box2d-iphone

I'm making a game in which a certain object (modelled as a box2d body) has to follow a fixed path. Is there a way by which I can specify the path coordinates and make the object advance over it for each dt? Thanks Another option: Attach a mouse joint to your body Use setTarget method of the mouse joint to move the body You should use a Kinematic body, but you can't change its position manually, you have to change its speed for the dynamics and collisions to be applied correctly. I suggest the following algorithm: 1st - Calculate the position on the track that the body should be in on the next

I'm writing a game, and I need to make up a rope. I maked it by b2RopeJoint, but there I have not found an opportunity to make it elastic. Then I looked for b2DistanceJoint, everything is cool with the elasticity, but I can't find an ability to set a limit only to the maximum distance (without minimum one). How can I do it? Try this. -(void) CreateElasticRope { //=======Params // Position and size b2Vec2 lastPos = b2Vec2(4,4); //set position first body float widthBody = 0.35; float heightBody = 0.1; // Body params float density = 0.05; float restitution = 0.5; float friction = 0.5; // Distance

I'm attempting to create a "U" shape in Box2d (in Cocos2d) by joining 3 rectangles like so: |_| It sounds like joints are not the correct solution here since I don't want any movement so I have created a main body which is the middle bit and 2 fixtures for the sides. I've added the two sides to the middle bit like this: mainBody->CreateFixture(&leftFixtureDef); mainBody->CreateFixture(&rightFixtureDef); This works, however both side fixtures get added to the center of the mainBody. I can't seem to work out how to position the fixtures relative to the main body. Attaching a sprite/node to the

I'm newbie in box2d. Can you help me? I want to make gun (touch, move, stopped, ball flew). I make detection and rotation of gun, but I can't make popping of ball. How can I count velocity, which I need to set to the ball? Thank you very much The easiest way is to look at the direction the gun is pointing when you define the body, and use GetWorldVector to see how it has changed. For example if the gun is pointing directly upwards when you create the body, this would be the direction (0,1). Then you can use GetWorldVector at any time to get the current direction of that vector in world