Added effect Matrix. Closes #7.

effects.h

@@ -296,3 +296,72 @@ class MultiDynamic : public SingleDynamic {
       for (int i=0; i<tile_count; i++) tiles[i] = CHSV(random8(), 120, 255);
     }
 };
+
+class MatrixColumn {
+  private:
+    int x, y;
+    int length;
+    Window* window;
+    int speed;
+    boolean running;
+    long last_move = 0;
+  public:
+    MatrixColumn() {}
+    MatrixColumn(Window* win, int xPos) {
+      window = win;
+      x = xPos;
+      running = false;
+    }
+
+    void start() {
+      y=-1;
+      length = random8()%16+4;
+      running = true;
+      speed = random8()/3 + 50;
+    }
+
+    void advance() {
+      y++;
+      if (y-length > window->h) running = false;
+    }
+
+    void draw() {
+      for(int i=0; i<length; i++) {
+        CRGB color;
+        if (i==0) color=CHSV(85, 0, 192);
+        else color=CHSV(85, 255, 255/(length-1)*(length-i));
+
+        setPixel(*window, x, y-i, color);
+      }
+    }
+
+    void loop() {
+      if (!running) {
+        if (random8() < 50) {
+          // Start the column again.
+          start();
+        }
+      } else {
+        if (millis() - last_move > speed) {
+          advance();
+          last_move = millis();
+        }
+
+        draw();
+      }
+    }
+};
+
+class MatrixEffect : public Effect {
+  private:
+    MatrixColumn columns[LED_WIDTH];
+  public:
+    boolean can_be_shown_with_clock() { return true; };
+    MatrixEffect() {
+      for (int i=0; i<LED_WIDTH; i++) columns[i]=MatrixColumn(&window, i);
+    }
+    void loop() {
+      clear(window);
+      for (int i=0; i<LED_WIDTH; i++) columns[i].loop();
+    }
+};