public void Update()
{
float timedSpeed = speed * Time.deltaTime;
Color c = material.color;
if (c.a != opacity) {
float diff = c.a - opacity;
if (Mathf.Abs(diff) > timedSpeed) {
if (diff < 0)
c.a += timedSpeed;
else
c.a -= timedSpeed;
} else {
c.a = this.opacity;
}
material.color = c;
}
}