CODE EXAMPLE FOR C

unity change transparency script

public GameObject gameObject;

//gameObject.GetComponent<Renderer>().material.color = new Color(r, g, b, a);
//gameObject.GetComponent<Renderer>().material.color = new Color(255.0f, 255.0f, 255.0f, 0.0f);
gameObject.GetComponent<Renderer>().material.color = new Color(255.0f, 255.0f, 255.0f, 100.0f);