sim.combine = function(p1,p2) {
sim.newObj(
{x:obj[p1].pos.x*obj[p1].mass/(obj[p1].mass+obj[p2].mass)+obj[p2].pos.x*obj[p2].mass/(obj[p1].mass+obj[p2].mass),y:obj[p1].pos.y*obj[p1].mass/(obj[p1].mass+obj[p2].mass)+obj[p2].pos.y*obj[p2].mass/(obj[p1].mass+obj[p2].mass),z:obj[p1].pos.z*obj[p1].mass/(obj[p1].mass+obj[p2].mass)+obj[p2].pos.z*obj[p2].mass/(obj[p1].mass+obj[p2].mass)},
{x:(obj[p1].vel.x*obj[p1].mass+obj[p2].vel.x*obj[p2].mass)/(obj[p1].mass+obj[p2].mass),y:(obj[p1].vel.y*obj[p1].mass+obj[p2].vel.y*obj[p2].mass)/(obj[p1].mass+obj[p2].mass),z:(obj[p1].vel.z*obj[…