box2d

As we always use the function in cocos2d,I can scale my sprite whenever I want.Can I do the same thing in box2d?For example, I created a circle shaped body,then I want to make it bigger. I tried reassign the m_radius after I created a circle,but not work. If you are simply assigning shape.m_radius to a new value, it will not work. You need to reference the shape object associated with the b2Fixture that you created for your object: fixture->GetShape()->m_radius = new_radius/PTM_RATIO; Hope this helps. 来源： https://stackoverflow.com/questions/9075359/can-i-scale-a-shape-in-box2d-as-sprite-do

I have a Box2D world with a mixture of static and dynamic bodies. On collisions, I can only get the positions of the dynamic ones. Is it possible to get the positions of static objects? N.b., this is a development of a previous question, Box2D: How to get the position of a sensor? I found a way - in the collision, the center of the AABB will give the position contact.GetFixtureA().GetAABB().GetCenter() You can get the position vector using the following code: b2Transform t = body->GetTransform(); b2Vec2 pos = b2Vec2(t.p.x,t.p.y); 来源： https://stackoverflow.com/questions/5666834/box2d-how-to-get

I have a ball (a dynamic body in the shape of a circle) that acts on a surface (trampoline) in the conditions of a gravity force. When the ball impacts the trampoline (drawn in the picture from point A to B) I would like to apply an impulse (normal to the trampoline surface) to the ball. The problem is that right now i use: b2Vec2 impulse = b2Vec2(0, [self fullMass]*[GameMaster sharedInstance].usrTrampolineForce); b2Vec2 impulsePoint = _body->GetWorldPoint(b2Vec2(0/PTM_RATIO, -1.0/PTM_RATIO)); _body->ApplyLinearImpulse(impulse, impulsePoint); Which sends the ball perpendicular(on the surface)

I was wondering how i can speed up whole game done with libgdx (for example after clicking a button). The way i have in my game is modify a timestep variable used in world.step(TIMESTEP, VELOCITYITERATIONS, POSITIONITERATIONS); but im now sure if it's a good idea. If there a any better way to archive that? When using Box2D you can speed up your game by modifying the physics step. One problem is that you should use a constant steptime. I use the following code below in my games: private float accumulator = 0; private void doPhysicsStep(float deltaTime) { // fixed time step // max frame time to

Question is simple so, no codes! If someone knows Box2D and SDL2, then, please tell me how to wrap SDL_Rect with b2body. Ofcourse, it requires to know the conversion of metre to pixel and vice versa. This is because Box2D measures distance in metres. Can you give me a simple expression or function to convert metres(of Box2D) to pixels or pixels to metres(of Box2D)? Can you give me a simple expression or function to convert metres(of Box2D) to pixels or pixels to metres(of Box2D)? Unfortunately, this isn't as simple as it sounds, for us. Because, if your game is on worms, then your game world