What are the addCompound's parameter? #34

Hi, when I try to use the API "addCompound" in World.hpp to create "Compound" object, I have no idea about its parameter. The reason I want to create this object is that I want to create a "slope" or "wall" or "gap" terrain in order to train in raisimGym.

Compound *addCompound(const std::vector<Compound::CompoundObjectChild> &children,
                        double mass,
                        const Mat<3, 3>& inertia,
                        CollisionGroup collisionGroup = 1,
                        CollisionGroup collisionMask = CollisionGroup(-1));

Well, I mean what kind of type Compound::CompoundObjectChild is? I have seen in your Compound.hpp. It used the reference to a list while there is no notation about this "list"

struct CompoundObjectChild {
    ObjectType objectType;
    Vec<4> objectParam;
    std::string material;
    Transformation trans;
  };
  Compound(const std::vector<CompoundObjectChild>& list, double mass, Mat<3,3> inertia);

So, what "list" should I give? Maybe a urdf path? I have no idea and hope for your reply ASAP.
Thanks in advance.
@jhwangbo @tomlankhorst @vastsoun