---
title: sa
---
The `sa` macro will create seam allowance paths.
Unlike the core `path.join(...)` and `path.offset(...)` functions, the `sa` macro can extend line ends to meet in a sharp corner and will automatically
trim useless path ends when adjacent paths in the array are intersecting.
The sa macro accepts an array of `Path` objects
(either names in the `paths` array or direct references to `Path` objects).
This array can contain `null` values to create gaps (e.g. for cuts on the fold or for other sections that don't need seam allowance).
By default, the `sa` macro will sa the paths in a circular fashion, joining the end
of the last path in the array to the start of the first path, creating a full outline.
If this is not desired, insert `null` elements where you want to create gaps.
You can optionally override the offset and invisibility for individual paths.
To do so, insert an object literal like `{p: 'somePath', offset: 30}` or `{p: ['path1', 'path2'], offset: sa * 3, hidden: true}` into the `paths` array.
You can use `offset: 0` to include paths which have already build-in the seam allowance (e.g. the result of the `hem` macro).
You can use `hidden: true` to hide path segments from the output, but still build corner joins as if they were there.
This can be used for cut-on-fold lines, where no seam allowance is needed.
## Signature
```js
macro('sa', {
Array paths,
number limit,
string mode,
string class
})
```
## Example
<Example caption="An example of the sa macro">
```js
;({ Point, points, Path, paths, macro, part }) => {
paths.outline = new Path()
.move(new Point(10, 30))
.line(new Point(30, 30))
.line(new Point(30, 50))
.line(new Point(50, 50))
.line(new Point(50, 70))
.line(new Point(70, 70))
.curve(new Point(55, 15), new Point(55, 15), new Point(30, 0))
paths.outline2 = new Path().move(new Point(30, 0)).line(new Point(10, 30))
paths.sa = macro('sa', {
paths: ['outline', { p: 'outline2', offset: 30 }],
sa: 10,
}).setClass('stroke-sm mark dotted')
paths.halfCircle = new Path().move(new Point(100, 0)).circleSegment(37, new Point(200, 0)).hide()
paths.halfCircleClosed = paths.halfCircle.clone().line(new Point(200, 0)).unhide().close()
paths.halfCircleSa = macro('sa', {
paths: ['halfCircle', null],
sa: 10,
}).setClass('stroke-sm mark dotted')
return part
}
```
</Example>
## Configuration
| Property | Default | Type | Description |
| -------: | ---------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `paths` | | `array` | An array of paths. You can use path names in the `paths` array or reference `Path` objects directly, or insert `null` elements to create gaps. You can also override offset and visibility for individual paths in the same way as with the `offset` macro. |
| `mode` | `'corner'` | `string` | Mode for joining paths. Either `'corner'` or `'cut'`. `'cut'` will join the paths directly (like `path.join(...)`) without extending the corners. |
| `limit` | `null` | `number` | Allows limiting the length of extended path corners in `'corner'` mode. Prevents overly long joins on very sharp angles. Ignored if `null` or `false`. |
| `sa` | (seam allowance) | `number` | Allows you to override the seam allowance used for this macro. Defaults to the standard seam allowance (`sa` parameter in draft function). |
| `class` | `'sa'` | `string` | CSS class that is automatically applied to the resulting path. |
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