Data commit

Task/Draw-a-sphere/Sidef/draw-a-sphere.sidef

@@ -0,0 +1,33 @@
+func normalize (vec)  { vec »/» (vec »*« vec -> sum.sqrt) }
+func dot       (x, y) { -(x »*« y -> sum) `max` 0 }
+ 
+var x = var y = 255
+x += 1 if x.is_even    # must be odd
+ 
+var light = normalize([ 3, 2, -5 ])
+var depth = 255
+ 
+func draw_sphere(rad, k, ambient) {
+    var pixels = []
+    var r2 = (rad * rad)
+    var range = (-rad .. rad)
+    for x,y in (range ~X range) {
+        if ((var x2 = x*x) + (var y2 = y*y) < r2) {
+            var vector = normalize([x, y, (r2 - x2 - y2).sqrt])
+            var intensity = (dot(light, vector)**k + ambient)
+            var pixel = (0 `max` (intensity*depth -> int) `min` depth)
+            pixels << pixel
+        }
+        else {
+            pixels << 0
+        }
+    }
+    return pixels
+}
+ 
+var outfile = %f'sphere-sidef.pgm'
+var out = outfile.open('>:raw')
+ 
+out.say("P5\n#{x} #{y}\n#{depth}")    # .pgm header
+out.print(draw_sphere((x-1)/2, .9, .2).map{.chr}.join)
+out.close