Random creation of balloons

[Alex.S]

Hello everybody!

My name is Alex. I am new here and i have a question. I have two balloons: one red and one blue, the thing is how can i spawn them on random locations along the x-axis??

[john2994]

i am also new to AndEngine and to programming but maybe i can help.
u cant do Random rnd = new Random();
after initialize your screen View with a name e.g GameView after print the balloon with balloon image and x considerations rnd.nextInt(GameView.getWidth()-balloon.getWidth) i think thats all

[Alex.S]

One more thing. I dont have just two balloons. I am planning that (many) balloons will be created at the bottom of the screen one by one and fly all the way up. This is something i dont know for sure how to code.

[OzLark]

bottom of the screen one by one and fly all the way up.

To make balloons fly, you need to apply a negative to gravity LinearVelocity or ApplyForce to the balloon bodies in your update loop - be careful though that your FPS does not effect your balloon speed.

[Alex.S]

Cant i just use MoveYModifier to make them fly upwards along the y-axis?? Because i would like to dont use physics in my first game.

[OzLark]

Yes, ignore my advice if you're not using physics.

It's much easier (as you suggest) if you don't need physics.

[Alex.S]

But that doesnt solve my question about random spawn of balloons at the bottom of the screen.

[OzLark]

You can calculate a random X location by using MathUtils.random(minX, maxX) and you can do this based on time using a registered update handler on your scene:

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Syntax: [ Download ] [ Show ]

Using java Syntax Highlighting

1. registerUpdateHandler(new TimerHandler(3.0f, true, new ITimerCallback() {
2.         @Override                                                            
3.         public void onTimePassed(final TimerHandler pTimerHandler) {                                                                                  
4.                 // do spawning here.    
5.         }
6. }));

Parsed in 0.031 seconds, using GeSHi 1.0.8.4

[Alex.S]

Can it look something like this:

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Syntax: [ Download ] [ Show ]

Using java Syntax Highlighting

1. registerUpdateHandler(new TimerHandler(3.0f, true, new ITimerCallback() {
2.  
3.                 @Override                                                            
4.  
5.                 public void onTimePassed(final TimerHandler pTimerHandler) {                                                                                  
6.  
7.                         // do spawning here.    
8.  
9.                 }
10.  
11.         }));
12.                 scene.attachChild(textScore);
13.                 scene.attachChild(blue_baloon);
14.                 scene.attachChild(red_baloon);
15.                 scene.registerTouchArea(red_baloon);
16.                 scene.registerTouchArea(blue_baloon);
17.                 scene.setTouchAreaBindingEnabled(true);
18.                 return scene;
19.         }

Parsed in 0.032 seconds, using GeSHi 1.0.8.4

Because thats giving me an error: the method registerUpdateHandler(TimeHandler) is undefined for the type BalloonpopActivity

[OzLark]

Call registerUpdateHandler() on the scene like:

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Syntax: [ Download ] [ Show ]

Using java Syntax Highlighting

1. scene.setTouchAreaBindingEnabled(true);
2. scene.registerUpdateHandler(new TimerHandler(3.0f, true, new ITimerCallback() {
3.                 @Override
4.                 public void onTimePassed(final TimerHandler pTimerHandler) {
5.                         //
6.                         // put your code to do spawning here.
7.                         //
8.                         scene.attachChild(blue_baloon);
9.                         scene.attachChild(red_baloon);
10.                         scene.registerTouchArea(red_baloon);
11.                         scene.registerTouchArea(blue_baloon);
12.                 }
13. }));

Parsed in 0.034 seconds, using GeSHi 1.0.8.4