// =====================================================================
//  FUNCTIONAL STITCHES — structural embroidery, not decoration
// =====================================================================
//  A sampler of stitches that DO a job: hold seams, take strain,
//  finish raw edges, and open holes that won't fray. Each one is a
//  technique borrowed straight from the sewing room and rebuilt as a
//  reusable NeedleScript procedure you can drop into real work.
//
//  Laid out as a 2x3 grid of stations across the hoop:
//
//     [ bartack ]      [ box-X tack ]     [ eyelet ]
//     [ buttonhole ]   [ blanket edge ]   [ seam: bean+lock ]
//
//  Run it, then scrub the playback to watch each station sew. Toggle
//  the density heatmap — the bartack and box-X are MEANT to run hot;
//  that concentrated thread is the strength.
// =====================================================================

fabric "denim          // stable base that tolerates dense, strong stitching
seed 7
stitchlen 2

// grid geometry: two rows, three columns of stations
// --- sampler layout ---
let colx = -30         // x of the left column
let colstep = 24       // [18:1:30] spacing between columns, mm
let rowy = 22          // [14:1:30] top-row height, mm
let rowstep = 28       // [20:1:34] spacing between rows, mm

//  helper: jump to a station centre without sewing a connector thread
def goto(x, y) [
  up
  setxy(x, y)
  down
]


// =====================================================================
//  1. BARTACK  —  the workhorse reinforcement
// =====================================================================
//  A short, very dense satin block sewn ACROSS a stress point: the
//  ends of a pocket opening, the base of a fly, belt loops, zipper
//  stops. It is just a narrow satin column, kept short and packed
//  tight so the thread itself becomes the structure.
//
//  Real bartacks are sewn in two passes — a looser anchoring pass,
//  then a dense covering pass over the top. We do exactly that.
def bartack(length, width) [
  // pass 1 — anchoring pass, open spacing, tacks the fabric down
  density 0.8
  satin width
  seth 90              // lay the tack horizontally
  fd length
  satin 0

  // pass 2 — covering pass, very dense, back over the same span
  goto(xcor - length, ycor)
  density 0.3          // packed tight: this is where the strength is
  satin width
  seth 90
  fd length
  satin 0
  density 0.4          // restore the default for whatever comes next
]


// =====================================================================
//  2. BOX-X TACK  —  for the corners of patch pockets & strap ends
// =====================================================================
//  A stitched rectangle with both diagonals sewn across it. Spreads
//  load over an area instead of a line — the classic way to anchor a
//  pocket corner or the end of a backpack strap so it can't peel off.
//
//  We bean-stitch the whole figure so every leg is sewn three times:
//  triple the thread, triple the hold.
def boxtack(size) [
  let h = size / 2
  bean 3               // every line sewn 3x — bold and strong

  // trace the box outline
  goto(xcor - h, ycor - h)
  seth 90  fd size     // bottom
  seth 0   fd size     // right
  seth 270 fd size     // top
  seth 180 fd size     // left, closing the box

  // now the two diagonals across it, corner to corner
  seth 45  fd size * sqrt 2       // bottom-left to top-right
  seth 180 fd size                // run along the top edge to the next corner
  seth 315 fd size * sqrt 2       // top-left to bottom-right

  bean 1               // bean off
]


// =====================================================================
//  3. EYELET  —  a hole that won't fray
// =====================================================================
//  A ring of dense satin worked around an opening: lace-up eyelets,
//  drawstring exits, grommet holes. The satin column is bent into a
//  full circle by `arc`, leaving a clean centre for the cord while the
//  packed thread stops the fabric from running.
//
//  Two concentric satin rings make a heavier, grommet-like edge.
def eyelet(radius) [
  density 0.35
  // outer ring
  goto(xcor + radius, ycor)
  seth 0               // tangent to the circle at the start point
  satin 2
  arc 360 radius
  satin 0

  // inner ring, tight against the hole for a reinforced lip
  goto(xcor + radius - 1.5, ycor)
  satin 1.4
  arc 360 radius - 1.5
  satin 0
  density 0.4
]


// =====================================================================
//  4. BUTTONHOLE  —  two satin bars + two end bartacks
// =====================================================================
//  A working buttonhole is a long slot finished so the cut edge can't
//  unravel under the button's pull. Construction: a dense satin bar
//  down each side of the slit, capped at each end by a short bartack
//  running crosswise to stop the ends from splitting.
//
//  `gap` is the slit width (where you'd cut); `length` is the slot.
def buttonhole(length, gap) [
  let half = gap / 2
  density 0.3          // buttonholes are always tightly packed

  // left bar — satin column running the length of the slot
  goto(xcor - half, ycor - length / 2)
  satin 1.6
  seth 0  fd length
  satin 0

  // right bar — back down the other side of the slit
  goto(xcor + half, ycor + length / 2)
  satin 1.6
  seth 180  fd length
  satin 0

  // top bartack — caps the slot end, sewn across the full width
  goto(xcor - half - 1, ycor)
  satin 1.4
  seth 90  fd gap + 2
  satin 0

  // bottom bartack — caps the other end
  goto(xcor - half - 1, ycor - length)
  satin 1.4
  seth 90  fd gap + 2
  satin 0

  density 0.4
]


// =====================================================================
//  5. BLANKET EDGE  —  finishing a raw edge so it can't fray
// =====================================================================
//  Blanket stitch (`estitch`) throws perpendicular prongs to the left
//  of travel — exactly the edging used to bind blankets, felt applique,
//  and raw seam allowances. Walk it along the edge you want to lock
//  down and the prongs wrap the rim.
//
//  Here we finish the rim of a small disc to show the bound edge.
def blanketedge(radius) [
  goto(xcor + radius, ycor)
  seth 0               // start tangent so prongs point outward along the rim
  estitch 3            // 3 mm prongs, spaced by stitchlen
  arc 360 radius
  estitch 0
]


// =====================================================================
//  6. REINFORCED SEAM  —  bean-stitched run that locks at both ends
// =====================================================================
//  Sometimes the structural job is just "join two things and don't let
//  go." A bean stitch sews each step three times for a thick, secure
//  line — far stronger than a single running stitch — and `lock` ties
//  the ends so nothing can pull free. This is your go-to topstitch for
//  load-bearing seams.
def reinforcedseam(length) [
  lock 1.2             // beefy tie-in / tie-off at the ends of the run
  bean 3               // each stitch sewn 3x — a strong, bold seam line
  goto(xcor, ycor - length / 2)
  seth 0  fd length
  bean 1
  lock 0.7             // back to the default lock size
]


// =====================================================================
//  THE SAMPLER  —  sew all six stations on the grid
// =====================================================================

// top row:
color 1

goto(colx, rowy)
bartack(12, 2.5)                       // station 1: bartack
trim

goto(colx + colstep, rowy)
boxtack(14)                            // station 2: box-X tack
trim

goto(colx + colstep * 2, rowy)
eyelet(5)                              // station 3: eyelet
trim

// bottom row:
color 2

goto(colx, rowy - rowstep)
buttonhole(16, 3)                      // station 4: working buttonhole
trim

goto(colx + colstep, rowy - rowstep)
blanketedge(9)                         // station 5: blanket-bound edge
trim

goto(colx + colstep * 2, rowy - rowstep)
reinforcedseam(18)                     // station 6: reinforced seam
trim

//  Try next:
//   - bump `density` lower (0.25) on the bartack pass-2 for even more
//     thread — watch the heatmap go red where the strength lives.
//   - chain bartacks along a line to reinforce a long pocket mouth.
//   - wrap any station in `scale 1.4 [ ... ]` to resize it; the satin
//     spacing stays physical, so the reinforcement density is preserved.