normalizeMousePosition()

function normalizeMousePosition(ev) {
    var normalizedX, normalizedY;

    // Desktop
    if (ev.clientX != undefined) {
        normalizedX = -2 * (.5 - ev.clientX / window.innerWidth);
        normalizedY = 2 * (.5 - ev.clientY / window.innerHeight);
    }
    // Mobile 
    else {
        normalizedX = -2 * (.5 - ev.touches[0].clientX / window.innerWidth);
        normalizedY = 2 * (.5 - ev.touches[0].clientY / window.innerHeight);
    }    
    
    return {
        x: normalizedX,
        y: normalizedY
    }
}