停止玩家卡在一定的座標？

Question

對，過去幾天我一直在學習Slick2D，並想知道爲什麼以及如何解決我的玩家卡在碰撞座標if語句中。

這是我的主播放狀態代碼，Update void的第一對幾行是if條件以查看角色（窗口的中間部分）是否在內部以協調......如果玩家隨後移動了em基本回來。

package com.ohdanbo.game; 

import org.newdawn.slick.*; 
import org.newdawn.slick.geom.Rectangle; 
import org.newdawn.slick.geom.Shape; 
import org.newdawn.slick.state.*; 

public class Play extends BasicGameState { 

    Animation dude, movingUp, movingDown, movingLeft, movingRight; 
    Image map; 
    boolean quit = false; 
    int[] duration = { 200, 200 }; 
    float dudePositionX = 0; 
    float dudePositionY = 0; 
    float shiftX = (640/2) - (40/2); 
    float shiftY = (360/2) - (40/2); 
    Image pauseBG; 
    Shape rectangle; 
    float rectX = 0; 
    float rectY = 0; 

    public Play(int state) { 
    } 

    public void init(GameContainer gc, StateBasedGame sbg) throws SlickException { 
     //rectangle = new Rectangle(100,100); 
     pauseBG = new Image("res/bg.png"); 
     map = new Image("res/worldTemp.png"); 
     Image[] walkUp = { new Image("res/charBack.png"), new Image("res/charBack.png") }; 
     Image[] walkDown = { new Image("res/charFront.png"), new Image("res/charFront.png") }; 
     Image[] walkLeft = { new Image("res/charLeft.png"), new Image("res/charLeft.png") }; 
     Image[] walkRight = { new Image("res/charRight.png"), new Image("res/charRight.png") }; 

     movingUp = new Animation(walkUp, duration, false); 
     movingDown = new Animation(walkDown, duration, false); 
     movingLeft = new Animation(walkLeft, duration, false); 
     movingRight = new Animation(walkRight, duration, false); 
     dude = movingDown; 
    } 

    public void render(GameContainer gc, StateBasedGame sbg, Graphics g) throws SlickException { 
     map.draw(dudePositionX, dudePositionY); 
     dude.draw(shiftX, shiftY); 
     //g.draw(rectangle); 
     // g.setColor(Color.black); 
     g.drawString("Dude's X: " + dudePositionX + "\nDude's Y: " + dudePositionY, 400, 20); 

     if (quit == true) { 
      pauseBG.draw(0, 0); 
      g.drawString("Continue (C)", 250, 100); 
      g.drawString("Main Menu (M)", 250, 150); 
      g.drawString("Quit (Q)", 250, 200); 
      if (quit == false) { 
       g.clear(); 
      } 
     } 
    } 

    public void update(GameContainer gc, StateBasedGame sbg, int delta) throws SlickException { 
     Input input = gc.getInput(); 

     if ((dudePositionX > 100) && (dudePositionX < 267) && (dudePositionY > -68) && (dudePositionY < 156)) { 
      if(input.isKeyDown(Input.KEY_UP)){dudePositionY -= delta * .1f;} 
      if(input.isKeyDown(Input.KEY_DOWN)){dudePositionY += delta * .1f;} 
      if(input.isKeyDown(Input.KEY_LEFT)){dudePositionX -= delta * .1f;} 
      if(input.isKeyDown(Input.KEY_RIGHT)){dudePositionX += delta * .1f;} 
     } 

     if (input.isKeyDown(Input.KEY_UP)) { 
      dude = movingUp; 
      dudePositionY += delta * .1f; // increase the Y coordinates of bucky 
              // (move him up) 
      if (dudePositionY > 162) { 
       dudePositionY -= delta * .1f; // dont let him keep going up if 
               // he reaches the top 
      } 
     } 
     if (input.isKeyDown(Input.KEY_DOWN)) { 
      dude = movingDown; 
      dudePositionY -= delta * .1f; 
      if (dudePositionY < -600) { 
       dudePositionY += delta * .1f; 
      } 
     } 
     if (input.isKeyDown(Input.KEY_LEFT)) { 
      dude = movingLeft; 
      dudePositionX += delta * .1f; 
      if (dudePositionX > 324) { 
       dudePositionX -= delta * .1f; 
      } 
     } 
     if (input.isKeyDown(Input.KEY_RIGHT)) { 
      dude = movingRight; 
      dudePositionX -= delta * .1f; 
      if (dudePositionX < -840) { 
       dudePositionX += delta * .1f; 
      } 
     } 

     if (input.isKeyDown(Input.KEY_ESCAPE)) { 
      quit = true; 
     } 

     if (quit == true) { 
      if (input.isKeyDown(Input.KEY_C)) { 
       quit = false; 
      } 
      if (input.isKeyDown(Input.KEY_M)) { 
       sbg.enterState(0); 
       quit = false; 
      } 
      if (input.isKeyDown(Input.KEY_Q)) { 
       System.exit(0); 
      } 
     } 
    } 

    public int getID() { 
     return 1; 
    } 

} 

Answer 1

想要如何處理碰撞檢測/碰撞響應這樣的問題是爲了理解衝突在遊戲循環中應如何發揮。

基本上，這一切都基於操作才能得到正確的結果：

• 以人物初始位置考慮進去，並保存它。
• 從玩家輪詢控制器輸入，並更新玩家座標。
• 如果玩家是「越界」或與任何碰撞你不想它，它恢復到原來的位置（例如，你在步驟1中保存的初始位置）

嘗試的方法像這樣，而不是直接集成到您的控制器代碼，因爲我在下面的代碼片段中指出：

if (input.isKeyDown(Input.KEY_RIGHT)) { 
     dude = movingRight; 
     dudePositionX -= delta * .1f; 

     // Do these lines LATER after all the 
     // controls of movement have been seen and the player updated 
     if (dudePositionX < -840) { 
      dudePositionX += delta * .1f; 
      // Instead of this line, you would have it be something like: 
      // dudePositionX = previousDudePositionX; 
     } 
    }