NavMesh名字、层索引、层值之间的转换

    // Nav层名字-->层的值，1、2、4、8、16
    public static int AgentLayerNameToValue(string name)
    {
        int idx = NavMesh.GetNavMeshLayerFromName(name);
        return 0x1 << idx;
    }

    // Nav层名字-->层索引，0、1、2、3、4
    public static int AgentLayerNameToIndex(string name)
    {
        return NavMesh.GetNavMeshLayerFromName(name);
    }

    // 获取角色当前所在的层值，1、2、4、8、16
    public static int GetAgentLayer(NavMeshAgent agent)
    {
        NavMeshHit hit;
        // 不要使用agent.raduis为采样范围，因为当该值为0时，函数将返回0
        bool reach = NavMesh.SamplePosition(agent.transform.position, out hit, 1f, -);
        return hit.mask;
    }

    public static Vector3 SampleNavMeshPosition(Vector3 logicPosition, out bool reachable)
    {
        NavMeshHit hit;
        reachable = NavMesh.SamplePosition(logicPosition, out hit, 1f, -);
        return reachable ? hit.position : logicPosition;
    }

    // 开启导航层
    public static void EnableNavMeshLayer(NavMeshAgent agent, string layerName)
    {
        if (agent == null)
            return;

        int layerValue = NavMesh.GetNavMeshLayerFromName(layerName);
        if (layerValue == -)
            return;

        int mask = agent.walkableMask | 0x1 << layerValue;
        WalkArbiter.SetWalkableMask(agent, mask);
    }

    // 关闭导航层
    public static void DisableNavMeshLayer(NavMeshAgent agent, string layerName)
    {
        if (agent == null)
            return;

        int layerValue = NavMesh.GetNavMeshLayerFromName(layerName);
        if (layerValue == -)
            return;

        int mask = agent.walkableMask & ~(0x1 << layerValue);

        WalkArbiter.SetWalkableMask(agent, mask);
    }

    // 检查某个层是否为开启
    public static bool IsNavMeshLayerOpen(NavMeshAgent agent, string layerName)
    {
        int layerValue = NavMesh.GetNavMeshLayerFromName(layerName);
        if (layerValue == -)
            return true;

        int ret = agent.walkableMask & (0x1 << layerValue);
        return ret >  ? true : false;
    }