Masking problem

[Brian Charles]

[Dave LaRonde] “We can’t hemp very much without good information.”

Dave, have you moved to Colorado?

[Stig Olsen]

3d layers and pin corner effect. Stig

[Brian Charles]

[stig olsen] “When using the pen tool and masking out the area I want it does not work that way. Other parts of the graphic dissapear instead. I think this has to do with the way I have moved the corners of my layer or something.
I have also tried to precompose the layer to see if I could mask a selected part without experiencing the same problem, but I dont.”

If you are Corner Pinning a 3D layer, try pre-composing but move all attributes to the new comp. Then apply the mask.

[Stig Olsen]

Thank you Brian, I will try that. Why is it behaving this way?

[Brian Charles]

[stig olsen] “Why is it behaving this way?”

After Effects defaults to performing calculations in a certain order.

Just like basic math there is an order to complex operations. In high school I was taught an acronym, BEDMAS as a mnemonic to remember the order. https://math.about.com/od/glossaryofterms/g/What-Is-Bedmas.htm

Operations in brackets are carried out first followed by the remaining operations.

After Effects behaves in a similar fashion. In general, for raster layers, Masks are calculated before Effects which are calculated before Transformations, you can use MET as an acronym to remember the order.

When layers are nested or Pre-Composed, its like placing brackets around any operations (masks, effects, transforms) for those layers, the operations are done before the next ones.

In your case the Mask is processed before the Corner Pin. Pre-Composing the layer with the Corner Pin then applying the mask to the Pre-Comp forces the Corner Pin to process before the Mask.

You might think of Pre-Composing as placing brackets around those operations.

[Stig Olsen]

Perfectly clear, thank you!!! Stig