Method HandleSetQpos

Source/URLab/Private/Bridge/RpcDispatcher.cpp:2606–2749

============================================================================= set_qpos — manager-required runtime write to a single articulation's qpos. Two write modes: - Free-base 7-vec shortcut: len=7 and the first joint is mjJNT_FREE, writes only the 7 free-joint slots (xyz + quat). Skips dof joints. - Full per-articulation qpos: len matches the articulation's total qpos dim (sum of per-joint

// path so derived quantities (xpos, sensors) reflect the new state.
// =============================================================================
TSharedPtr<FJsonObject> FURLabRpcDispatcher::HandleSetQpos(const TSharedPtr<FJsonObject>& Req)
{
	AAMjManager* Mgr = OwnerMgr.Get();
	if (!Mgr || !Mgr->PhysicsEngine || !Mgr->PhysicsEngine->IsInitialized())
		return MakeError(TEXT("not_ready"), TEXT("Manager not initialised"));

	mjModel* m = Mgr->PhysicsEngine->GetModel();
	mjData* d = Mgr->PhysicsEngine->GetData();
	if (!m || !d)
		return MakeError(TEXT("not_ready"), TEXT("MjModel/MjData missing"));

	// target/target_by wire shape. target_by="actor_name" looks up via
	// the manager's GetArticulation (UE name match); default
	// "actor_id" walks ActorId.
	FString Target, By;
	Req->TryGetStringField(TEXT("target"), Target);
	Req->TryGetStringField(TEXT("target_by"), By);
	if (Target.IsEmpty())
	{
		return MakeError(TEXT("missing_field"),
			TEXT("set_qpos: missing 'target' field"));
	}
	const bool bByName = By.Equals(TEXT("actor_name"), ESearchCase::IgnoreCase);

	AMjArticulation* Art = nullptr;
	if (bByName)
	{
		Art = Mgr->GetArticulation(Target);
	}
	else
	{
		for (AMjArticulation* A : Mgr->GetAllArticulations())
		{
			if (A && A->ActorId.Equals(Target))
			{
				Art = A;
				break;
			}
		}
	}
	if (!Art)
	{
		return MakeError(TEXT("unknown_articulation"), Target);
	}

	const TArray<TSharedPtr<FJsonValue>>* QPosArr = nullptr;
	if (!Req->TryGetArrayField(TEXT("qpos"), QPosArr) || !QPosArr)
		return MakeError(TEXT("missing_field"), TEXT("set_qpos requires 'qpos' array"));

	struct FJointSlot
	{
		int32 Adr;
		int32 Size;
		int32 Type;
	};
	TArray<FJointSlot> Slots;
	int32 ArtQDim = 0;
	for (UMjJoint* J : Art->GetJoints())