IEnumerator setAlpha() { //music transition day->night BGM_manager.musicTransition(); for (float i = 0; i <= 2.5f; i += Time.deltaTime) { image.color = new Color(0.0f, 0.0f, 0.0f, i * 0.4f); yield return(0); } parameters.gotoNextDay(); UI.GetComponent <UIDisplay>().displayed = false; for (float i = 0; i <= 2.5f; i += Time.deltaTime) { image.color = new Color(0.0f, 0.0f, 0.0f, (1.0f - i * 0.4f)); yield return(0); } //music transition night->day BGM_manager.musicTransition(); image.color = new Color(0.0f, 0.0f, 0.0f, 0.0f); }