CODEWITHSUNDEEP
libgdx
kifcaliph
kifcaliph

Reputation: 321

How to draw a line using libgdx?

I am trying to draw some lines for debugging using libgdx but I failed. this is my code

public class MainMenu extends Screen implements InputProcessor {

private OrthographicCamera camera;
SpriteBatch myBatch;
ShapeRenderer shapeDebugger;

public MainMenu(Game game) {
    super(game);
    camera= new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    camera.setToOrtho(true, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    camera.update();}

@Override
public void render(float delta) {
    Gdx.gl.glClearColor(0, 0, 0, 1);
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

    myBatch.begin();
    stage.draw();
    Gdx.gl10.glLineWidth(10);
    shapeDebugger.setProjectionMatrix(camera.combined);
    shapeDebugger.begin(ShapeType.Line);
    shapeDebugger.setColor(1, 1, 1, 1);
    shapeDebugger.line(2, 2, 5, 5);
    myBatch.end();
    }
}

I get an error from line

shapeDebugger.setProjectionMatrix(camera.combined);

@Pranav008

thank you very much. I didn't expect that I need to initiate it. but I've got a true problem. I draw the line to center of the game screen like this.

    Gdx.gl10.glLineWidth(2);
    shapeDebugger.setProjectionMatrix(camera.combined);
    shapeDebugger.begin(ShapeType.Line);
    shapeDebugger.setColor(1, 1, 1, 1);
    shapeDebugger.line(Gdx.graphics.getWidth()/2, 0,Gdx.graphics.getWidth()/2, Gdx.graphics.getHeight());
    shapeDebugger.end();

when I try to resize the screen it doesn't update the to center it goes far away to right.

Upvotes: 4

Views: 13288

Answers (4)

Hitesh Sahu
Hitesh Sahu

Reputation: 45072

Define & initialize ShapeRenderer

ShapeRenderer shapeDebugger;

@Override
public void create() {
    shapeDebugger = new ShapeRenderer();
 ...

Draw line in render callback

    @Override
    public void render() {
        //render scene

        Gdx.gl.glClearColor(69f / 255, 90f / 255, 100f / 255, 1);
        Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

    ... 
   shapeDebugger.setProjectionMatrix(camera.combined);
        shapeDebugger.begin(ShapeRenderer.ShapeType.Line);
        Gdx.gl.glLineWidth(10 / camera.zoom);
        shapeDebugger.setColor(1, 0, 0, 1);
        shapeDebugger.line(screenWidth / 2, 0, screenWidth / 2, screenHeight);
        shapeDebugger.line(0, screenHeight / 2, screenWidth, screenHeight / 2);
        shapeDebugger.end();

Upvotes: 0

mewiki
mewiki

Reputation: 135

My answer is mayby too late for you, but for people how have the same positioning problems.

Your second question about the position after a resize is because the viewport did not change. Aldo your window size changed your application stil is using the same pixel size set on create by the function camera.setToOrtho

Update the view port on a resize!

//-----------------------------------------------------------------
@Override
public void resize (int width, int height) {
    camera.setToOrtho(true, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    camera.update();        
}

Upvotes: 1

Pranav008
Pranav008

Reputation: 1223

You must have got nullpointerException because you haven't made any object of ShapeRenderer. Insert this line in your constructor. 

shapeDebugger=new ShapeRenderer();

Upvotes: 5

Nine Magics
Nine Magics

Reputation: 737

Remember that nesting Shaperender with a SpriteBatch may cause problems.

Check this link.

Upvotes: 3

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