Click Navigation Project

Unity Version: 2019.3

Build

Setup

Import Ethan

Unity Standard Assets to get similar assets to the ones in the book.

Uncheck everything when importing, then check the box for Standard Assets > Characters > ThirdPersonCharacter. This will take up less space in your project view.

You can find a model called Ethan.fbx at Standard Assets > Characters > Models > Ethan.fbx. You can find the animation clips at Standard Assets > Characters > Animation. You can find the materials at Standard Assets > Characters > Materials

Step 1: Initialize Environment

• Floor and Obstacles
• Lighting

1. Add a floor plane
2. Add an obstacle cube
3. Prefab and name both
4. Give obstacle a color
5. Create an Empty called Environment in Hierarchy
6. Parent both to environment

Step 2: Set Grid Snapping Settings

At Edit > Grid and Snap

1. Set Grid Size to 1
2. Set Move to 1
3. Set Scale to 1
4. Set Rotate to 90

Step 3: Create a Maze

Use the move, scale, and rotate tools to create a maze with the obstacle instances.

Step 4: Add Ethan

1. Add the Ethan model to the maze.
2. Change the material on EthanBody to EthanGrey
3. Scale the environment up to (2,2,2)

Step 5: Add NavMeshAgent

1. Add NavMeshAgent to Ethan
2. Select all environment objects and set Navigation > Object > Navigation Static to true.
3. Select all obstacles and set Navigation Area to "Not Walkable"
4. Open Navigation window and Bake
5. Tweak Agent Radius to define NavMesh area

Step 6: Follow Target

1. Add a Sphere called "Target"
2. Give the Target a material that contrasts Obstacle
3. Add a script to Ethan called Movement.cs

using UnityEngine;
using UnityEngine.AI; // Need this for NavMeshAgent

public class Movement : MonoBehaviour
{
    [SerializeField] Transform target; // Get transform of Target
    NavMeshAgent navMeshAgent; // NavMeshAgent Component
    void Awake() // We can use awake to grab references before Start()
    {
        // Get reference to NavMeshAgent
        navMeshAgent = GetComponent<NavMeshAgent>();
    }

    void Update()
    {
        // Every frame update the destination to current target position
        navMeshAgent.destination = target.position;
    }
}

4. Attach Target to Movement.cs on Ethan
5. Press Play

Step 7: Animation

1. Turn off Apply Root Motion on Ethan's Animator
2. Create a new Animator Controller named Movement and attach it to Ethan
3. Add a new animator parameter called "Speed" of type float
4. Create a new 1D Blend Tree called Move in the Animator. Make it dependent on the Speed parameter.
5. Add three motions: HumanoidIdle, HumanoidWalk, HumanoidRun
6. Uncheck Automate Thresholds in blend tree
7. Use Compute Thresholds > Velocity Z to calculate the thresholds based on animation forward velocity.
8. Set Ethan > NavMeshAgent > Speed to the highest threshhold value. (5.66 w/ HumanoidRun)
9. In Movement.cs set the Speed parameter of the animator as the z velocity of the player.

using UnityEngine;
using UnityEngine.AI;

public class Movement : MonoBehaviour
{
    [SerializeField] Transform target; 
    NavMeshAgent navMeshAgent; 
    Animator animator; // Declare animator as private property
    void Awake()
    {
        navMeshAgent = GetComponent<NavMeshAgent>();
        animator = GetComponent<Animator>(); // Get reference to animator
    }

    void Update()
    {
        navMeshAgent.destination = target.position;
        UpdateAnimator();
    }

    void UpdateAnimator() {
        // Get the velocity of the NavMeshAgent
        Vector3 velocity = navMeshAgent.velocity;

        // Convert the velocity from global to local.
        Vector3 localVelocity = transform.InverseTransformDirection(velocity);

        // Speed is a scalar. We can get it from the z axis of the local velocity. 
        float forwardSpeed = localVelocity.z;

        // Now we can set the Speed parameter of the Animator.
        animator.SetFloat("Speed", forwardSpeed);
    }
}

Additionally, Ethan will always follow the Target even if it moves.

Step 8: Click To Move

1. Create a new script called "Control.cs" and attach it to the main camera.
2. Write code that raycasts from the mouse position ont he screen and sets the position of the target to the point where the ray hit.

using UnityEngine;

public class Control : MonoBehaviour
{
    [SerializeField] Transform target;
    Camera camera;
    void Awake()
    {
        // Get a reference to the Camera component.
        camera = GetComponent<Camera>();
    }

    void Update()
    {
        // Get the point on the screen where the mouse is.
        Vector2 mousePosition = Input.mousePosition;

        // Initialize a ray using the ScreenPointToRay method.
        Ray cameraRay = camera.ScreenPointToRay(mousePosition);

        // Declare a RaycastHit
        RaycastHit hit;
        
        // Start a raycast and pass in the RaycastHit to get data back.
        bool hitSomething = Physics.Raycast(cameraRay, out hit);

        // If the ray did not hit anything, end the function.
        if (!hitSomething) return;

        // Set the position of the target to the point where the ray hit.
        target.position = hit.point;
    }
}

Now the target moves in response to the mouse position, but it moves to any point hit by the ray, including itself. This is problematic and not fun.

Trainer Note: Ask the students to explain why this is happening. It may uncover some gaps in knowledge that should be addressed.

3. Add a new tag to the floor called "Ground".
4. Edit the Control.cs script to check if the ray hit an object with the tag "Ground".

void Update()
{
    Vector2 mousePosition = Input.mousePosition;
    Ray cameraRay = camera.ScreenPointToRay(mousePosition);
    RaycastHit hit;
    bool hitSomething = Physics.Raycast(cameraRay, out hit);
    if (!hitSomething) return;

    // If we didn't hit the ground, end the function
    if (!hit.collider.CompareTag("Ground")) return;

    target.position = hit.point;
}

5. Edit the Control.cs script so that the Target only moves when the mouse is clicked.

void Update()
{
    // If the left mouse button was NOT clicked on this frame, end the function.
    if (!Input.GetMouseButton(0)) return; 

    Vector2 mousePosition = Input.mousePosition;
    Ray cameraRay = camera.ScreenPointToRay(mousePosition);
    RaycastHit hit;
    bool hitSomething = Physics.Raycast(cameraRay, out hit);
    if (!hitSomething) return;
    if (!hit.collider.CompareTag("Ground")) return;
    target.position = hit.point;
}

Step 9: Polish

1. Change skybox to solid color
2. Set camera projection to "orthographic"
3. Adjust camera size and position

Resources

Grid Snapping Set Grid Size to 1 and Increment Settings > Move to 1