freesewing/markdown/dev/tutorials/pattern-design/en.md

---
title: Pattern design tutorial
---

Welcome to the FreeSewing pattern design tutorial, where we'll learn how to
design a made-to-measure sewing pattern, start to finish.

<Tip>
##### Before you start

If you haven't done so yet, read the [Before you start
guide](/guides/prerequisites). It's very short, but covers some basic
terminology and concepts that we'll use throughout this guide.
</Tip>

We will be designing a pattern for a baby bib. It's a very simple pattern, but
that's the point.  Our focus today is on learning FreeSewing and how to
translate our designs into code.

At the end of this tutorial, we will have created this pattern:


<Example tutorial="1" previewFirst="1" caption="Our end result">
```design/src/bib.mjs
function draftBib({
  Path,
  Point,
  paths,
  points,
  measurements,
  options,
  macro,
  complete,
  snippets,
  Snippet,
  part,
}) {

  // Construct the quarter neck opening
  let tweak = 1
  let target = (measurements.head * options.neckRatio) /4
  let delta
  do {
    points.right = new Point(tweak * measurements.head / 10, 0)
    points.bottom = new Point(0, tweak * measurements.head / 12)

    points.rightCp1 = points.right.shift(90, points.bottom.dy(points.right)/2)
    points.bottomCp2 = points.bottom.shift(0, points.bottom.dx(points.right)/2)

    paths.quarterNeck = new Path()
      .move(points.right)
      .curve(points.rightCp1, points.bottomCp2, points.bottom)
      .hide() // Add this line

    delta = paths.quarterNeck.length() - target
    if (delta > 0) tweak = tweak * 0.99
    else tweak = tweak * 1.02
  } while (Math.abs(delta) > 1)

  // Construct the complete neck opening
  points.rightCp2 = points.rightCp1.flipY()
  points.bottomCp1 = points.bottomCp2.flipX()
  points.left = points.right.flipX()
  points.leftCp1 = points.rightCp2.flipX()
  points.leftCp2 = points.rightCp1.flipX()
  points.top = points.bottom.flipY()
  points.topCp1 = points.bottomCp2.flipY()
  points.topCp2 = points.bottomCp1.flipY()

  // Drawing the bib outline
  const width = measurements.head * options.widthRatio
  const length = measurements.head * options.lengthRatio

  points.topLeft = new Point(
    width / -2,
    points.top.y - (width / 2 - points.right.x)
  )
  points.topRight = points.topLeft.shift(0, width)
  points.bottomLeft = points.topLeft.shift(-90, length)
  points.bottomRight = points.topRight.shift(-90, length)

  // Shape the straps
  points.edgeLeft = new Point(points.topLeft.x, points.left.y)
  points.edgeRight = new Point(points.topRight.x, points.right.y)
  points.edgeTop = new Point(0, points.topLeft.y)

  points.edgeLeftCp = points.edgeLeft.shiftFractionTowards(points.topLeft, 0.5)
  points.edgeRightCp = points.edgeLeftCp.flipX()
  points.edgeTopLeftCp = points.edgeTop.shiftFractionTowards(
    points.topLeft,
    0.5
  )
  points.edgeTopRightCp = points.edgeTopLeftCp.flipX()

  // Round the straps
  const strap = points.edgeTop.dy(points.top)

  points.tipRight = points.edgeTop.translate(strap / 2, strap / 2)
  points.tipRightTop = new Point(points.tipRight.x, points.edgeTop.y)
  points.tipRightBottom = new Point(points.tipRight.x, points.top.y)

  macro("round", {
    from: points.edgeTop,
    to: points.tipRight,
    via: points.tipRightTop,
    prefix: "tipRightTop",
  })
  macro("round", {
    from: points.tipRight,
    to: points.top,
    via: points.tipRightBottom,
    prefix: "tipRightBottom",
  })
  const rotateThese = [
    "edgeTopLeftCp",
    "edgeTop",
    "tipRight",
    "tipRightTop",
    "tipRightTopStart",
    "tipRightTopCp1",
    "tipRightTopCp2",
    "tipRightTopEnd",
    "tipRightBottomStart",
    "tipRightBottomCp1",
    "tipRightBottomCp2",
    "tipRightBottomEnd",
    "tipRightBottom",
    "top",
    "topCp2"
  ]
  while (points.tipRightBottomStart.x > -1) {
    for (const p of rotateThese) points[p] = points[p].rotate(1, points.edgeLeft)
  }

  // Snap anchor
  points.snapLeft = points.top.shiftFractionTowards(points.edgeTop, 0.5)

  // Add points for second strap
  points.edgeTopRightCp = points.edgeTopLeftCp.flipX()
  points.topCp1 = points.topCp2.flipX()
  points.tipLeftTopStart = points.tipRightTopStart.flipX()
  points.tipLeftTopCp1 = points.tipRightTopCp1.flipX()
  points.tipLeftTopCp2 = points.tipRightTopCp2.flipX()
  points.tipLeftTopEnd = points.tipRightTopEnd.flipX()
  points.tipLeftBottomStart = points.tipRightBottomStart.flipX()
  points.tipLeftBottomCp1 = points.tipRightBottomCp1.flipX()
  points.tipLeftBottomCp2 = points.tipRightBottomCp2.flipX()
  points.tipLeftBottomEnd = points.tipRightBottomEnd.flipX()
  points.snapRight = points.snapLeft.flipX()

  // Round the bottom corners
  macro("round", {
    from: points.topLeft,
    to: points.bottomRight,
    via: points.bottomLeft,
    radius: points.bottomRight.x / 4,
    prefix: "bottomLeft"
  })
  macro("round", {
    from: points.bottomLeft,
    to: points.topRight,
    via: points.bottomRight,
    radius: points.bottomRight.x / 4,
    prefix: "bottomRight"
  })

  // Create one path for the bib outline
  paths.seam = new Path()
    .move(points.edgeLeft)
    .line(points.bottomLeftStart)
    .curve(points.bottomLeftCp1, points.bottomLeftCp2, points.bottomLeftEnd)
    .line(points.bottomRightStart)
    .curve(points.bottomRightCp1, points.bottomRightCp2, points.bottomRightEnd)
    .line(points.edgeRight)
    .curve(points.edgeRightCp, points.edgeTopRightCp, points.tipLeftTopStart)
    .curve(points.tipLeftTopCp1, points.tipLeftTopCp2, points.tipLeftTopEnd)
    .curve(points.tipLeftBottomCp1, points.tipLeftBottomCp2, points.tipLeftBottomEnd)
    .curve(points.topCp1, points.rightCp2, points.right)
    .curve(points.rightCp1, points.bottomCp2, points.bottom)
    .curve(points.bottomCp1, points.leftCp2, points.left)
    .curve(points.leftCp1, points.topCp2, points.tipRightBottomEnd)
    .curve(points.tipRightBottomCp2, points.tipRightBottomCp1, points.tipRightBottomStart)
    .curve(points.tipRightTopCp2, points.tipRightTopCp1, points.tipRightTopStart)
    .curve(points.edgeTopLeftCp, points.edgeLeftCp, points.edgeLeft)
    .close()
    .addClass("fabric")

  if (complete) {
    // Add snaps
    points.snapLeft = points.top
      .shiftFractionTowards(points.edgeTop, 0.5)
    points.snapRight = points.snapLeft.flipX()
    snippets.snapStud = new Snippet('snap-stud', points.snapLeft)
    snippets.snapSocket = new Snippet('snap-socket', points.snapRight)
      .attr('opacity', 0.5)

    // Add a logo
    points.logo = new Point(0, 0)
    snippets.logo = new Snippet("logo", points.logo)

    // Add a title
    points.title = points.bottom.shift(-90, 45)
    macro("title", {
      at: points.title,
      nr: 1,
      title: "bib",
      scale: 0.7
    })

    // Add a scalbox
    points.scalebox = points.title.shift(-90, 55)
    macro("scalebox", { at: points.scalebox })

    paths.bias = paths.seam
      .offset(-5)
      .addClass("various dashed")
      .addText("finishWithBiasTape", "center fill-various")

  }

  return part
}
```
</Example>

Before we can get started, let's make sure we have the required software
installed on our computer:

## Prerequisites

FreeSewing is a JavaScript library that can run in the browser, on
[Node.js](https://nodejs.org/), or a variety of other runtimes such as Deno,
AWS Lambda, and so on.

For development, we'll use Node.js. If we don't have Node.js on our system,
follow the link above and install it on our system.

<Tip compact>We need Node.js 16 or higher to use FreeSewing</Tip>

When we're done, we can test whether it works by running:

```sh
node -v
```

If we get the Node.js version number, we're all set.