splatter-tennis/assets/_fine.py

# _fine.py — turn a generated sheet into FULL-RESOLUTION sprites.
#
# _slice.py resamples with NEAREST, which is right when the generator's art-pixel grid is coarse but
# shreds fine detail at a non-integer ratio. This one instead:
#   1. detects the art-pixel BLOCK SIZE the generator actually drew at, and snaps to that grid
#      (one output pixel per art pixel — no half-blocks, no broken outlines),
#   2. common-scales the sheet to the target height with a box filter,
#   3. quantises every pixel back to the sheet's own palette, so the result is flat pixel art
#      rather than a blurred photo of pixel art.
# Usage: _fine.py sheet.png out1.png out2.png ...   [--h 224] [--cut X,Y,...]
import sys
from PIL import Image
import numpy as np

TARGET_H = 224
KEY_D2 = 60 * 60
MIN_GAP = 12
MIN_BLOB = 60

def key(im, defringe=2):
    a = np.array(im.convert('RGBA'))
    bg = a[0, 0, :3].astype(int)
    d = ((a[..., :3].astype(int) - bg) ** 2).sum(2)
    magenta = np.minimum(a[..., 0], a[..., 2]).astype(int) > a[..., 1].astype(int) + 40
    a[(d < KEY_D2) | magenta] = 0
    # De-fringe. The generator does not always give you a pure key colour, and whatever it does give
    # bleeds a halo one pixel into the sprite — which survives as a magenta rim once the sprite is on
    # a green court. Anything on the EDGE that is still leaning towards the background goes too.
    # ...but each pass also eats a 1-pixel line, and a racket frame IS a 1-pixel line: two passes
    # removed the rackets from a whole serve sheet and left men holding a grip. --defringe 1 (or 0)
    # is for sheets whose art is that thin.
    for _ in range(defringe):
        solid = a[..., 3] > 0
        edge = solid & ~(np.roll(solid, 1, 0) & np.roll(solid, -1, 0) & np.roll(solid, 1, 1) & np.roll(solid, -1, 1))
        near = ((a[..., :3].astype(int) - bg) ** 2).sum(2) < KEY_D2 * 9
        a[edge & near] = 0
    return a

def block_size(a):
    ink = a[..., 3] > 0
    ys, xs = np.where(ink)
    sub = a[ys.min():ys.max()+1, xs.min():xs.max()+1]
    h, w = sub.shape[:2]
    best = 1
    for b in range(2, 13):
        if h < b * 6: break
        ok = tot = 0
        for y in range(0, h - b, b):
            for x in range(0, w - b, b):
                blk = sub[y:y+b, x:x+b].reshape(-1, 4)
                tot += 1
                if (blk == blk[0]).all(): ok += 1
        if tot and ok / tot > 0.82: best = b
    return best

def frames(a, cuts):
    ink = (a[..., 3] > 0)
    cols = ink.any(0)
    out, start, gap = [], None, 0
    for x in range(len(cols)):
        if cols[x]:
            if start is None: start = x
            gap = 0
        elif start is not None:
            gap += 1
            if gap >= MIN_GAP: out.append((start, x - gap + 1)); start = None
    if start is not None: out.append((start, len(cols)))
    for c in sorted(cuts, reverse=True):          # manual splits where two figures touch
        for i, (x0, x1) in enumerate(out):
            if x0 < c < x1: out[i:i+1] = [(x0, c), (c, x1)]; break
    return out

def main(sheet, outs, target_h, cuts, anchor, defringe=2):
    a = key(Image.open(sheet), defringe)
    b = block_size(a)
    crops = []
    for x0, x1 in frames(a, cuts):
        sub = a[:, x0:x1]
        ys = np.where((sub[..., 3] > 0).any(1))[0]; xs = np.where((sub[..., 3] > 0).any(0))[0]
        crops.append(sub[ys.min():ys.max()+1, xs.min():xs.max()+1])
    if len(crops) != len(outs):
        sys.exit(f'ERROR: found {len(crops)} frames, expected {len(outs)} ({sheet})')
    # palette = the colours the generator actually used, on the largest frame
    big = max(crops, key=lambda c: (c[..., 3] > 0).sum())
    px = big[big[..., 3] > 200][:, :3]
    pal = np.unique((px // 8) * 8, axis=0)
    # ONE scale for the sheet, anchored on a chosen frame — the STANDING pose is the 224 reference,
    # so a smash with the arm overhead stays legitimately taller (the game scales off img.height).
    anchor_h = crops[anchor].shape[0] if 0 <= anchor < len(crops) else max(c.shape[0] for c in crops)
    k = target_h / (anchor_h / b)
    for c, out in zip(crops, outs):
        h, w = c.shape[:2]
        snap = Image.fromarray(c, 'RGBA').resize((max(1, round(w / b)), max(1, round(h / b))), Image.BOX)
        fh = max(1, round(snap.height * k)); fw = max(1, round(snap.width * k))
        im = snap.resize((fw, fh), Image.BOX)
        arr = np.array(im).astype(int)
        solid = arr[..., 3] > 110
        flat = arr[..., :3].reshape(-1, 3)
        idx = ((flat[:, None, :] - pal[None, :, :]) ** 2).sum(2).argmin(1)
        arr[..., :3] = pal[idx].reshape(arr.shape[0], arr.shape[1], 3)
        arr[..., 3] = np.where(solid, 255, 0)
        Image.fromarray(arr.astype('uint8'), 'RGBA').save(out)
        print(f'{out}: {fw}x{fh}  (art block {b} in source)')

if __name__ == '__main__':
    args = sys.argv[1:]
    th, cuts, anchor = TARGET_H, [], -1
    if '--h' in args: i = args.index('--h'); th = int(args[i+1]); del args[i:i+2]
    if '--cut' in args: i = args.index('--cut'); cuts = [int(v) for v in args[i+1].split(',')]; del args[i:i+2]
    de = 2
    if '--defringe' in args: i = args.index('--defringe'); de = int(args[i+1]); del args[i:i+2]
    if '--anchor' in args: i = args.index('--anchor'); anchor = int(args[i+1]); del args[i:i+2]
    main(args[0], args[1:], th, cuts, anchor, de)