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.

note

Not a core-plugins macro

The sa macro is not provided by the core plugins, so you need to load the path-utils plugin explicitly if you want to use it.

Signature

macro('sa', {
  Array paths,
  number limit,
  string mode,
  string class
})

Example

Preview

Code

({ 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
}

X-Ray

An example of the sa macro

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.

Notes

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.