Edges

Contours and edge pairs. For extended, in is the left normal of the edge (the interior of a counter-clockwise hull).

← Language overview

`edges(a)`

Available · yields edges

layer e = edges(a)

Each contour segment as an open edge. A closed ring is not doubled (the last=first point is omitted once). Zero length (a==b) is skipped.

Notes

An empty polygon / fewer than 2 points: no edges.
A hole: edges of the hole ring and of the hull — orientation stays as stored (hole clockwise).
Edge pairs as input: both edges of the pair, not the distance.
Already edges: identity.

`first_edges(p)`

Available · yields edges

layer e1 = first_edges(width(m1) < 0.14 um)

First edge of each edge pair (e1). From polygons: falls back to edges() (the whole contour).

Notes

An empty pair list: empty.
The dummy marker of empty / count: edge (0,0)-(1,0).
second_edges is the same for e2 — for width, e2 is the opposite edge.

`second_edges(p)`

Available · yields edges

layer e2 = second_edges(p)

Second edge of each pair.

Notes

Same as first_edges, other side.
A degenerate pair (point marker from ongrid): e2 identical to e1 (a point edge).

`extended(e, d)`

Available · yields polygons

layer p = extended(e, 0.05 um)

Each edge becomes a quad: out and in each d. in = left normal (-uy, ux); on a CCW hull that is the interior. Then merged().

Also written as: extended(e, out=d, in=d)

Notes

All four lengths 0: empty (not the original).
A zero-length edge is skipped.
Only out (extended_out / in=0): a band outside; on the inner edge of a hole, in points into the metal.
begin / end extend tangentially at the start or end — they can run past corners and overlap neighbour bands, then merge.
Quad corners are rounded to whole dbu; very skew edges can get a 1 dbu stair.

`extended_out / extended_in`

Available · yields polygons

layer o = extended_out(e, 0.05 um)
layer i = extended_in(e, 0.05 um)

Short forms for extended(e, out=d, in=0) and out=0, in=d. Full form: extended(e, out=…, in=…, begin=…, end=…).

Also written as: extended(e, out=d, in=0)

Notes

One side 0: the quad still has the width of the other side; both 0 and begin/end 0: empty.
A negative out/in reverses the direction (the sign is used, not the absolute value).

`start_segments / end_segments / centers`

Available · yields edges

layer s = start_segments(e, 0.2 um)

Part of the edge from the start, from the end, or a middle piece of length d. Polygons become edges first.

Notes

d = 0 or a degenerate edge: no piece.
d longer than the edge: clamp to the full edge.

`corners(a)`

Available · yields polygons / edges

layer c = corners(a)
layer c = corners(a, 80, 100)

Corners as 2×2 dbu boxes, optionally with an interior-angle window (absolute turn).

Notes

180° (collinear): angle 0; without a window still a point, with a window often dropped.
The angle window is the same idea as with_angle.

`bbox_center(a)`

Available · yields polygons / edges

layer c = bbox_center(a)

Centre of the shape bounding box as a 2×2 dbu box (anchor).

Notes

One shape → one marker. Integer centre: (min+max)/2.
An empty layer: empty.

`intersections(e1, e2)`

Available · yields edges / points

layer p = intersections(e1, e2)

Proper crossings of two edge layers as 2×2 dbu boxes. Endpoints on the other edge do not count (open interval).

Notes

Parallel without overlap: empty.
Collinear overlap: no crossing in this kernel.
A T-junction (endpoint on an edge): currently no hit.

`with_edge(a, b)`

Available · yields polygons

layer w = with_edge(a, b)

A-shapes that have at least one collinear edge piece on B. B is converted to edges if needed.

Notes

Only a shared vertex without an edge piece: no.
A completely in B without a shared contour edge: no.

`polygons(x)`

Available · yields polygons

layer p = polygons(width(m1) < 0.14 um)
layer p = polygons(e, 0.02 um)

Edge pairs → quadrilateral e1.a–e1.b–e2.b–e2.a. Fewer than 3 unique points: a 2×2 dbu box around the point. Optional second argument: then sized(d).

Notes

An edge layer instead of pairs: a 1 dbu tube.
Already polygons: identity, plus optional sized.
Opposite pair orientation can produce a rotated or crossed quad; the area can be almost 0.