@thi.ng/geom-axidraw/as-geometry.js

Conversion and preparation of thi.ng/geom shapes & shape groups to/from AxiDraw pen plotter draw commands

import { group } from "@thi.ng/geom/group";
import { points } from "@thi.ng/geom/points";
import { polyline } from "@thi.ng/geom/polyline";
import { add2 } from "@thi.ng/vectors/add";
import { copy } from "@thi.ng/vectors/copy";
const DEFAULT_ATTRIBS = {
  paths: { stroke: "#000" },
  rapids: { stroke: "#0ff" },
  ups: { fill: "#0f0", stroke: "none" },
  downs: { fill: "#f00", stroke: "none" }
};
const asGeometry = (src, opts = {}) => {
  opts = {
    rapids: true,
    pen: true,
    ...opts,
    attribs: { ...DEFAULT_ATTRIBS, ...opts.attribs }
  };
  const rapids = [];
  const paths = [];
  const downs = [];
  const ups = [];
  let penDown = false;
  let pts = null;
  let currPos = [0, 0];
  const $move = (newPos) => {
    if (penDown || opts.rapids) {
      if (!pts) pts = [copy(currPos), newPos];
      else pts.push(newPos);
    }
    currPos = newPos;
  };
  for (const cmd of src) {
    switch (cmd[0]) {
      // absolute
      case "M":
        $move(copy(cmd[1]));
        break;
      // relative
      case "m":
        $move(add2([], currPos, cmd[1]));
        break;
      case "u":
        if (pts) {
          if (penDown) paths.push(pts);
          else if (opts.rapids) rapids.push(pts);
          pts = null;
        }
        if (opts.pen) ups.push(copy(currPos));
        penDown = false;
        break;
      case "d":
        if (pts) {
          if (!penDown) {
            if (opts.rapids) rapids.push(pts);
          } else paths.push(pts);
          pts = null;
        }
        if (opts.pen) downs.push(copy(currPos));
        penDown = true;
        break;
      case "home":
        currPos = [0, 0];
        if (!pts) pts = [currPos];
        else pts.push(currPos);
        break;
      default:
        console.log("skipping command", cmd);
    }
  }
  if (pts) {
    if (penDown) paths.push(pts);
    else rapids.push(pts);
  }
  return {
    paths: group(
      opts.attribs.paths,
      paths.map((pts2) => polyline(pts2))
    ),
    rapids: group(
      opts.attribs.rapids,
      rapids.map((pts2) => polyline(pts2))
    ),
    ups: points(ups, opts.attribs.ups),
    downs: points(downs, opts.attribs.downs)
  };
};
export {
  asGeometry
};