September 2017 Update

Task/Draw-a-sphere/Kotlin/draw-a-sphere.kotlin

@@ -0,0 +1,47 @@
+// version 1.0.6
+
+const val shades = ".:!*oe&#%@"
+val light  = doubleArrayOf(30.0, 30.0, -50.0)
+
+fun normalize(v: DoubleArray) {
+    val len = Math.sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2])
+    v[0] /= len; v[1] /= len; v[2] /= len
+}
+
+fun dot(x: DoubleArray, y: DoubleArray): Double {
+    val d = x[0] * y[0] + x[1] * y[1] + x[2] * y[2]
+    return if (d < 0.0) -d else 0.0
+}
+
+fun drawSphere(r: Double, k: Double, ambient: Double) {
+    val vec = DoubleArray(3)
+    var intensity: Int
+    var b : Double
+    var x: Double
+    var y: Double
+    for (i in Math.floor(-r).toInt() .. Math.ceil(r).toInt()) {
+        x = i + 0.5
+        for (j in Math.floor(-2.0 * r).toInt() .. Math.ceil(2.0 * r).toInt()) {
+            y = j / 2.0 + 0.5
+            if (x * x + y * y <= r * r) {
+                vec[0] = x
+                vec[1] = y
+                vec[2] = Math.sqrt(r * r - x * x - y * y)
+                normalize(vec)
+                b = Math.pow(dot(light, vec), k) + ambient
+                intensity = ((1.0 - b) * (shades.length - 1)).toInt()
+                if (intensity < 0) intensity = 0
+                if (intensity >= shades.length - 1) intensity = shades.length - 2
+                print(shades[intensity])
+            }
+            else print(' ')
+        }
+        println()
+    }
+}
+
+fun main(args: Array<String>) {
+    normalize(light)
+    drawSphere(20.0, 4.0, 0.1)
+    drawSphere(10.0, 2.0, 0.4)
+}