Jump to content
  • Advertisement
Sign in to follow this  

OpenGL OpenGL Texture Problem

This topic is 2798 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hello everyone. This is my first post here but I have lurked for a while to help myself out with some problems. I finally have one that I can't find a solution to. I am writing a multiplayer game in java using LWJGL and I just recently converted my client textures to not be hardcoded in, but to be loaded from a sprite sheet. All textures are loaded using slick-util's TextureLoader class.

The sprite sheet is loaded at initialization in my ResourceManager class and this class also loads the positions of all of the textures on this sheet and I use these relative positions in order to render each texture from the main sheet.

My problem is that it displays a very weird image consisting of unicode characters, as shown in the attached image. If I instead load the sprite sheet on every update loop, it then displays correctly. Obviously I don't want to load the textures each loop and this causes a MemoryOverflow exception. But when I instantiate this class at initialization the problem occurs. I can't seem to figure this out. It seems as if the texture is no longer in memory, although it should be.

Thanks in advance.

Share this post

Link to post
Share on other sites
We'll probably need to see some code to help.

The unicode thing might just be from another texture of font typeface, so maybe you're binding the wrong texture when rendering, or overwriting your texture with a font texture sometime after initialization?

Share this post

Link to post
Share on other sites
The unicode isn't from a previously bound texture because there aren't any. And I know that it does in fact work, but only when the resource manager is instantiated every loop. However, not when instantiated once. It also works when the textures are each hard coded in. But not on a sheet.

Code snippet of the render/ update loop which updates current game state

public static ResourceManager r;
public static void main(String[] args)


while (! Display.isCloseRequested()) // Main loop






Code for render method of gamestate manager

public void render(ResourceManager r) {





public class ResourceManager {
protected HashMap<String , Texture2D> loadedTextures = new HashMap<String , Texture2D>();
public Texture sheet;

public ResourceManager(){
try {
sheet = TextureLoader.getTexture("PNG", ResourceLoader.getResourceAsStream("resources/sheet.png"));
} catch (IOException e) {
// TODO Auto-generated catch block
private void loadTextureList(){



FileInputStream fstream = new FileInputStream("resources/sheet.txt");

DataInputStream in = new DataInputStream(fstream);
BufferedReader br = new BufferedReader(new InputStreamReader(in));
String strLine;

while ((strLine = br.readLine()) != null) {

StringTokenizer str = new StringTokenizer(strLine," = \n");
String name = str.nextToken();
int x = Integer.parseInt(str.nextToken());
int y = Integer.parseInt(str.nextToken());
int texWidth = Integer.parseInt(str.nextToken());
int texHeight = Integer.parseInt(str.nextToken());

Texture2D next = new Texture2D(x , y , texWidth , texHeight , sheet.getImageHeight() , sheet.getImageWidth());

System.out.println("Texture: " + name + " added with X: " + x + " Y: " + y + " Height: " + texHeight + " Width: " + texWidth);
loadedTextures.put(name , next);


}catch (Exception e){

public Texture2D getTexture(String s){
if(loadedTextures.get(s) == null){
System.out.println("Texture Not Found: " + s);
return loadedTextures.get("notFound");
return loadedTextures.get(s);



public class Texture2D
//public Texture texture;
public Vector2 size;
public float x, y, height, width;

public Texture2D(float x , float y , float height , float width , float heightSheet , float widthSheet)
size = new Vector2(height, width);
setTextureOffsets(x , y , height , width , heightSheet , widthSheet);


public void setTextureOffsets(float x , float y , float height , float width , float heightSheet , float widthSheet){

this.x = x / widthSheet;
this.y = y / heightSheet;
this.height = height / heightSheet;
this.width = width / widthSheet;

//public void render();

And finally the render method of the Sprite class which is the super class of all drawn objects.

public void render(Camera camera , ResourceManager r) {
texture = r.getTexture(textureID);

size = new Vector2f((texture.size.x * scale.x) / camera.zoom, (texture.size.y * scale.y) / camera.zoom);
Vector2f newPosition = camera.screenToWorld(position);
newPosition = new Vector2f(newPosition.x - (size.x / 2), newPosition.y - (size.y / 2));
GL11.glTexCoord2f(texture.x, texture.y);//Upper Left
GL11.glVertex2f(newPosition.x, newPosition.y);
GL11.glTexCoord2f(texture.x + texture.width, texture.y);//Upper Right
GL11.glVertex2f(newPosition.x + size.x, newPosition.y);
GL11.glTexCoord2f(texture.x + texture.width, texture.y + texture.height);//Lower Right
GL11.glVertex2f(newPosition.x + size.x, newPosition.y + size.y);
GL11.glTexCoord2f(texture.x, texture.y + texture.height);//Lower Left
GL11.glVertex2f(newPosition.x, newPosition.y + size.y);


That's everything that affects this problem. Thanks for the reply.

Share this post

Link to post
Share on other sites
Okay by moving some code around, I've reduced the problem down to being that the sheet variable is being overwritten or otherwise modified. If I load the sheet and write it to the ResourceManager it displays correctly. This still requires loading the textures from file every loop and that is ridiculous. This only started when I began loading the sheet as a single variable, instead of many hardcoded textures.

Share this post

Link to post
Share on other sites
Do you make sure that OpenGL context is initialized before you try to load textures? I see you're originally loading in the constructor of the ResourceManager. If that is initialized before you setup the context then it won't work.

Also have you tried putting glGetError's in your code? Those work great for picking out illegal actions.

Share this post

Link to post
Share on other sites
Sign in to follow this  

  • Advertisement

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

GameDev.net is your game development community. Create an account for your GameDev Portfolio and participate in the largest developer community in the games industry.

Sign me up!