June 2018 Update

Task/Draw-a-sphere/MATLAB/draw-a-sphere.m

@@ -0,0 +1 @@
+figure; sphere

Task/Draw-a-sphere/REXX/draw-a-sphere.rexx

@@ -20,7 +20,6 @@ drawSphere: procedure;  parse arg r, k, ambient              /*get the arguments
                               parse value  norm(x  y  sqrt(rr-xx-yy) )   with   v1  v2  v3
                               dot=s1*v1  +  s2*v2  +  s3*v3  /*the dot product of the Vs*/
                               if dot>0  then dot=0           /*if positive, make it zero*/     /*◄■■■■ same as:  dot=max(0, dot) */
-                              if dot>0  then dot=0           /*if positive, make it zero*/
                               b=-dot**k  +  ambient          /*calculate the brightness.*/
                               if b<=0   then brite=shadeLen
                                         else brite=max( (1-b) * shadeLen,  0)  % 1

Task/Draw-a-sphere/Scala/draw-a-sphere.scala

@@ -0,0 +1,34 @@
+object Sphere extends App {
+  private val (shades, light) = (Seq('.', ':', '!', '*', 'o', 'e', '&', '#', '%', '@'), Array(30d, 30d, -50d))
+
+  private def drawSphere(r: Double, k: Double, ambient: Double): Unit = {
+    def dot(x: Array[Double], y: Array[Double]) = {
+      val d = x.head * y.head + x(1) * y(1) + x.last * y.last
+      if (d < 0) -d else 0D
+    }
+
+    for (i <- math.floor(-r).toInt to math.ceil(r).toInt; x = i + .5)
+      println(
+        (for (j <- math.floor(-2 * r).toInt to math.ceil(2 * r).toInt; y = j / 2.0 + .5)
+          yield if (x * x + y * y <= r * r) {
+
+            def intensity(vec: Array[Double]) = {
+              val b = math.pow(dot(light, vec), k) + ambient
+              if (b <= 0) shades.length - 2
+              else math.max((1 - b) * (shades.length - 1), 0).toInt
+            }
+
+            shades(intensity(normalize(Array(x, y, scala.math.sqrt(r * r - x * x - y * y)))))
+          } else ' ').mkString)
+  }
+
+  private def normalize(v: Array[Double]): Array[Double] = {
+    val len = math.sqrt(v.head * v.head + v(1) * v(1) + v.last * v.last)
+    v.map(_ / len)
+  }
+
+  normalize(light).copyToArray(light)
+  drawSphere(20, 4, .1)
+  drawSphere(10, 2, .4)
+
+}