// Crowded-line circle, full cap:
// Base grid is independent of the circle. The dense disc is swept
// on its own, from the true top (+radius) to the bottom (-radius),
// so no cap is ever clipped.

// --- line field ---
let half     = 30       // [18:1:32] half-width, mm
let rows     = 50       // [12:1:80] base-line count
let gap      = (half * 2) / rows
let radius   = 22       // [6:1:36] dense-disc radius, mm
let infillsp = 0.6      // [0.3:0.1:1.5] infill chord spacing, mm

stitchlen 2
seed 1

def baseline(ly, d) [
  let x = half
  if d == 1 [ x = -half ]
  up setxy(x, ly) down
  seth 90 * d
  fd half * 2
]

def chordline(yy, d) [
  let hw = sqrt(radius * radius - yy * yy)
  let x = hw
  if d == 1 [ x = -hw ]
  up setxy(x, yy) down
  seth 90 * d
  fd hw * 2
]

// 1) the even base grid across the whole square
let y = half
repeat rows + 1 [
  let dir = 1
  if repcount % 2 == 0 [ dir = -1 ]
  baseline(y, dir)
  y -= gap
  trim
]

// 2) the dense disc, swept on its own from top to bottom
let yy = radius
let d  = 1
while yy > -radius [
  // guard the sqrt: skip the exact rim where hw would be ~0
  if abs(yy) < radius [
    chordline(yy, d)
    d = -d                  // snake the infill too
    trim
  ]
  yy -= infillsp
]