How To Add Creature Navigation with Navigation Mesh

Navigation Mesh allows characters (known as Agents) to navigate the AR scene using point-and-click touch inputs.

Prerequisites

You will need a Unity project with Lightship AR and Lightship Meshing enabled. For more information, see Installing ARDK 3.0 and How to Create a Mesh and Add Physics.

Adding the Navigation Mesh Manager

To add a LightshipNavMeshManager:

1. Create an empty GameObject.
   1. In the Hierarchy, select the root of the scene.
   2. From the main menu, select GameObject, then Create Empty Child.
   3. Name it LightshipNavMeshManager.
2. Add a LightshipNavMeshManager component to the empty GameObject.
   1. In the Inspector window, click Add Component.
   2. Type "LightshipNavMeshManager" in the search window, then select it.
3. If you want to see the LightshipNavMesh, add a LightshipNavMeshRenderer component to the GameObject as well. This will render the LightshipNavMesh on-screen when the camera moves.
   1. In the Inspector window, click Add Component again.
   2. This time, search for "LightshipNavMeshRenderer" instead, then select it.

You can also add the LightshipNavMeshManager prefab from the NavMesh sample project. For more information, see Sample Projects.

Adding an Agent to the LightshipNavMesh

To test out the LightshipNavMesh, we need to add an Agent to the scene to traverse it. The NavMesh sample project contains an Agent prefab that you can use for testing, but you may wish to create your own instead.

To create an Agent prefab:

1. Add an object to the scene to act as an Agent.
   1. In the Hierarchy, select the root of the scene.
   2. Right-click, then select Create. For this example, choose Cube to add a basic cube as the testing Agent. Name it TestAgent.
2. Add a LightshipNavMeshAgent component to the new Agent.
   1. In the Hierarchy, select TestAgent.
   2. In the Inspector window, click Add Component. Search for "LightshipNavMeshAgent", then select it to add the component.
3. Add a LightshipNavMeshAgentPathRenderer component to show the path the Agent can take in the scene.
   1. In the Hierarchy, select TestAgent.
   2. In the Inspector window, click Add Component, then search for "LightshipNavMeshAgentPathRenderer" and select it to add the component.
4. Drag the Agent to the Assets window to make a prefab, then remove it from the scene.

Create a Script to Control the Agent

To add a control script to the Agent:

1. Add a script Asset.
   1. In the Assets window, right-click, then select Create, then C# Script.
   2. Name the new script NavMeshHowTo.
2. Attach the script to the Agent.
   1. Select your Agent prefab, then click "Add Component" in the Inspector window.
   2. Search for "NavMeshHowTo", then select it to add the controller script to the prefab.
3. Open NavMeshHowTo.cs, then copy in this sample script:

Click here to show the NavMeshHowTo script!

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using Niantic.Lightship.AR.NavigationMesh;
using UnityEngine.InputSystem;

/// SUMMARY:
/// LightshipNavMeshSample
/// This sample shows how to use LightshipNavMesh to add user driven point and click navigation.
/// When you first touch the screen, it will place your agent prefab.
/// Tapping a location moves the agent to that location.
/// The toggle button shows/hides the navigation mesh and path.
/// It assumes the _agentPrefab has LightshipNavMeshAgent on it.
/// If you have written your own agent type, either swap yours in or inherit from it.
///
public class NavMeshHowTo : MonoBehaviour
{
    [SerializeField]
    private Camera _camera;

    [SerializeField]
    private LightshipNavMeshManager _navmeshManager;

    [SerializeField]
    private GameObject _agentPrefab;

    private GameObject _creature;
    private LightshipNavMeshAgent _agent;

    void Update()
    {
        HandleTouch();
    }

    public void ToggleVisualisation()
    {
        //turn off the rendering for the navmesh
        _navmeshManager.GetComponent<LightshipNavMeshRenderer>().enabled =
            !_navmeshManager.GetComponent<LightshipNavMeshRenderer>().enabled;

        //turn off the path rendering on any agent
        _agent.GetComponent<LightshipNavMeshAgentPathRenderer>().enabled =
            !_agent.GetComponent<LightshipNavMeshAgentPathRenderer>().enabled;
    }

    private void HandleTouch()
    {
        //in the editor we want to use mouse clicks, on phones we want touches.
        #if UNITY_EDITOR
        if (Input.GetMouseButtonDown(0) || Input.GetMouseButtonDown(1) || Input.GetMouseButtonDown(2))
        #else
        //if there is a touch, call our function
        if (Input.touchCount <= 0)
            return;

        var touch = Input.GetTouch(0);

        //if there is no touch or touch selects UI element
        if (Input.touchCount <= 0 )
            return;
        if (touch.phase == UnityEngine.TouchPhase.Began)
        #endif
        {
            #if UNITY_EDITOR
            Ray ray = _camera.ScreenPointToRay(Input.mousePosition);
            #else
            Ray ray = _camera.ScreenPointToRay(touch.position);
            #endif
            //project the touch point from screen space into 3d and pass that to your agent as a destination
            RaycastHit hit;
            if (Physics.Raycast(ray, out hit))
            {
                if (_creature == null )
                {
                    _creature = Instantiate(_agentPrefab);
                    _creature.transform.position = hit.point;
                    _agent = _creature.GetComponent<LightshipNavMeshAgent>();
                }
                else
                {
                    _agent.SetDestination(hit.point);
                }
            }
        }
    }
}