add_route_from_steps is the relative-coordinate sibling of add_route_from_corners. Instead of giving absolute (x, y) corner points, you describe each leg of the route as a one-axis step. The big advantage: the same step recipe works at any placement, so it's a natural way to write reusable routing patterns.

Each step contributes one corner. The four supported forms are:

Interior steps must use exactly one axis (horizontal or vertical). The first and last steps may combine both axes to set the fan-in/out anchor.

This is optical routing: bends are bend_euler at the PDK minimum radius (5 µm for cspdk.si220.cband).

Imports

import doroutes as dr
import gdsfactory as gf
from cspdk.si220.cband import PDK

PDK.activate()

Z-Detour Described as Steps

The same field1 layout, routed with a step recipe that mixes relative and absolute moves and ends by anchoring the y-coordinate to the output port directly.

c = gf.Component()
ref = c << dr.pcells.field1()

start = ref.cell.insts["in"].ports["o2"]
stop = ref.cell.insts["out"].ports["o1"]
stop_pos = dr.types.validate_position(stop)

steps = [
    {"dx": 41500},  # head east 41.5 µm from the input
    {"dy": 32500},  # turn north 32.5 µm
    {"x": 2000},  # turn west, land at absolute x = 2 µm
    {"y": stop_pos[1]},  # turn north, land at the y of the output port
]

dr.add_route_from_steps(
    c=c,
    start=start,
    stop=stop,
    steps=steps,
    straight="straight",
    bend={"component": "bend_euler", "settings": {"radius": 5}},
)
dr.util.show_cell(c)

Next steps

• Prefer absolute corner points? See Corners Routing.
• The bundle version of this routing style is add_bundle_from_corners(steps=...), demonstrated in Array Routing.
• For obstacle-aware routing without writing the shape yourself, see A* Single Route.