Posted by goosey on Mar 19, 2021; 4:42am
URL: https://forum.jogamp.org/Trouble-with-TextureCoords-for-tilesets-tp4041047.html

I am learning jogl so I can make my own 2d game.
All the textures for the tiles are stored in a single large tilesheet. I tried to use Texture.getSubImageTexCoords() to draw a single tile from the tilesheet, but the result was all warped:



As you can see, the upper left triangle that makes up the quad is warped even though I'm not really doing any perspective-changing or anything like that.
What I would like is for the tile to just be displayed normally but when I looked online for solutions I couldn't find anything. I'm pretty sure that it's just something really stupid that I don't know how to do .

here is some code that reproduces the issue:

public class TestSubImage {
    private GLU glu = new GLU();
    private GLCanvas mainCanvas;
    private Texture texture;
    private TextureCoords tc;

    class Listener implements GLEventListener {
        public void init(GLAutoDrawable drawable) {
            // Load texture
            try {
                texture = TextureIO.newTexture(TestSubImage.class.getResource("/images/sheet.png"), false, null);
                texture.setTexParameteri(drawable.getGL(), drawable.getGL().GL_TEXTURE_MAG_FILTER, drawable.getGL().GL_NEAREST);
                tc = texture.getSubImageTexCoords(0, 16, 16, 32); // sub texture coords
            } catch (IOException e) {
                e.printStackTrace();
            }

            // Set up
            drawable.getGL().glClearColor(0.3f, 0.3f, 0.3f, 0);
            glu = new GLU();
            glu.gluOrtho2D(0, 512, 512, 0);
        }

        public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {

        }

        public void dispose(GLAutoDrawable drawable) {
        }

        public void display(GLAutoDrawable drawable) {
            GL2 gl = drawable.getGL().getGL2();
            gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT);

            // where to draw the image
            int x = 100;
            int y = 100;
            int width = 200;
            int height = 200;

            gl.glColor3f(1, 1, 1);

            // Draw the image
            texture.enable(gl);
            texture.bind(gl);

            gl.glBegin(GL2.GL_QUADS);
            gl.glVertex2f(x, y);
            gl.glTexCoord2f(tc.left(), tc.bottom());
            gl.glVertex2f(x, y + height);
            gl.glTexCoord2f(tc.right(), tc.bottom());
            gl.glVertex2f(x + width, y + height);
            gl.glTexCoord2f(tc.right(), tc.top());
            gl.glVertex2f(x + width, y);
            gl.glTexCoord2f(tc.left(), tc.top());
            gl.glEnd();
            texture.disable(gl);
        }
    }

    private void run() {

        // Create window
        JFrame frame = new JFrame("Texture Coords Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Create profile and capabilities
        final GLProfile profile = GLProfile.get(GLProfile.GL2);
        GLCapabilities caps = new GLCapabilities(profile);

        // Now set up the main GLCanvas
        mainCanvas = new GLCanvas(caps);
        mainCanvas.addGLEventListener(new Listener());

        frame.getContentPane().add(mainCanvas);
        frame.setSize(512, 512);
        frame.setResizable(false);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        new TestSubImage().run();
    }
}

And the tilesheet I'm using (programmer art  don't judge).


Thanks in advance!!!