libgdx: Other coordinatesystem when using textures

Question

I'm a little bit confused. I'm using libgdx for the first time and i have some problems with the coordinate systems. When i'm creating a texture and want to set the position, I do:

texture = new Texture("myGraphic.png", 0, 0); 

and my picture will be positioned at the left bottom corner.

But when I try to get the touch position with:

 if(Gdx.input.isTouched())
    {
        Vector3 tmp = new Vector3(Gdx.input.getX(),Gdx.input.getY(),0);
        System.out.println("Coord:" + " + " + tmp.x + " + " + tmp.y);
    }

I recognized that (0,0) is in the left top corner. So I tried camera.unproject(tmp) before my output, but then i will get only values between -1 and 1. How do i get the same coordinate system for all elements?

Answer 1

In Libgdx coordinate system for touch is y-down but for Screen or Image it's y-up.

Take a look of LibGDX Coordinate systems

If can use camera, set y-axis pointing up by camera.setToOrtho(false); and get world point by camera.unproject(vector3); method.

public class TouchSystem extends ApplicationAdapter {

    SpriteBatch batch;
    Texture texture;
    Vector3 vector3;
    OrthographicCamera camera;

    @Override
    public void create() {

        batch=new SpriteBatch();
        texture=new Texture("badlogic.jpg");
        vector3=new Vector3();
        camera=new OrthographicCamera();
        camera.setToOrtho(false);   // this will set screen resolution as viewport
    }

    @Override
    public void render() {

        Gdx.gl.glClearColor(0,0,0,1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

        batch.begin();
        batch.draw(texture,0,0);
        batch.end();

        if(Gdx.input.justTouched()) {

            vector3.set(Gdx.input.getX(),Gdx.input.getY(),0);
            camera.unproject(vector3);
            System.out.println("Coord:" + " + " + vector3.x + " + " + vector3.y);
        }
    }

    @Override
    public void dispose() {
        texture.dispose();
        batch.dispose();
    }
}