Cobrapitz Cobrapitz - 9 months ago 38
C++ Question

Box2d strange behavior when 2 bodies colliding while rotating

I am developing a game recently (it's should be a space ship game like reassembly).
So my situation:
- i got 2 bodies with 0 restitution and 0 friction
- when they are colliding they slide and lose velocity because of my lineardumping
- but when 1 of them both is rotating (with setangularvelocity), they bounce off with a very high velocity and i can't figure out why they even bounce this hard.

( and i read that there should just be a little bouncing even if there is no restitution, but i am not expecting something like this)

here's some code:

b2PolygonShape shape;

b2BodyDef def;
def.type = b2_dynamicBody;

b2FixtureDef fix;
fix.density = 1.f;
fix.restitution = .0f;
fix.friction = 0.f;

bbody = world->CreateBody(&def);
bbody2 = world->CreateBody(&def);


// PIXELPERMETER is the scaling from pixels to meter. (30)
shape.SetAsBox(32 / PIXELPERMETER/*=30*/, 32 / PIXELPERMETER);

fix.shape = &shape;

bbody2->SetTransform(b2Vec2(-100 / PIXELPERMETER, 0), 0);


Maybe you should try to tweak the mass data of your bodies ?

b2MassData massData; massData.mass = 50; //Just tweak me massData.I = 1; //Just never set me to 0 if you don't want to have nAn propagating = b2Vec2_zero; bbody->SetMassData(&massData);