class Repulsor{
  Vec3D pos;
  float radius;
  float multiplier;

  Repulsor(Vec3D pos, float radius, float multiplier){
    this.pos = new Vec3D(pos);
    this.radius = radius;
    this.multiplier=multiplier;


  }

  Vec3D steeringForce(Particle3D p){
    Vec3D repulsed = p.pos.sub(pos);
    float r = repulsed.size;

    if (r>radius){
      return new Vec3D();
    }
    else{
      repulsed = repulsed.normalize();
      repulsed = repulsed.mul(multiplier*(radius-r));
      Vec3D steer = repulsed.sub(p.vel);
      line(pos.x,pos.y,pos.z,p.pos.x,p.pos.y,p.pos.z);
      return steer;    
    }



  }


}