I don't think so, not without modifying Box2D and recompiling Löve anyway. If you don't want a dynamic body to be affected by gravity, you can use Body:setGravityScale (set it to zero). You can also make the bullets sensors (Fixture:setSensor) if you just need basic collision detection. That works,...

I set the type of bullets to be 'kinematic',ground and walls 'static'.I know that kinematic bodies only collide with dynamic bodies,is there a way to change that?Or if I set bullets to be dynamic,they immediately drop into the ground when I shoot,I set the mass of them to be 0,it turns out that does...