Cocos2D Asteroids

For school I have to make a game for my iPod touch, I chose to do an asteroids game. I have just started with cocos2d but have read the wenderlich blog. I wanted to use chipmunk in my game, i want realisitc motion of the ship. Is there a tutorial on crea开发者_StackOverflowting the asteroids motion?

Thanks.

Simple Way

Learn a bit about vectors. http://chortle.ccsu.edu/VectorLessons/vectorIndex.html

Movement is usually calculated by adding a vector scaled by a time delta to the current position. (Math talk makes simple things so complicated).

Basically: new_Pos = old_Pos + mov_Vec * time_delta

So by changing the mov_Vec you can increase/decrease speed.

You can also do it on x,y new_x = old_x + mov_x * time_delta

Using Physics Library

If you are using a physics library, you can apply force to an object to move it. You can also set the angular velocity if you want it to rotate.

If you were using Box2d you would do something like this:

body->ApplyImpulse( b2Vec2(1,1), body->GetWorldCenter() );

There's a difference between applying force and an impulse in box2d

Some sites to check out

• http://gpwiki.org/
• http://www.gamedev.net/
• http://www.devmaster.net/
• http://box2d.org/

Airship motion in space is pretty easy to simulate... I don't think you need a library for that. The ship has a velocity vector: depending on your input method, you shall only add a vector to change the speed (or reduce modulo when braking, if braking is allowed). Just limit the max modulo of the ship, and you're done.

Sorry if this isn't really a reply to your answer. HIH