Mapping matrix displays

6

Hi folks,
A bit late to the party, but I had an unusual arrangement of 8x8 panels and needed to map them. I came up with this system, which should allow all kinds of arbitrary arrangements of these or other panels of any width, height, and including rotations!

function (pixelCount) {
  //enable zigzag if every other LED row travels in reverse
  //if they are all straight across, disable it
  zigzag = true
  
  //roate a point (x, y), along a center (cx, cy), by an angle in degrees
  function rotate(cx, cy, x, y, angle) {
    var radians = (Math.PI / 180) * angle,
        cos = Math.cos(radians),
        sin = Math.sin(radians),
        nx = (cos * (x - cx)) + (sin * (y - cy)) + cx,
        ny = (cos * (y - cy)) - (sin * (x - cx)) + cy;
    return [nx, ny];
  }

  //create a set of coordinates for a matrix panel
  // sized (w, h), rotated by an angle, and offset by (sx, sy)
  function panel(w, h, sx, sy, angle) {
    var x, x2, y, p, map = []
    for (y = 0; y < h; y++) {
      for (x = 0; x < w; x++) {
        //for zigzag, flip direction every other row
        if (zigzag && y % 2 == 1)
          x2 = w - 1 - x
        else
          x2 = x
        p = rotate((w-1)/2, (h-1)/2, x2, y, angle);
        p[0] += sx
        p[1] += sy
        map.push(p)
      }
    }
    return map;
  }

  //assemble one or more panels
  var map = [];

  map = map.concat(panel(8, 8, 0, 0, 0))
  map = map.concat(panel(8, 8, 0, 8, 0))
  map = map.concat(panel(8, 8, 8, 8, 0))
  map = map.concat(panel(8, 8, 8, 0, 0))

  return map
}

Here’s my funky panel map in action:

Nov-04-2020 12-16-10

In this kind of setup:

1 4
2 3

The rotation is really only intended to work with 90° increments, it positions the panels from the top left corner before rotation along the center. However, these helper functions could be adapted for arbitrary angles and positioning.

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