line-of-hearing.js

function withinRadius(v, r) {
  return v.l < r;
}

function getDistance(playerA, playerB) {
  const x = playerA.position.x - playerB.position.x;
  const y = playerA.position.y - playerB.position.y;
  const l = Math.sqrt((x * x) + (y * y));
  return {x, y, l};
}

function makeUnit(v) {
  return {x: v.x / v.l, y: v.y / v.l, l: 1};
}

function angleFromAtan(a) {
  if (a > 0) {
    return (x * 360 / (2 * Math.PI));
  } else {
    return ((2*PI + x) * 360 / (2*PI));
  }
}

function movementBearing(playerA, playerB) {
  // Get the distance as a unit vector
  const v = getDistance(playerA, playerB);
  if (withinRadius(v, playerB.hearing.radius)) {
    const uv = makeUnit(v);
    return angleFromAtan(Math.atan2(uv.y, uv.x));
  } else {
    return -1;
  }
}