Use different objects to mark overlapping object outlines

[samytichadou]

Hi i would like to mark (through lines or rim light) overlapping outlines between 2 separate objects.

Here is a screenshot :

My goal is to get malt to generate the yellow lines automatically.
I am struggling with getting this kind of effect, i am trying to use object ID with pre pass, but i'm still unclear with the how (new user here, sorry if dumb question :) )

Does anyone out here has an idea ? cheers !

[pragma37]

You could set the Custom ID A to (0,0,0,0) (the same as the background) for the red shape and to something else for the blue shape.
Then if you use a Line Width node to the red shape where all Widths are 0 except for the second channel of ID Boundary Width that should get you the result you want.