Data commit

Task/Draw-a-sphere/Lua/draw-a-sphere.lua

@@ -0,0 +1,37 @@
+require ("math")
+
+shades = {'.', ':', '!', '*', 'o', 'e', '&', '#', '%', '@'}
+
+function normalize (vec)
+    len = math.sqrt(vec[1]^2 + vec[2]^2 + vec[3]^2)
+    return {vec[1]/len, vec[2]/len, vec[3]/len}
+end
+
+light = normalize{30, 30, -50}
+
+function dot (vec1, vec2)
+    d = vec1[1]*vec2[1] + vec1[2]*vec2[2] + vec1[3]*vec2[3]
+    return d < 0 and -d or 0
+end
+
+function draw_sphere (radius, k, ambient)
+    for i = math.floor(-radius),-math.floor(-radius) do
+        x = i + .5
+        local line = ''
+        for j = math.floor(-2*radius),-math.floor(-2*radius) do
+            y = j / 2 + .5
+            if x^2 + y^2 <= radius^2 then
+                vec = normalize{x, y, math.sqrt(radius^2 - x^2 - y^2)}
+                b = dot(light,vec) ^ k + ambient
+                intensity = math.floor ((1 - b) * #shades)
+                line = line .. (shades[intensity] or shades[1])
+            else
+                line = line .. ' '
+            end
+        end
+        print (line)
+    end
+end
+
+draw_sphere (20, 4, 0.1)
+draw_sphere (10, 2, 0.4)