# ============================================================================
# atlas.ludic — render a Kenney tile pack as one index-labeled sheet, so you can
# see which sprite id is which before referring to it in a game.
#
#   ludicc tools/atlas.ludic --headless -o build/atlas
#   ./build/atlas && sips -s format png out.ppm --out atlas.png
#
# Replaces the old tools/atlas.c, which used the C runtime that no longer
# exists. It is the same program, in the language it is a tool for.
# ============================================================================
game Atlas {
  const DIR:  str = "assets/kenney/tiny-dungeon/Tiles"
  const N:    int = 132
  const COLS: int = 12
  const CELL: int = 24

  system Sheet phase Start {
    clear(0x101018)
    for i in 0 .. N {
      let col = i % COLS
      let row = i / COLS
      let x = col * CELL
      let y = row * CELL
      # tile_0000.png … tile_0131.png — the id is the file's number
      let id = load_png(tile_path(i))
      if id >= 0 {
        draw_sprite(id, x + 4, y + 2)
      }
      text_int(x + 1, y + 18, i, 0x8090b0, 1)
    }
    present()
    quit()
  }

  # build "<DIR>/tile_%04d.png" without a formatter: the runtime's string
  # helpers write into a scratch buffer we own
  function tile_path(i: int) -> string {
    let buf = atlas_buf()
    let n = rt_put_str(buf, 0, DIR)
    n = rt_put_str(buf, n, "/tile_")
    if i < 1000 { poke8(buf, n, 48)  n = n + 1 }
    if i < 100 { poke8(buf, n, 48)  n = n + 1 }
    if i < 10 { poke8(buf, n, 48)  n = n + 1 }
    n = rt_put_int(buf, n, i)
    n = rt_put_str(buf, n, ".png")
    poke8(buf, n, 0)
    return buf
  }

  var atlas_scratch: pointer = ptr_null()

  function atlas_buf() -> pointer {
    if ptr_is_null(atlas_scratch) { atlas_scratch = mem_alloc(512) }
    return atlas_scratch
  }
}