the map.
 *
 * The server has always been told a world-space direction, and that contract
 * does not change: from inside the player's head W means "the way I am
 * looking", so the keys are turned by the view angle before they are sent.
 * In the top-down view the keys are the compass they always were.
 */

/**
 * `ax` is right on the keyboard (+1 for D), `ay` is down the screen (+1 for
 * S, so forward is -1). `out` is filled and returned: no allocation.
 */
export function moveVector(ax, ay, yaw, out = { x: 0, y: 0 }) {
  const cos = Math.cos(yaw);
  const sin = Math.sin(yaw);
  out.x = cos * -ay - sin * ax;
  out.y = sin * -ay + cos * ax;
  return out;
}