android andengine scene is slow when attache many childs to it?

Question

I am working on andengine application. In this i am inserting the sprites on user click and drawing a circle by using small rectangles. I create many rectangles by loop and arrange them on a path of circle, so it look like a circle. But the problem is screen is responding slowly and looks like hanging.Can anybody suggest how can i make it smoother.. Here is my code.

//variables

private static final FixtureDef FIXTURE_DEF = PhysicsFactory.createFixtureDef(1, 0.5f, 0.5f);


    private BitmapTextureAtlas mBitmapTextureAtlas;

    private TiledTextureRegion mBoxFaceTextureRegion;

    private Scene mScene;

    private PhysicsWorld mPhysicsWorld;

//scene method

@Override
    public Scene onCreateScene() {
        this.mEngine.registerUpdateHandler(new FPSLogger());

        this.mScene = new Scene();
        this.mScene.setBackground(new Background(0, 0, 0));
        this.mScene.setOnSceneTouchListener(this);

        this.mPhysicsWorld = new PhysicsWorld(new Vector2(0, SensorManager.GRAVITY_EARTH), false);

        final VertexBufferObjectManager vertexBufferObjectManager = this.getVertexBufferObjectManager();
        final Rectangle ground = new Rectangle(0, CAMERA_HEIGHT - 2, CAMERA_WIDTH, 2, vertexBufferObjectManager);
        final Rectangle roof = new Rectangle(0, 0, CAMERA_WIDTH, 2, vertexBufferObjectManager);
        final Rectangle left = new Rectangle(0, 0, 2, CAMERA_HEIGHT, vertexBufferObjectManager);
        final Rectangle right = new Rectangle(CAMERA_WIDTH - 2, 0, 2, CAMERA_HEIGHT, vertexBufferObjectManager);

        final FixtureDef wallFixtureDef = PhysicsFactory.createFixtureDef(0, 0.5f, 0.5f);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, ground, BodyType.StaticBody, wallFixtureDef);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, roof, BodyType.StaticBody, wallFixtureDef);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, left, BodyType.StaticBody, wallFixtureDef);
        PhysicsFactory.createBoxBody(this.mPhysicsWorld, right, BodyType.StaticBody, wallFixtureDef);

        this.mScene.attachChild(ground);
        this.mScene.attachChild(roof);
        this.mScene.attachChild(left);
        this.mScene.attachChild(right);
        drawLine();
        this.mScene.registerUpdateHandler(this.mPhysicsWorld);

        return this.mScene;
    }

//In drawline method:

private void drawLine() {


        float x1,y1,x2=1,y2=1;
        float r=100;
        float xCenter=300,yCenter=300;
        Rectangle rectTest;

        for(double i=0;i<5;i+=.01){
                x1 = (float) (xCenter + r * Math.cos(i));  
                y1 = (float) (yCenter + r * Math.sin(i));

                System.out.println("RECT x1="+x1);
                System.out.println("RECT y1="+y1);
                System.out.println("RECT x2="+x2);
                System.out.println("RECT y3="+y2);

             rectTest = new Rectangle(x1,y1,1,1,getVertexBufferObjectManager());

            rectTest.setColor(Color.RED);
            FixtureDef wallFixtureDef = PhysicsFactory.createFixtureDef(0,
                    0.1f, 0.1f);
            PhysicsFactory.createBoxBody(this.mPhysicsWorld, rectTest,
                    BodyType.StaticBody, wallFixtureDef);
            this.mScene.attachChild(rectTest);

        }
}

Answer 1

The problem is probably that you are creating 500 dynamic body objects using Box2D. Box2D, or any physics engine, is relatively costly on a mobile platform. And simulating 500 colliding bodies is pushing the limit of what a mobile processor can handle. Try using under 50 objects to define your circle.