LibGdx View Port, resolutions, sprite size - libgdx

Question

Helllo, im new to libgdx, i need some help, if my desktoplauncher resolution is 480x320, sprite takes 80% of the screen, but if 1280x720, sprite is small, i need to make it look the same at all resoltions so how do i do this? may be easy for you, but not for my, im using libgdx 1.3.1
this is my libgdx code:
SpriteBatch batch;
Texture img;
Sprite mysprite;
#Override
public void create ()
{
batch = new SpriteBatch();
img = new Texture("badlogic.jpg");
mysprite = new Sprite(img);
stage = new Stage(new StretchViewport(480, 320));
}
StretchViewport myviewport = new StretchViewport(480, 320);
public void resize(int width, int height)
{
// use true here to center the camera
// that's what you probably want in case of a UI
stage.setViewport(myviewport);
stage.getCamera().position.set(640/2, 480/2, 0);
}
private Stage stage;
#Override
public void render ()
{
Gdx.gl.glClearColor(1, 0, 0, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.begin();
mysprite.draw(batch);
batch.end();
}

Answer 1

You are allready using the right thing: Viewport.
There are different Viewport classes, some of them support working with a virtual screen size, which is what you are looking for.
What is a virtual screen size? Well it is the screen size your code is working with and which is then scaled up to match the real resolution.
Basicly you can work with your own units and they are then automatically scaled up to match pixels.
I guess in your case there are 2 possible Viewport-types:
- StretchViewport supports virtual screen sizes and scales it up to match the real screen size and the real aspect ratio. If the real aspect ration does not match the virtual one the Sprites will be stretched, which could look strange.
- FitViewport is the same as the StretchViewport, but it will keep the aspect ratio. If the real aspect ration does not match the virtual one, black borders will appear.
How to use it:
First you need to create it:
myViewport = new StretchViewport(VIRTUAL_WIDTH, VIRTUAL_HEIGHT);
Then set the Stages Viewport:
stage = new Stage(myViewport);
In the resize method you need to update your Viewport:
myViewport.update(width, height);
Thats all.
The stage now uses the Viewport and its camera to render. You don't need to touch the camera, unless you need to move it arround.
So your errors are:
stage = new Stage(new StretchViewport(480, 320));
Which creates a new StretchViewport you don't store/use.
stage.setViewport(myviewport);
You only need to set it once, when you create the stage
You never call update(width, height) for the Viewport.