Slick2d如何检查一个形状是否包含任何对象？ Java的

Question

i'm new to Slick2d and to this page too, i tried asking the slick forums, but there aren't many people so i couldn't get an answer

Anyway, i've been trying to create a platformer engine in Slick2d java game library, and i was thinking of using the contains and intersects methods of the Shape class.

The thing is, if I want to check if a shape contains any object of any kind (or any object from a specific class), Is there a way to do that? all tutorials i've found explain how to test collision with one single shape, but what if i want to check for any object?

package juegoconslick;

import java.util.ArrayList;
import org.newdawn.slick.*;
import org.newdawn.slick.geom.Rectangle;
import org.newdawn.slick.geom.Shape;
public class JuegoConSlick extends BasicGame {

Jugador player;
Input entrada;
 Shape hitbox;
bloque bloq;
ArrayList<bloque> bloques = new ArrayList<>();
public JuegoConSlick(){

    super("Mi prueba");

}

public static void main(String[] args) {

    AppGameContainer juegito;
    try{
     juegito = new AppGameContainer(new JuegoConSlick());
     juegito.setDisplayMode(630,400,false);
     juegito.setMaximumLogicUpdateInterval(60);
     juegito.setMaximumLogicUpdateInterval(50);
     juegito.setAlwaysRender(true);
     juegito.setVSync(true);
     juegito.start();

    }catch(Exception ex){
        System.exit(0);
    }
}

@Override
public void init(GameContainer gc) throws SlickException {

     player = new Jugador();
     hitbox = new Rectangle(player.X, player.Y, 10, 10);
     bloq = new bloque(50,50,50,50);



}

@Override
public void update(GameContainer gc, int i) throws SlickException {
   intersecta();
    Input entrad = gc.getInput();
   if(entrad.isKeyDown(Input.KEY_RIGHT) && player.X<600){
       player.X+=3;
       player.sprite.update(1);
       hitbox.setX(player.X);
   }
   if(entrad.isKeyDown(Input.KEY_LEFT) && player.X>0){
       player.X-=3;
       player.sprite.update(1);
       hitbox.setX(player.X);
   }
   if(entrad.isKeyDown(Input.KEY_UP) && player.Y>0){
       player.Y-=3;
       player.sprite.update(1);
       hitbox.setY(player.Y);
   }
   if(entrad.isKeyDown(Input.KEY_DOWN) && player.Y<370){
       player.Y+=3;
       player.sprite.update(1);
       hitbox.setY(player.Y);
   }
}

@Override
public void render(GameContainer gc, Graphics grphcs) throws SlickException {
    grphcs.draw(bloq.bloque);
    grphcs.draw(hitbox);

    }

public void intersecta(){
    try{
if(hitbox.contains(null)){//i tried checking if it didnt contain any object,           

}else{
     System.exit(0);

}

    }catch(Exception ex){

    }



}

}

EDIT: i think i have found a solution, though im not sure if its the most efficient.

basiaclly, i'll save all objects of the same class in an ArrayList:

ArrayList<bloque> bloques = new ArrayList<>();
 bloques.add(new bloque(50,50,100,100));
     bloques.add(new bloque(100,100,100,100));

Then, what im going to do is check the entire arraylist each time i call the intersects method:

  public boolean intersecta(){
    boolean devuelve=false;
   for(int i=0; i<bloques.size(); i++){          
       if(hitbox.intersects(bloques.get(i).bloque)){

           devuelve=true;
       }

   }

    return devuelve;

}

then im going to use the value i get from intersects to decide whether the player can move or not

 public void update(GameContainer gc, int i) throws SlickException {

    Input entrad = gc.getInput();
   if(entrad.isKeyDown(Input.KEY_RIGHT) && player.X<600 && intersecta()==false){

       player.X+=3;
       player.sprite.update(1);
       hitbox.setX(player.X);
   }

and so on with the other keys.... so im not sure if its the best solution, but as far as i have seen it seems to be working. I hope this results useful for others.

Answer 1

I recommend to create a new Class. This class Needs to inherit an Slick2d Shape, so for instance:

public class ShapeWithReference extends Rectangle{}

This class can have a list or a single object reference:

public class ShapeWithReference Rectangle{
Object reference = new String("hello"); //This is dirty and can be replaced by any object.
}

Since your new class is a Slick2D shape you can now find out whether it is contained by another shape:

Rectangle rec = new Rectangle();
if(rec.contains(ShapeWithReference)){
   if(ShapeWithReference.reference instanceof String){
       System.out.println((String)ShapeWithReference.reference);
   }
}

Contains checks whether the shape really contains another shape. So they are not just intersecting. So that's the first part you check, the second one is whether the reference Attribute of the Shape is for eg a String. So if our first rectangle contains our new class and the reference of this class is type of a String this String is supposed to be written in to the console.

Hope this helps or gives you a hint.

---

EDIT:

public class SlickGame extends BasicGame {

static AppGameContainer appgc;
Rectangle rec;
ShapeWithReference swr;

public SlickGame(String title) {
    super(title);
}

@Override
public void render(GameContainer container, Graphics g) throws SlickException {

}

@Override
public void init(GameContainer container) throws SlickException {
    rec = new Rectangle(0, 0, 64, 64);
    swr = new ShapeWithReference(0, 0, 1, 1);
}

@Override
public void update(GameContainer container, int delta) throws SlickException {
    if(rec.intersects(swr)){
       if(swr.reference instanceof String){
           System.out.println((String)swr.reference);
       }
       else if(swr.reference instanceof Integer){
           System.out.println((Integer)swr.reference);
       }
       else if(swr.reference instanceof Shape){
           Shape temp = (Shape)swr.reference;
           System.out.println(temp.getWidth());
       }
    }
}

public static void main(String[] args) {
    try {

        appgc = new AppGameContainer(new SlickGame("title"));
        appgc.setDisplayMode(800, 600, false);
        appgc.setTargetFrameRate(60);
        appgc.setFullscreen(false);
        appgc.start();

    } catch (SlickException ex) {
        ex.printStackTrace();
    }
}

}

This is the code you should be able to copy & paste directly. It does work for me, I'm not sure if I got your problem right but after the instanceof Operator you can just add the Class Name and check for it, I added some examples with an Integer and a Shape.

This is the 2nd class:

public class ShapeWithReference extends Rectangle {

private static final long serialVersionUID = 1L;

public ShapeWithReference(float x, float y, float width, float height) {
    super(x, y, width, height);
}

Object reference = new String("hello");

}

Does this work for you?