function getAngleRadians(x0, y0, x1, y1) {
    // radians = atan2(deltaY, deltaX)
    const y = y1 - y0;
    const x = x1 - x0;
    return Math.atan2(y, x);
}

function getAngleDeg(x0, y0, x1, y1) {
    // degrees = atan2(deltaY, deltaX) * (180 / PI)
    const y = y1 - y0;
    const x = x1 - x0;
    return Math.atan2(y, x) * (180 / Math.PI);
}