show a different image on the back of a 3d object with curvature

[Rebecca_IDW]

I am trying to create a page turn without using the cc page turn effect (i don't like how it looks for this animation). I have my page set to animate as a 3d layer with curvature applied, and i want to show the next page on the back of it as it flips.  i found a way to do this using the blend effect, putting the following expresion in "blend with original": toCompVec([0, 0, 1])[2] > 0 ? value : 0

The problem is that with the curvature, as the page flips, it doesn't show me the alternate image until it actually crosses the gutter of the book - until that point, it shows the image that's on the front of the page on the back side.  I know there's a way to fix this, and I'm almost there.  Does anyone have an answer?

This is what it's showing:

I want to show the next page on the back: 

Thank you!

[Jose Panadero]

I cannot see your composition and the way you are working. Maybe you can try to precompose those layers with a very little offset in z position (pages) and using the collapse transformation option in the main comp. Not sure but you can try it.

Anyway I think this AE is not the best way to do what you are trying to achieve. With your AE suscription, you have a Cinema 4D Lite bundled (Layer > New > Maxon Cinema 4D File...). This way is a lot easier to create planes that bend in 3D using the included Bend deformer.

[Mylenium]

Nothing to fix because nothing is broken. The functionality you seek cannot be had with any expression. Expressions modulate property streams, they don't evaluate shaders as you would require. As already suggested move on to "real" 3D by ways of Cinema 4D. At least there you can control whether a texture appears on thze front or back or both sides.

Mylenium

[Rebecca_IDW]

Thank you Jose_Pandero and Mylenium - I will try using Cinema 4D.