Why cant I use slick-util with image IO and bufferedImage

Question

My problem is that I get errors when I use

texture = TextureLoader.getTexture("PNG", ResourceLoader.getResourceAsStream("TEXTURE PATH HERE"));

it gives me these errors:

Exception in thread "main" java.lang.RuntimeException: No OpenGL context found in the current thread.
    at org.lwjgl.opengl.GLContext.getCapabilities(GLContext.java:124)
    at org.lwjgl.opengl.GL11.glGetError(GL11.java:1277)
    at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:226)
    at org.newdawn.slick.opengl.InternalTextureLoader.getTexture(InternalTextureLoader.java:184)
    at org.newdawn.slick.opengl.TextureLoader.getTexture(TextureLoader.java:64)
    at org.newdawn.slick.opengl.TextureLoader.getTexture(TextureLoader.java:24)
    at game.Map.Init(Map.java:34)
    at game.Game.start(Game.java:17)
    at game.Game.main(Game.java:63)

My code uses ImageIO, Buffered Image and image.getRGB(); But it also uses the Slick-Util library for loading textures to render.

The full code for the Map.java class is:

`
package game;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;


import javax.imageio.ImageIO;

import org.lwjgl.LWJGLException;
import org.lwjgl.opengl.Display;
import org.lwjgl.opengl.DisplayMode;
import org.lwjgl.opengl.GL11;
import org.newdawn.slick.Color;
import org.newdawn.slick.opengl.Texture;
import org.newdawn.slick.opengl.TextureLoader;
import org.newdawn.slick.util.ResourceLoader;



public class Map {


    int mapSize=100;
    int[] Tiles = new int[mapSize+1];
    int Tile;

    public Texture texture;

    public void Init()
    {
        try {
            // load texture from PNG file
            texture = TextureLoader.getTexture("PNG", ResourceLoader.getResourceAsStream("res/Tiles/Grass.png"));

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

     public void LoadMap()
        {


            File file= new File("res/map.png");
              BufferedImage image = null;
            try {
                image = ImageIO.read(file);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            for(int Y = 0;Y<image.getHeight();Y++){
                for(int X = 0;X<image.getWidth();X++){

              int clr=  image.getRGB(X,Y); 
              int  red   = (clr & 0x00ff0000) >> 16;
              int  green = (clr & 0x0000ff00) >> 8;
              int  blue  =  clr & 0x000000ff;
              if(red==0&&green==0&&blue==0){
                  Tiles[Tile]=0;
              }
              if(red==255&&green==0&&blue==0){
                  Tiles[Tile]=1;
              }
              if(red==0&&green==255&&blue==0){
                  Tiles[Tile]=2;
              }
              if(red==0&&green==0&&blue==255){
                  Tiles[Tile]=3;
              }
              Tile++;
            }
            }
            for(int i = 0;i<mapSize;i++)
            {
                System.out.println(Tiles[i]);
            }


        }
     public void RenderMap()
     {

     }

}
`

So all I want to know is how can I fix this error and draw the textures down in the

 void Render()
    {

    }

method.

Thanks, Griffin.

Answer 1

I hope this clarifies it for you. I've noticed you're importing lwjgl, I take it you want more functionality than what Slick 2D is offering? I would need to see your lwjgl construction to comment further...

In a normal Slick 2D setup with BasicGame, you would do something similar to this:

import java.io.IOException;
import org.newdawn.slick.*;
import org.newdawn.slick.opengl.*;

public class TextureTest extends BasicGame
{
    private Texture texture;
    private Image grass;

    public TextureTest()
    {
        super("Texture Load Test");
    }

    @Override
    public void init(GameContainer container) throws SlickException
    {
        try
        {
            // load texture from PNG file
            texture = TextureLoader.getTexture("PNG", getClass().getResourceAsStream("grass.png"));
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        grass = new Image(texture);     
    }

    @Override
    public void update(GameContainer container, int delta)
            throws SlickException
    {
    }

    @Override
    public void render(GameContainer container, Graphics g)
            throws SlickException
    {   
        grass.draw();
    }

    public static void main(String[] args) throws SlickException
    {
        TextureTest game = new TextureTest();
        AppGameContainer app = new AppGameContainer(game);
        app.setAlwaysRender(true);
        app.start();
    }
}

Answer 2

Are you trying to load images into OpenGL before you create an OpenGL context (as in, open the game window via Slick)? That's not going to work.