Cutting holes

- between two shapes is the difference: the region of the left shape outside the right one.

shape plate - window as frame

When the right shape lies inside the left one, the result has a hole. GDSII polygons cannot have holes, so laylight writes it as one polygon with a zero-width cut from the hole to the outer edge, a keyhole.

Either side can also be a list of shapes, which counts as their union:

shape plate - [slot1, slot2] as frame

The order matters for -, unlike for +: window - plate is empty here.

Exercise

Turn the plate into a frame: cut the window out of it and name the result frame. Then cut the two slots out of the frame's left and right sides too, in the same statement, with a list.

import "tech.lyl" # A bond pad: a plate with a window in the middle and a slot on each side. cell Pad { layer metal { shape rect with 60um, 60um as plate shape rect with 30um, 30um as window shape rect with 10um, 4um as slot1 shape rect with 10um, 4um as slot2 place plate at self.origin place window at self.origin place slot1.left_center at plate.left_center place slot2.right_center at plate.right_center } }