Hello.

I just need to make a previs flipbook from the viewport showing an animated blend between two texture maps.
I know that I can make just a single texture map to show in the viewport with openGL tags so I thought that I could make it through COPs and "op:" expression and in theory it works but the viewport doesn't refresh the blend as it should.

Any way to do this very simple thing (al least in other apps it is) properly?

If you want the viewer to pick up the animation, you'll need to put $F in square brackets on the end of the op: expression. Like

Thanks!

It's working nicely.
In the diffuse channel no problem, it works ok but if I plug it in the opacity chanel still doesn't refresh. Any idea why?

And just for curiosity, where is this documented? I've searched in the help docs but I haven't found anything about it.