how to cut out certain part of the object by compositing

Support Compositing and Post Processing
#1

hi
I want cut out the lower overlapping part of the cube with the sphere so that the backgound image is shown through.
please check attatched .blend.
thanks

Attachments

untitled.blend (677 KB)

#2

Use an ID pass of the sphere as a mask or matte shape, set that as an alpha channel and add it to the cube image alpha.

#3

Hey
ID pass works!
I found Blender wiki ID pass manual.

Thank you

#4

Only drawback is that the ID pass isn’t anti aliased from memory. So it can have a rough edge.

#5

recent build from graphicall.org has anti aliase check box for ID pass node works fine.