Initial data commit

Task/Xiaolin-Wus-line-algorithm/Scala/xiaolin-wus-line-algorithm-1.scala

@@ -0,0 +1,69 @@
+import java.awt.Color
+import math.{floor => ipart, round, abs}
+
+case class Point(x: Double, y: Double) {def swap = Point(y, x)}
+
+def plotter(bm: RgbBitmap, c: Color)(x: Double, y: Double, v: Double) = {
+  val X = round(x).toInt
+  val Y = round(y).toInt
+  val V = v.toFloat
+  // tint the existing pixels
+  val c1 = c.getRGBColorComponents(null)
+  val c2 = bm.getPixel(X, Y).getRGBColorComponents(null)
+  val c3 = (c1 zip c2).map{case (n, o) => n * V + o * (1 - V)}
+  bm.setPixel(X, Y, new Color(c3(0), c3(1), c3(2)))
+}
+
+def drawLine(plotter: (Double,Double,Double) => _)(p1: Point, p2: Point) {
+  def fpart(x: Double) = x - ipart(x)
+  def rfpart(x: Double) = 1 - fpart(x)
+  def avg(a: Float, b: Float) = (a + b) / 2
+
+  val steep = abs(p2.y - p1.y) > abs(p2.x - p1.x)
+  val (p3, p4) = if (steep) (p1.swap, p2.swap) else (p1, p2)
+  val (a, b) = if (p3.x > p4.x) (p4, p3) else (p3, p4)
+  val dx = b.x - a.x
+  val dy = b.y - a.y
+  val gradient = dy / dx
+  var intery = 0.0
+
+  def endpoint(xpxl: Double, yend: Double, xgap: Double) {
+    val ypxl = ipart(yend)
+    if (steep) {
+      plotter(ypxl,   xpxl, rfpart(yend) * xgap)
+      plotter(ypxl+1, xpxl,  fpart(yend) * xgap)
+    } else {
+      plotter(xpxl, ypxl  , rfpart(yend) * xgap)
+      plotter(xpxl, ypxl+1,  fpart(yend) * xgap)
+    }
+  }
+
+  // handle first endpoint
+  var xpxl1 = round(a.x);
+  {
+    val yend = a.y + gradient * (xpxl1 - a.x)
+    val xgap = rfpart(a.x + 0.5)
+    endpoint(xpxl1, yend, xgap)
+    intery = yend + gradient
+  }
+
+  // handle second endpoint
+  val xpxl2 = round(b.x);
+  {
+    val yend = b.y + gradient * (xpxl2 - b.x)
+    val xgap = fpart(b.x + 0.5)
+    endpoint(xpxl2, yend, xgap)
+  }
+
+  // main loop
+  for (x <- (xpxl1 + 1) to (xpxl2 - 1)) {
+    if (steep) {
+      plotter(ipart(intery)  , x, rfpart(intery))
+      plotter(ipart(intery)+1, x,  fpart(intery))
+    } else {
+      plotter(x, ipart (intery),  rfpart(intery))
+      plotter(x, ipart (intery)+1, fpart(intery))
+    }
+    intery = intery + gradient
+  }
+}

Task/Xiaolin-Wus-line-algorithm/Scala/xiaolin-wus-line-algorithm-2.scala

@@ -0,0 +1,10 @@
+val r = 120
+val img = new RgbBitmap(r*2+1, r*2+1)
+val line = drawLine(plotter(img, Color.GRAY)_)_
+img.fill(Color.WHITE)
+for (angle <- 0 to 360 by 30; θ = math toRadians angle; θ2 = θ + math.Pi) {
+  val a = Point(r + r * math.sin(θ), r + r * math.cos(θ))
+  val b = Point(r + r * math.sin(θ2), r + r * math.cos(θ2))
+  line(a, b)
+}
+javax.imageio.ImageIO.write(img.image, "png", new java.io.File("XiaolinWuLineAlgorithm.png"))