retransfer_grid

const DPI = 600;
const MM_PER_IN = 25.4;

// === RETRANSFER CANVAS (source of truth) ===
const TOTAL_W = 2100;
const TOTAL_H = 1344;

// === PHYSICAL CARD SIZE (ISO ID-1) ===
const CARD_W_MM = 85.6;
const CARD_H_MM = 54;

// convert card size to pixels at 600 dpi
const CARD_W = Math.round(CARD_W_MM * DPI / MM_PER_IN);
const CARD_H = Math.round(CARD_H_MM * DPI / MM_PER_IN);

// centered trim area (actual card)
const CARD_X = Math.round((TOTAL_W - CARD_W) / 2);
const CARD_Y = Math.round((TOTAL_H - CARD_H) / 2);

function setup() {
  createCanvas(TOTAL_W, TOTAL_H);
  pixelDensity(1);
  noLoop();
}

function draw() {
  background(255);

  // outer canvas (retransfer film)
  noFill();
  stroke(0);
  rect(0, 0, TOTAL_W, TOTAL_H);

  // actual card trim area
  strokeWeight(5);
  rect(CARD_X, CARD_Y, CARD_W, CARD_H);

  const cols = 10;
  const rows = 6;
  const cell_w = CARD_W / cols;
  const cell_h = CARD_H / rows;

  // grid inside card area
  for (let i = 0; i < cols; i++) {
    const x = CARD_X + i * cell_w;
    line(x, CARD_Y, x, CARD_Y + CARD_H);
  }
  for (let j = 0; j < rows; j++) {
    const y = CARD_Y + j * cell_h;
    line(CARD_X, y, CARD_X + CARD_W, y);
  }

  // example center mark
  strokeWeight(8);
  stroke(255, 0, 0);
  strokeCap(ROUND);

  const line_len = CARD_H / 3;
  const cx = TOTAL_W / 2;
  const cy = TOTAL_H / 2;

  // example cross (optional)
  // line(cx, cy, cx + line_len, cy);
  // line(cx, cy, cx, cy - line_len);

  saveCanvas('id_test', 'tiff');
}