I would duplicate your surface/deform, and mimic link them. Then with a separate axis
put the back side surface offset in Z just a little, making sure your surface priorities are right or turning on z-buffer.
thanks Greg - i tried that (but forgot all about mimic links) and it was getting all confused…probably me.
Anyway, i figured the easier way was to have the clean plate and front plate combined in a comp node and use a gmask to animate between the two whilst watching the result of the curling page…works a treat, just takes a while with multiple pages!
I think I did something like this where I used two surfaces and lit the front only of one and the back only of the other and did an additive transfer mode. I know those details are scant, but I think it may have involved using an action node for each surface, linked their motion with expressions, and used a third to combine them. There was no distort node in the mix. Still eating breakfast, so I can’t check it out.
You can also… create 2 colour sources. Green and Red… Animate the red one in action… add a projector and project green over it but enable ‘front face only’ in the projector… then output UV and motionvectors from action. That’ll give you and ‘ID’ for the front and back. Use the UV32 matchbox (set the action output to 32 bit) to warp your front and back and use the ID to separate…
Actually (slow day) I tested it and it works, with some caveats, such as my lighting being limited to something that won’t spill onto the back. But it also reminded me that I did it a different way when I last did this. I created separate mattes for the front and back and combined everything in a third action. I believe it was so long ago that action did not have multiple outputs. If I were to do it again I would use projectors similar to @Ton’s method and create a separate matte for the front and back so that I could light the image as I saw fit without regards to whether it spilled to the back or not. I could also build all of the animation in a single action and then comp it all down stream.