60 lines
2.1 KiB
Python
60 lines
2.1 KiB
Python
#!/usr/bin/env python3
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"""Turn a generated decal (a picture on a flat magenta background) into a transparent tile for
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the high-res atlas: magenta keyed out, scaled down without magenta fringes (premultiplied), the
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alpha made hard (pixels are either there or not, like the rest of the pixel art).
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Usage:
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make_decal.py raw.png out_prefix --size 128 [--gray]
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--gray neutral grey (a dark crack whose lines took on the magenta of the background)
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Writes out_prefix-<size>.png and out_prefix-<size>-preview.png (on a grey floor, scaled up 3x).
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Needs Pillow.
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"""
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import argparse
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from PIL import Image
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def main():
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ap = argparse.ArgumentParser()
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ap.add_argument("raw")
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ap.add_argument("out")
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ap.add_argument("--size", type=int, default=128)
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ap.add_argument("--gray", action="store_true")
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a = ap.parse_args()
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img = Image.open(a.raw).convert("RGBA")
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px = img.load()
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for y in range(img.height):
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for x in range(img.width):
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r, g, b, _ = px[x, y]
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if r > g + 40 and b > g + 40:
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px[x, y] = (0, 0, 0, 0)
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# premultiplied scaling: transparent pixels add nothing to the colour
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small = img.resize((a.size, a.size), Image.BOX)
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sp = small.load()
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for y in range(a.size):
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for x in range(a.size):
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r, g, b, al = sp[x, y]
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if al < 110:
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sp[x, y] = (0, 0, 0, 0)
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else:
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k = 255 / al
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c = (min(255, int(r * k)), min(255, int(g * k)), min(255, int(b * k)))
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if a.gray:
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v = min(c) * 0.9
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c = (int(v), int(v), int(v * 1.05))
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sp[x, y] = c + (255,)
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# Pillow's BOX filter works on straight alpha; transparent pixels were black, so colours near
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# the edges come out darker, which suits the dark outlines
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small.save(f"{a.out}-{a.size}.png")
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prev = Image.new("RGBA", (a.size, a.size), (90, 86, 84, 255))
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prev.alpha_composite(small)
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prev.resize((a.size * 3, a.size * 3), Image.NEAREST).save(f"{a.out}-{a.size}-preview.png")
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print(f"{a.out}-{a.size}.png")
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if __name__ == "__main__":
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main()
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