box2d ship-game beginner questions: applyForce, gravity + water

I'm just starting with cocos2d + box2d. I would love to create a simple 2d ship game where you look from top(from the sky) down at the sea with the ships.

Could someone give me a very very basic exampl开发者_高级运维e, how to apply wind to my world? Do I have to applyForce to each ship body?

And what about the gravity? Since it goes straight down, should I set it to 0? gravity.Set(0.0f, 0.0f)? It actually would pull down the ship..

Should I somehow deal with the water? e.g with density of it?

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you would probably have to detect where the ships are and then apply force on them somehow.

and yes set gravity to 0.

and water wouldn't have to be an object at all. just like a background image.

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If you are looking from the top and want to apply wind force to all your ships you can use gravity vector. In this case wind force will be applied to your objects automatically.

If there are other dynamic objects on the scene then it's a good idea to keep the list (std::list or NSMutableArray) of pointers to all your ships. Notice, that by default box2D is clearing all the forces each simulation step. You can disable this property or apply forces manually each simulation step