var ourAlpha : float;

function Start() {
ourAlpha = 0.0;
}

function Update() {
var per2sec = 0.7f / 2.0f;
ourAlpha = ourAlpha + per2sec * Time.deltaTime;
if(ourAlpha>0.7f) {
ourAlpha = 0.7f; // maximam check
}
renderer.material.color.a = ourAlpha;
}