How to create nested cells using gdstk

[GaN-T]

How do I create a heirarchial cell structure in gdstk when viewing the file in Klayout? The example of cell references in the documentation results in independent cells appearing in the viewer cell tree.

import gdstk
import numpy as np

lib = gdstk.Library()
# Layer/datatype definitions for each step in the fabrication
ld = {
    "full etch": {"layer": 1},
    "partial etch": {"layer": 2},
    "lift-off": {"layer": 0},
}

p1 = gdstk.rectangle((-3, -3), (3, 3), **ld["full etch"])
p2 = gdstk.rectangle((-5, -3), (-3, 3), **ld["partial etch"])
p3 = gdstk.rectangle((5, -3), (3, 3), **ld["partial etch"])
p4 = gdstk.regular_polygon((0, 0), 2, 6, **ld["lift-off"])

# Create a cell with a component that is used repeatedly
contact = lib.new_cell("CONTACT")
contact.add(p1, p2, p3, p4)

cutout = gdstk.Polygon(
    [(0, 0), (5, 0), (5, 5), (0, 5), (0, 0), (2, 2), (2, 3), (3, 3), (3, 2), (2, 2)]
)
# Create a cell with the complete device
device = lib.new_cell("DEVICE")
device.add(cutout)
# Add 2 references to the component changing size and orientation
ref1 = gdstk.Reference(contact, (3.5, 1), magnification=0.25)
ref2 = gdstk.Reference(contact, (1, 3.5), magnification=0.25, rotation=np.pi / 2)
device.add(ref1, ref2)

# The final layout has several repetitions of the complete device
main = lib.new_cell("MAIN")
main.add(gdstk.Reference(device, (0, 0), columns=3, rows=2, spacing=(6, 7)))

# lib.add(main)
lib.write_gds("test.gds")

How do we achieve a nested structure e.g. shown here

[Rishabhgoyal07]

@GaN-T, you have to reference the cells in the main cell to create nested cell.

[GaN-T]

Could you please show how the example code I gave in my post would be modified to achieve this?

[Rishabhgoyal07]

in the *lib.add(main,main.dependencies(True)**), this will add all the dependencies of the referenced cell, and all the cells will be shown with their hierarchy

[GaN-T]

this didn't change the output from the example I initially provided referencing the "Getting started" documentation. The heirarchy is there, it is just not shown in the KLayout Cell viewer. Please see this link for an example of what I am trying to do

[Rishabhgoyal07]

paste your klayout screenshot

[GaN-T]

It doesn't appear as a nested tree like I want even though the hierarchy is present in the layout. When I flatten cell list I can see the components in the list too, but as individual cells, not nested below main.

import gdstk
import numpy as np

lib = gdstk.Library()
# Layer/datatype definitions for each step in the fabrication
ld = {
    "full etch": {"layer": 1},
    "partial etch": {"layer": 2},
    "lift-off": {"layer": 0},
}

p1 = gdstk.rectangle((-3, -3), (3, 3), **ld["full etch"])
p2 = gdstk.rectangle((-5, -3), (-3, 3), **ld["partial etch"])
p3 = gdstk.rectangle((5, -3), (3, 3), **ld["partial etch"])
p4 = gdstk.regular_polygon((0, 0), 2, 6, **ld["lift-off"])

# Create a cell with a component that is used repeatedly
contact = lib.new_cell("CONTACT")
contact.add(p1, p2, p3, p4)

cutout = gdstk.Polygon(
    [(0, 0), (5, 0), (5, 5), (0, 5), (0, 0), (2, 2), (2, 3), (3, 3), (3, 2), (2, 2)]
)
# Create a cell with the complete device
device = lib.new_cell("DEVICE")
device.add(cutout)
# Add 2 references to the component changing size and orientation
ref1 = gdstk.Reference(contact, (3.5, 1), magnification=0.25)
ref2 = gdstk.Reference(contact, (1, 3.5), magnification=0.25, rotation=np.pi / 2)
device.add(ref1, ref2)

# The final layout has several repetitions of the complete device
main = lib.new_cell("MAIN")
main.add(gdstk.Reference(device, (0, 0), columns=3, rows=2, spacing=(6, 7)))

lib.add(main, *main.dependencies(True))
lib.write_gds("test.gds")

Could you post your output?

[nmz787-intel]

Using the original/first post code, I get this output

You may need to right-click the cell list, and then uncheck "Flat Cell List"

You may also notice that you can select which cell you want to start viewing the hierarchy from, with the so-called "Show As New Top"

[GaN-T]

Thanks this is exactly it!