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Thread: Drawing Objects on Screen

  1. #1
    Member Gravity Games's Avatar
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    Default Drawing Multiple Objects on Screen at once

    For some reason, I'm having a hard time drawing objects on screen. Here's my code:

    Level.java
    package com.gravitygamesinteractive.kylethecaiman;
     
    import java.awt.*;
    import java.util.*;
    import java.io.File;
     
    public class Level {
    	public Tile tile;
    	private Scanner s;
    	private int objectId;
    	private int spx;
    	private int spy;
    	private String oidstr;
    	private String xstr;
    	private String ystr;
    	private ArrayList<String> objarray= new ArrayList<String>();
    	private ArrayList<String> xarray= new ArrayList<String>();
    	private ArrayList<String> yarray= new ArrayList<String>();
    	public Level(){
    		setStage();
    	}
     
    	public void tick(){
     
    	}
     
    	public void render(Graphics g){
    	}
     
    	public void setStage(){
    		tile=new Tile(0,0);
    		tile=new Tile(0,0);
    		}
    	}
    }

    Tile.java:
    package com.gravitygamesinteractive.kylethecaiman;
     
    import java.awt.*;
     
    import javax.swing.JFrame;
     
    public class Tile extends Rectangle{
    	private static final long serialVersionUID=1L;
    	public Tile(int x, int y){
    		this.x=x;
    		this.y=y;
    	}
    	public void render(Graphics g){
    		g.setColor(Color.red);
    		g.drawRect(x,y,16,16);
    	}
    }

    The problem is that the Tile object will only be created at the last instance of "tile=new Tile". I can't seem to figure out how to create them both. Just writing new Tile doesn't work either, as the objects won't draw.
    Last edited by Gravity Games; August 27th, 2012 at 11:36 AM. Reason: I changed the title to be more descriptive
    Current Projects (and planned release dates):

    Chomp's Wacky Worlds [???] (PC, Android and Ouya)
    Kyle the Caiman [???] (PC, Android and Ouya)
    KTC: King Crocko's Mystic Maze [???] (PC, Android and Ouya)


  2. #2
    Member Gravity Games's Avatar
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    Default Re: Drawing Objects on Screen

    I figured out I need an arraylist to create more than one of the same object. Unfortunately, I can't figure out how to call the render method on each individual object. Here's what I'm got:

    Level.java:
    package com.gravitygamesinteractive.kylethecaiman;
     
    import java.awt.*;
    import java.util.*;
    import java.io.File;
     
    public class Level {
    	public ArrayList<Tile> tile=new ArrayList<Tile>();
    	private Scanner s;
    	private int objectId;
    	private int spx;
    	private int spy;
    	private String oidstr;
    	private String xstr;
    	private String ystr;
    	private ArrayList<String> objarray= new ArrayList<String>();
    	private ArrayList<String> xarray= new ArrayList<String>();
    	private ArrayList<String> yarray= new ArrayList<String>();
    	public Level(){
            setStage();
    	}
     
    	public void tick(){
     
    	}
     
    	public void render(Graphics g){
    		for(int d=0;d<tile.size();d++){
    			tile<Tile>.render(g);
    		}
    	}
    	public void setStage(){
    		tile.add(new Tile(0,0));
    		tile.add(new Tile(0,0));
                    }
    	}
    }
    Current Projects (and planned release dates):

    Chomp's Wacky Worlds [???] (PC, Android and Ouya)
    Kyle the Caiman [???] (PC, Android and Ouya)
    KTC: King Crocko's Mystic Maze [???] (PC, Android and Ouya)

  3. #3
    Super Moderator curmudgeon's Avatar
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    Default Re: Drawing Objects on Screen

    You would draw your image in the paintComponent(...) method of a JPanel or other JComponent derived class. You could loop through your ArrayList in this paintComponent method.

  4. #4
    Member Gravity Games's Avatar
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    Default Re: Drawing Objects on Screen

    How would I do that? Level.java's draw method is called by a JPanel if thats what you mean.
    Current Projects (and planned release dates):

    Chomp's Wacky Worlds [???] (PC, Android and Ouya)
    Kyle the Caiman [???] (PC, Android and Ouya)
    KTC: King Crocko's Mystic Maze [???] (PC, Android and Ouya)

  5. #5
    Super Moderator curmudgeon's Avatar
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    Default Re: Drawing Objects on Screen

    Quote Originally Posted by Gravity Games View Post
    How would I do that? Level.java's draw method is called by a JPanel if thats what you mean.
    Have you gone through the Swing graphics/drawing tutorial? I'm meaning nothing more than is described there.

    Your levels are held by a class derived from JComponent correct? Simply draw the level in that object's paintComponent method. The background image would likely be in a BufferedImage, and the sprites would be drawn individually by going through the array list.

  6. #6
    Member Gravity Games's Avatar
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    Default Re: Drawing Objects on Screen

    Oh, I'm already doing that (I had no problem when drawing one object), the problem is defining the individual objects of the arraylist. For example:

    The array list contains (Object 1, object 2, object 3)

    and the loop needs to do this:

    object1.render
    object2.render
    object3.render

    How do I call the objects in the ArrayList of Tile objects?
    Current Projects (and planned release dates):

    Chomp's Wacky Worlds [???] (PC, Android and Ouya)
    Kyle the Caiman [???] (PC, Android and Ouya)
    KTC: King Crocko's Mystic Maze [???] (PC, Android and Ouya)

  7. #7
    Super Moderator curmudgeon's Avatar
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    Default Re: Drawing Objects on Screen

    In the paintComponent method, loop through the ArrayList calling render on the components in the list, passing in the Graphics object.

  8. #8
    Member Gravity Games's Avatar
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    Default Re: Drawing Objects on Screen

    Ah, thank you. I had forgot to use .get to access the components. That was the problem.
    Current Projects (and planned release dates):

    Chomp's Wacky Worlds [???] (PC, Android and Ouya)
    Kyle the Caiman [???] (PC, Android and Ouya)
    KTC: King Crocko's Mystic Maze [???] (PC, Android and Ouya)

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