I realise this is an oldish thread, but it should now be possible wth new shaders/filters to create 3D Anaglyph pictures or game elements.
Cyan layer 000 255 255
Red layer 255 000 000
1, Set Cyan layer transfer mode to screen.
2, Merge Cyan and left photo.
3, Set Red layer transfer mode to screen.
4, Set the merged Cyan and left photo layer transfer mode to multiply.
Anaglyph should be visible through 3D glasses.Test