Add Plasma effect; code cleanup.

Plasma.pde

@@ -0,0 +1,47 @@
+/**
+ * Plasma effect derived from http://lodev.org/cgtutor/plasma.html
+ *
+ * With such a low resolution of LEDs, some of the effect is lost. A 256x256 array looks much nicer.
+ */
+class Plasma extends Effect {
+
+  /**
+    * Steps: 1 - 100 (fast - slow)
+    * Saturation: 0 - 255
+    * Brightness: 0 - 255
+    * Zoom: 1 - 100 (low - high)
+    */
+  int _steps, _saturation, _brightness, _zoom;
+
+  Plasma(int _millis, int st, int sa, int br, int z) {
+    super(_millis);
+    colorMode(HSB);
+    if (st < 1 || st > 255) { st = 35; }
+    if (z < 1 || z > 100) { z = 8; }
+    _steps = st;
+    _saturation = sa % 256;
+    _brightness = br % 256;
+    _zoom = z;
+  }
+
+  void update() {
+    imageBuffer.beginDraw();
+    imageBuffer.loadPixels();
+    int x, y, hue;
+    color c;
+    for (int i = 0; i < imageBuffer.pixels.length; i++) {
+      x = i % width;
+      y = i / width;
+
+      hue = int(128.0 + (128.0 * sin(x / 16.0)) +
+                128.0 + (128.0 * sin(y / 32.0)) + 
+                128.0 + (128.0 * sin(sqrt(((x - width / 2.0) * (x - width / 2.0) + (y - height / 2.0) * (y - height / 2.0))) / 2.0)) +
+                128.0 + (128.0 * sin(sqrt((x * x + y * y)) / 2.0))) / _zoom;
+
+      c = color((hue + millis() / _steps) % 256, _saturation, _brightness);
+      imageBuffer.pixels[i] = c;
+    }
+    imageBuffer.updatePixels();
+    imageBuffer.endDraw();
+  }
+}