private void UpdateColor()
{
Color newColor = targetImage.color;
newColor.a = panel.Alpha() * maxRate;
targetImage.color = newColor;
}
/// <summary>
/// パネルのAlphaを設定
/// </summary>
private void UpdatePanelAlpha()
{
float current = panel.Alpha();
current += FadeValue();
current = Mathf.Max(0, Mathf.Min(current, panel.MaxAlpha()));
panel.SetAlpha(current);
}