java - LWJGL 上下滚动

Question

所以我试图在 LWJGL 和 Slick2D 中创建一个滚动系统，按顺序上下滚动项目：

import java.util.ArrayList;

import org.newdawn.slick.AngelCodeFont;
import org.newdawn.slick.Color;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.Image;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.UnicodeFont;

/**
* @author michael_daley
*
* Class which allows any number of high score entries to be loaded with an avatar.
* This list is then scrolled up the screen
*/
public class HighScores {

   private int x;
   private int y;
   private float scrollSpeed;
   private UnicodeFont font;
   private ArrayList<HighScore> highScores;

   /**
    * Constructor
    * 
    * @param x
    * @param y
    * @param scrollSpeed Speed at which to scroll the high scores
    * @throws SlickException
    */
   public HighScores(int x, int y, float scrollSpeed) throws SlickException{
      this.x = x;
      this.y = y;
      this.scrollSpeed = scrollSpeed;

      /* Set up the font we are using */
       font = ScreenDashboardHome.font;

       highScores = new ArrayList<HighScore>();
   }

   /**
    * Add a high score entry to the HighScore object
    * 
    * @param score Text to be printed in the high score table
    * @param avatar Image to be displayed in the high score table
    * @param spacing Spacing to be applied between each high score entry
    */
   public void addScore(String score, Image avatar, int spacing) {
      HighScore hs = new HighScore(x, y+ (highScores.size() * spacing), scrollSpeed, font, score, avatar);
      highScores.add(hs);
   }

   /**
    * Update the individual high scores which will update their location
    * 
    * @param delta milliseconds since last update passed from the main Update method
    */
   public void update(int delta, boolean direction) {
      for (int i=0; i < highScores.size();i++) {
         HighScore hs = highScores.get(i);
         hs.Update(delta, direction);
      }
   }

   /**
    * Render the high scores to the graphics context
    * 
    * @param g Graphics context to which items should be rendered
    */
   public void render(Graphics g) {
      for (int i=0; i < highScores.size();i++) {
         HighScore hs = highScores.get(i);
         hs.Render(g);
      }      
   }

   /**
    * @author michael_daley
    * 
    * Inner Class which is used to store information on each high score and perform an
    * update on that high score which will change its location on the screen
    */
   public class HighScore {

      private String score;
      private Image avatar;
      private float x;
      private float y;
      private float speed;
      private UnicodeFont font;
      private Color c;
      private Color c2;

      public HighScore(float x, float y, float speed, UnicodeFont font2, String score, Image avatar) {
         this.font = font2;
         this.x = x;
         this.y = y;
         this.speed = speed;
         this.avatar = avatar;
         this.score = score;
         this.c = new Color(255, 255, 255, 1.0f);
      }

      /**
       * Update this highscore which will change its location and alpha
       * 
       * @param delta milliseconds since last update
       */
      public void Update(int delta, boolean direction) {
        if(direction == true){
          y -= speed;
          }else if(direction == false){
              y += speed;
          }
         if (y <= 300) {
            y = 1100;
         }
         if (y >= 1200) {            
          y = 299;           
          }
         System.out.println(y);
         /* Adjust the alpha of scores entering the screen */
         /* TODO: Come up with a better way to fade scores onto and off the screen */
         if (y > 800) {
            c = new Color (255, 255, 255, (600 - y) / 200);
         } else {
            c = new Color(255, 255, 255, 1.0f);
         }
         if (y > 800) {
             c2 = new Color(256,256,256,(600 - y) / 200).multiply(new Color(0,160,209));
          } else {
             c2 = new Color(0,160,209);
          }
      }

      /**
       * Render the highscore to the graphics context
       * 
       * @param g Graphics context to render too
       */
      public void Render(Graphics g) {
         g.setColor(c);
         g.drawRect(x, y, 500, 170); // tweet 1
         g.setColor(c2);
         g.fillRect(x + 1, y + 1, 499, 169);
         g.setColor(c);  
         g.drawRect(x + 1, y + 1, 82, 82); // tweet 1
         avatar.getScaledCopy(80, 80).draw(x + 2, y + 2, c);
         font.drawString((x + avatar.getWidth()) + 15, y, score, c);
         g.setColor(Color.white);
      }   
   }
}

但是它像这样堆叠它们： 任何人都可以解释我做错了什么，并为我提供一些更好的代码吗？