freesewing/packages/examples/src/utils_splitcurve.js

export default part => {
  let { Point, points, Path, paths, utils } = part.shorthand();

  points.from = new Point(40, 10);
  points.to = new Point(40, 80);
  paths.line = new Path()
    .move(points.from)
    .line(points.to)
    .attr("class", "lining dashed");

  points.start = new Point(10, 15);
  points.cp1 = new Point(80, 10);
  points.cp2 = new Point(-50, 80);
  points.end = new Point(110, 70);

  points.i40 = utils.curveIntersectsX(
    points.start,
    points.cp1,
    points.cp2,
    points.end,
    40
  );

  let parts = utils.splitCurve(
    points.start,
    points.cp1,
    points.cp2,
    points.end,
    points.i40
  );

  let colors = ["lining", "interfacing"];
  for (let p of parts) {
    let color = colors.pop();
    paths[color] = new Path()
      .move(p.start)
      .curve(p.cp1, p.cp2, p.end)
      .attr("class", "stroke-xl " + color);
  }

  return part;
};