【Unity】問題記錄"SetDestination" can only be called on an active agent that has been placed on a NavMesh

問題："SetDestination" can only be called on an active agent that has been placed on a NavMesh.

原因：導航NavMeshAgent組件所在物體距離Navmesh導航網格太遠，'NavMeshAgent.SetDestination'設置導航目標點失敗

解決：在設置導航目標點之前，可以用‘ NavMeshAgent.isOnNavMesh’判斷，在返回值爲Ture後再'NavMeshAgent.SetDestination'，如果返回值爲False，說明當前NavMeshAgent不在導航網格上，可用‘NavMeshAgent.Warp’糾正位置。

此外，還可以用‘NavMesh.SamplePosition’檢測地圖內某點是否在導航網格NavMesh內

    public bool TestNavigation()
    {
        if (navMeshAgent.isOnNavMesh)
        {
            NavMeshHit navigationHit;
            if (NavMesh.SamplePosition(targetPosition, out navigationHit, 15, navMeshAgent.areaMask))
                return navMeshAgent.SetDestination(navigationHit.position);
            return false;
        }
        else
        {
            return navMeshAgent.Warp(warpPosition);
        }
    }