Question

I’m having a problem with a simple 2d tile-based engine I’m working on. On my home computer (Windows 7 64bit, jogl 1.1.1) the textures bind properly to the tiles but on my laptop (Windows Vidta 32bit, jogl 1.1.1) they appear broken.

The sprites image is 600×100 (each sprite being 100×100).

Here is the textureManager class that I’m using.

public class TextureManager {

    private static Texture textureAtlas;
    private static Map<String, TextureCoords> locations;
    private static String imageName;

    public TextureManager() {

        locations = new HashMap<String, TextureCoords>();
    }

    public static void loadAtlas(String name) {

        if(textureAtlas != null) {

            if(imageName == name) return;

            textureAtlas.dispose();
        }

        imageName = name;

        try {

            textureAtlas = TextureIO.newTexture(new File("textures/" + name + ".png"), true);
        }
        catch (GLException e) {

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

            e.printStackTrace();
        }

        setAtlasLocations();
    }

    private static void setAtlasLocations() {

        locations.put("blank", textureAtlas.getSubImageTexCoords(0, 0, 100, 100));
        locations.put("tree1", textureAtlas.getSubImageTexCoords(100, 0, 200, 100));
        locations.put("tree2", textureAtlas.getSubImageTexCoords(200, 0, 300, 100));
        locations.put("tree3", textureAtlas.getSubImageTexCoords(300, 0, 400, 100));
        locations.put("rock", textureAtlas.getSubImageTexCoords(400, 0, 500, 100));
    }

    public static void bindTexture() {

        textureAtlas.bind();
    }

    public static TextureCoords getCoords(String name) {

        return locations.get(name);
    }
}

This is the rendering code:

    public void draw(GL gl) {

        gl.glEnable(GL.GL_TEXTURE_2D);

        TextureManager.bindTexture();

        int width = map.width();
        int height = map.height();

        float x = InterfaceManager.mapX;
        float y = InterfaceManager.mapY;

        gl.glTranslatef(x, y - height, 0);

        gl.glBegin(GL.GL_QUADS);

        gl.glNormal3f(0.0f, 0.0f, 1.0f);
        gl.glColor4f(1.0f, 1.0f, 1.0f, 1.0f);

        for(int w = 0; w < width; w++) {

            for(int h = 0; h < height; h++) {

                TextureCoords coords = getCoord(map.getTileType(w, h));

                gl.glTexCoord2f(coords.left(), coords.bottom());
                gl.glVertex3i(w, h, 0);
                gl.glTexCoord2f(coords.right(), coords.bottom());
                gl.glVertex3i(w+1, h, 0);
                gl.glTexCoord2f(coords.right(), coords.top());
                gl.glVertex3i(w+1, h+1, 0);
                gl.glTexCoord2f(coords.left(), coords.top());
                gl.glVertex3i(w, h+1, 0);
            }
        }

        gl.glEnd();

        gl.glTranslatef(-x, -y + height, 0);

        gl.glDisable(GL.GL_TEXTURE_2D);
    }

    private TextureCoords getCoord(int tileType) {

        if(tileType == 0) return TextureManager.getCoords("blank");
        else if(tileType == 1) return TextureManager.getCoords("rock");
        else if(tileType == 2) return TextureManager.getCoords("tree1");
        else if(tileType == 3) return TextureManager.getCoords("tree2");
        else if(tileType == 4) return TextureManager.getCoords("tree3");
        else return TextureManager.getCoords("blank");
    }

I know opengl is supposed to be platform independent, and since I’m using the same versions of opengl on both, I’m assuming there’s probably a bug in my code.

Hopefully someone more experienced with it can help me out with this problem. Thanks!

EDIT: Here is a picture of the skewed result.

The trees along the top and right side is actually supposed to be the rock in the sprite below.

This is the sprite file:

Answer 1

The automatically generated mipmaps by OpenGL were causing the problem. Changing the below line to not allow auto mipmapping fixes the problem.

textureAtlas = TextureIO.newTexture(new File("textures/" + name + ".png"), false);

If anyone would like to comment on how i should create my sprite file to allow auto mipmapping, or if this should even be on, please do 🙂

With mipmapping off, as i move the character around, some tiles get a black line beneath them. I’ll have to figure out how to make the sprite image mipmap-able.

EDIT: Make the file square and to the power of 2.