invaders_print.py

#!/usr/bin/env python3
"""Print a grid of random pixel-art invaders on the S01 thermal printer.

Each invader is a small mirror-symmetric sprite generated by randomly filling
half its cells and reflecting -- the same trick behind GitHub identicons and
Space Invaders. Every seed is a fresh swarm.

Examples:
    python invaders_print.py                  # 4x6 swarm
    python invaders_print.py --cols 5 --rows 7
    python invaders_print.py --size 7         # chunkier sprites
    python invaders_print.py --seed 1234
    python invaders_print.py --no-print
"""
from __future__ import annotations

import argparse
from pathlib import Path
import random

from PIL import Image, ImageDraw

from print_common import ROOT, Card


def draw_invader(rng: random.Random, size: int, cell: int) -> Image.Image:
    half = (size + 1) // 2
    grid = [[0] * size for _ in range(size)]
    for r in range(size):
        for c in range(half):
            on = 1 if rng.random() < 0.5 else 0
            grid[r][c] = on
            grid[r][size - 1 - c] = on  # mirror left -> right
    img = Image.new("L", (size * cell, size * cell), 255)
    d = ImageDraw.Draw(img)
    for r in range(size):
        for c in range(size):
            if grid[r][c]:
                d.rectangle((c * cell, r * cell, c * cell + cell - 1, r * cell + cell - 1), fill=0)
    return img


def main() -> int:
    parser = argparse.ArgumentParser(description="Print a grid of random pixel invaders on the S01 printer.")
    parser.add_argument("--cols", type=int, default=4, help="Invaders across (default: 4).")
    parser.add_argument("--rows", type=int, default=6, help="Invaders down (default: 6).")
    parser.add_argument("--size", type=int, default=5, help="Cells per invader side (default: 5).")
    parser.add_argument("--seed", type=int, default=None, help="Seed for the swarm.")
    parser.add_argument("--out", type=Path, default=None)
    parser.add_argument("--darkness", type=int, choices=range(1, 6), default=3)
    parser.add_argument("--bottom-feed", type=int, default=24)
    parser.add_argument("--no-print", action="store_true")
    args = parser.parse_args()

    if not 2 <= args.cols <= 7 or not 1 <= args.rows <= 12 or not 4 <= args.size <= 9:
        parser.error("--cols 2-7, --rows 1-12, --size 4-9")
    seed = args.seed if args.seed is not None else random.randrange(1, 100000)
    rng = random.Random(seed)
    print(f"Spawning {args.cols * args.rows} invaders (seed {seed}) ...")

    card = Card()
    gap = 18
    iw = (card.inner_w - gap * (args.cols - 1)) // args.cols
    cell = iw // args.size
    sprite = cell * args.size
    grid_w = sprite * args.cols + gap * (args.cols - 1)
    grid_h = sprite * args.rows + gap * (args.rows - 1)
    canvas = Image.new("L", (grid_w, grid_h), 255)
    for r in range(args.rows):
        for c in range(args.cols):
            inv = draw_invader(rng, args.size, cell)
            canvas.paste(inv, (c * (sprite + gap), r * (sprite + gap)))

    card.title("INVADERS")
    card.line(f"{args.cols * args.rows} unique sprites", size=12, bold=False, center=True)
    card.gap(6).image(canvas, border=False)
    card.footer("procedural swarm", f"seed {seed}")
    out = args.out or ROOT / f"invaders_{seed}.png"
    return card.finish(out, args.bottom_feed, args.darkness, do_print=not args.no_print)


if __name__ == "__main__":
    raise SystemExit(main())