34 lines
897 B
Plaintext
34 lines
897 B
Plaintext
local canvas = require "canvas"
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local function trunc(x) return x >= 0 ? math.floor(x) : math.ceil(x) end
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local function circle(c, cx, cy, r, col)
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local d = trunc((5 - r * 4) / 4)
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local x = 0
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local y = r
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repeat
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c:set(cx + x, cy + y, col)
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c:set(cx + x, cy - y, col)
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c:set(cx - x, cy + y, col)
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c:set(cx - x, cy - y, col)
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c:set(cx + y, cy + x, col)
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c:set(cx + y, cy - x, col)
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c:set(cx - y, cy + x, col)
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c:set(cx - y, cy - x, col)
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if d < 0 then
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d += 2 * x + 1
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else
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d += 2 * (x - y) + 1
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y -= 1
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end
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++x
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until x > y
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end
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local c = canvas.new(400, 400)
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c:fill(0xffffff) -- white background
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-- Draw a blue circle with centre at (200, 200) and radius 100.
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circle(c, 200, 200, 100, 0xff0000)
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io.contents("mybmp.bmp", c:tobmp()) -- save to a bitmap file
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