Java Game Dev：检查玩家是否介于两个y coords之间

Question

I'm making a game with Slick2D. When a player get's under a window with an enemy in it, they can shoot, and points will be added. I have every mechanic completed besides the shooting one. Here is my "plan" on how it'll work.

When the player gets below the window(which the program picks up on via y coordinate) and fires, points will be added to a counter.

How can I get my program to realize that the player is indeed below a window?

Thanks, and here's my PlayState code.

import org.newdawn.slick.GameContainer;
import org.newdawn.slick.Graphics;
import org.newdawn.slick.Input;
import org.newdawn.slick.state.BasicGameState;
import org.newdawn.slick.SlickException;
import org.newdawn.slick.state.StateBasedGame;
import org.newdawn.slick.Image;
import org.newdawn.slick.state.transition.FadeInTransition;
import org.newdawn.slick.state.transition.FadeOutTransition;
import java.util.Random;
import java.util.TimerTask;
import java.util.Timer;

public class PlayState extends BasicGameState{

int stateID = -1;

int w = SwegBoi.WIDTH;
int h = SwegBoi.HEIGHT;
static int enemylocation;
float s = SwegBoi.SCALE;
Image playbackground;
Image swegboiplayer;
Image quit;
Image enemy1;
Image enemy2;
float playery;
int score = 0;

final static Random ran = new Random();
static Timer tm = new Timer();
static long startTime = System.currentTimeMillis();

public static void main(String args){

}


public PlayState(int stateID){
    this.stateID = stateID;
}

@Override
public void init(GameContainer gc, StateBasedGame sbg)
        throws SlickException {
    swegboiplayer = new Image("resources/swegboibackgun.png");
    playbackground = new Image("resources/playstatebackground.png");
    quit = new Image("resources/mainmenuquit.png");
    enemy1 = new Image("resources/enemy1.png");
    enemy2 = new Image("resources/enemy1.png");

    tm.schedule(new TimerTask() {

        @Override
        public void run() {
            enemylocation = ran.nextInt(4) + 1;
        }
    }, 1, 2000);


}




@Override
public void render(GameContainer gc, StateBasedGame sbg, Graphics g)
        throws SlickException {
    playbackground.setFilter(Image.FILTER_NEAREST);
    playbackground.draw(0, 0, s*10);
    quit.draw((w-175*s),5 *s,s/2);

    if(enemylocation==1){
        enemy1.setFilter(Image.FILTER_NEAREST);
        enemy1.draw(200,170,s*10);
    }
    if(enemylocation==2){
        enemy1.setFilter(Image.FILTER_NEAREST);
        enemy1.draw(200,360,s*10);  
    }
    if(enemylocation==3){
        enemy1.setFilter(Image.FILTER_NEAREST);
        enemy1.draw(950,170,s*10);
    }
    if(enemylocation==4){
        enemy1.setFilter(Image.FILTER_NEAREST);
        enemy1.draw(950,360,s*10);
    }

    swegboiplayer.setFilter(Image.FILTER_NEAREST);
    swegboiplayer.draw((w*s)/2-(playery*s), 450*s, s*5);

    g.drawString("Alpha V0.1",6,6);
}



@Override
public void update(GameContainer gc, StateBasedGame sbg, int delta)
        throws SlickException {
    Input input = gc.getInput();
    if(input.isKeyDown(Input.KEY_LEFT)){playery += 17;}
    if(input.isKeyDown(Input.KEY_RIGHT)){playery -= 17;}
    int mouseX = input.getMouseX();
    int mouseY = input.getMouseY();

    if(mouseHover(mouseX,mouseY,(w-175*s),5*s,quit.getHeight()/2,quit.getWidth()) == true){
        if(input.isMousePressed(0)){
            sbg.enterState(SwegBoi.MAINMENUSTATE,new FadeOutTransition(), new FadeInTransition());
        }
        quit = new Image("resources/mainmenuquithover.png");
    }else{
        quit = new Image("resources/mainmenuquit.png");

    }}



@Override
public int getID() {
    return stateID;
}


public boolean mouseHover(int mouseX, int mouseY, float x, float y, float height, float width){
    if((mouseX >= x && mouseX <= x + width && mouseY >= y && mouseY <= y + height)){
        return true;
    }else{
        return false;
    }

}}

Answer 1

Something like this should work. Every time you move, check if you are in a range of an enemy x position and determine if shooting should be enabled or disabled. Define some kind of range for each enemies X position.

   private void checkShootStatus()
   {
      // Calculate image bounds X Position + width
      float swegboiplayerEndBound = swegboiplayer.getX() + swegboiplayer.getWidth();
      float enemyEndBound = enemy.getX() + enemy.getWidth();

      // Check enemy 1
      if (swegboiplayerEndBound > enemy.getX() && swegboiplayer.getX() < enemyEndBound)
      {
         canShoot = true;
      }
      else
      {
         canShoot = false;
      }
   }

Since you cannot get the x location of an image, create a wrapper class to track the x/y positions of the player and enemy.

public class Player extends Image
{
   private String image;
   private float x = 0;
   private float y = 0;

   public Player(String image) throws SlickException
   {
      super(image);

      this.setImage(image);
   }

   public float getY()
   {
      return y;
   }

   public void setY(float y)
   {
      this.y = y;
   }

   public String getImage()
   {
      return image;
   }

   public void setImage(String image)
   {
      this.image = image;
   }

   public float getX()
   {
      return x;
   }

   public void setX(float x)
   {
      this.x = x;
   }
}

Enemy

public class Enemy extends Image
{
   private String image;
   private int x;
   private int y;

   public Enemy(String image) throws SlickException
   {
      super(image);

      this.setImage(image);
   }

   public int getY()
   {
      return y;
   }

   public void setY(int y)
   {
      this.y = y;
   }

   public String getImage()
   {
      return image;
   }

   public void setImage(String image)
   {
      this.image = image;
   }

   public int getX()
   {
      return x;
   }

   public void setX(int x)
   {
      this.x = x;
   }
}