Simulate a Balloon in Box2D, iPhone or ANDROID

By | April 12, 2012

Hello………
Sometimes you may want your body to act against the gravity of the world.
One method to do this is described below.
First what you have to do is to make a body in the shape of a circle and give it the image of a balloon as the userdata.

Then in the tick function write this code.
This method of applying the force is called “The antagonist forces method”
By this method we are giving an upward force to only our balloon body irrespective of the gravitational force.
After running the code you will see your body floating in air like a balloon.

for (b2Body* b = world->GetBodyList(); b; b = b->GetNext())
   {
        if (b->GetUserData() != NULL) {
               if (b==baloonBody) {
                         b->ApplyForce( b2Vec2(0.0,9.8*b->GetMass()),b->GetWorldCenter()); // here 0.0 is x, 9.8 is y (the gravity)
               }
         }
   }

Note: Try to change the value 9.8 to higher if you have given your world’s gravity as 9.8. It will produce a balloon effect.
Please leave your comments if this post was useful……….

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