Part 14. Implementing traps, different platform types.

• Platform 1 - normal static platform, no special features.
• Platform 2 - trap platform, fall down after 0.2 sec. after contact with player.
• Platform 3 - falling down immediately if there is contact with player.

Doing it will be really easy, since we already created code responsible for loading levels, parsing level file and creating game scene. If you remember, we set different user data`s for bodies of each platform type ("platform1", "platform2" and "platform3") those user data`s will help us to recognise what events should we execute, every time there will be contact between certain bodies/fixtures. We are going to check in our Contact Listener inside GameScene.

1. Platform - falling immediately. Lets think how can we achieve it easily. At beginning, by default we are creating our platforms bodies as a Static body type, which means it does not react with any forces, such as gravity, to make our body fall, we simply have to change its type to Dynamic.

• go to our GameScene, our contact listener code.
• inside beginContact insert new check (contact between "player" and "platform3")

if (x1.getBody().getUserData().equals("platform3") && x2.getBody().getUserData().equals("player"))
{
    x1.getBody().setType(BodyType.DynamicBody);
}

What it does? It simply changes our platform3 body type to Dynamic, which means it will be also affected by gravity, which means will fall down.

2. Platform - falling with delay.

• put this code inside beginContact, just like we did with previous platform.

if (x1.getBody().getUserData().equals("platform2") && x2.getBody().getUserData().equals("player"))
{
    engine.registerUpdateHandler(new TimerHandler(0.2f, new ITimerCallback()
    {                                    
        public void onTimePassed(final TimerHandler pTimerHandler)
        {
            pTimerHandler.reset();
            engine.unregisterUpdateHandler(pTimerHandler);
            x1.getBody().setType(BodyType.DynamicBody);
        }
    }));
}

What it does? After contact between player and platform2, we register new timer handler, and after 0.2 seconds we are setting platforms body to Dynamic. We achieved simple delay.

Special notes: