Data update

Task/Bitmap-Midpoint-circle-algorithm/Pluto/bitmap-midpoint-circle-algorithm.pluto

@@ -0,0 +1,33 @@
+local canvas = require "canvas"
+
+local function trunc(x) return x >= 0 ? math.floor(x) : math.ceil(x) end
+
+local function circle(c, cx, cy, r, col)
+    local d = trunc((5 - r * 4) / 4)
+    local x = 0
+    local y = r
+    repeat
+        c:set(cx + x, cy + y, col)
+        c:set(cx + x, cy - y, col)
+        c:set(cx - x, cy + y, col)
+        c:set(cx - x, cy - y, col)
+        c:set(cx + y, cy + x, col)
+        c:set(cx + y, cy - x, col)
+        c:set(cx - y, cy + x, col)
+        c:set(cx - y, cy - x, col)
+        if d < 0 then
+            d += 2 * x + 1
+        else
+            d += 2 * (x - y) + 1
+            y -= 1
+        end
+        ++x
+    until x > y
+end
+
+local c = canvas.new(400, 400)
+c:fill(0xffffff)  -- white background
+
+-- Draw a blue circle with centre at (200, 200) and radius 100.
+circle(c, 200, 200, 100, 0xff0000)
+io.contents("mybmp.bmp", c:tobmp()) -- save to a bitmap file