display actual fps in console

src/de/mp/jgame2d/core/GamePanel.java

@@ -46,16 +46,25 @@ public class GamePanel extends JPanel implements Runnable {
         double delta = 0;
         double lastTime = System.nanoTime();
         long currentTime;
+        long timer = 0;
+        int drawCount = 0;
 
         while(gameThread != null) {
             currentTime = System.nanoTime();
             delta += (currentTime - lastTime) / drawInterval;
+            timer += currentTime - lastTime;
             lastTime = currentTime;
 
             if(delta >= 1) {
                 update();
                 repaint();
                 delta--;
+                drawCount++;
+            }
+            if(timer >= 1000000000) {
+                System.out.println("FPS: " + drawCount);
+                drawCount = 0;
+                timer = 0;
             }
         }
     }