Render TOP fading alpha

In a current network I need to be able to trigger the fade up and down of the alpha for a Render TOP.
Read documentation but nothing is obvious.
What would be the best way to do this, via GLSl or using a separate connected TOP or?

hi,
you can use a level TOP to access the opacity parameter.
You can then use a button to trigger the opacity through a filterCHOP to ease in/out the value.

Thanks will try that.

You can also have a look at tweener for a more programmatic approach by scripting the fades directly: