Draw a line that the player follows in 2D (without NavMesh)

Unity Engine
1

Hi folks,

I’ve got a problem and I hope you people can help me. I want to draw a line and after I finished drawing, I want the player to follow it. It’s that simple to explain, but not to program… (for me^^)

My code so far:

GameController.cs:

using UnityEngine;

public class GameController : MonoBehaviour
{
    public LineRenderer LinePrefab;
    PathGameObject pathGameObject;


    private void Awake()
    {
    }

    void Start()
    {

    }

    private void Update()
    {
        if (Input.GetButtonDown("Fire1"))
        {
            // Click, so start drawing a new line.
            pathGameObject = null;
        }
        if (Input.GetButton("Fire1"))
        {
            // Mouse is still down and we are dragging, so keep drawing.
            Draw(Input.mousePosition);
        }
    }

    public void Draw(Vector3 position)
    {
        // Create a plane and see where the mouse click intersects it.
        Plane plane = new Plane(Camera.main.transform.forward * -1, position);
        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        if (plane.Raycast(ray, out float distance))
        {
            if (pathGameObject == null)
            {
                // Starting a new line. Instantiate our "Path Object"
                pathGameObject =
                    UnityEngine.Object.Instantiate(LinePrefab).GetComponent<PathGameObject>();
            }
            else
            {
                // TODO: Check distance between points. This just adds all of them, even
                // if you hold the mouse still.
                Vector3 hitpoint = ray.GetPoint(distance);
                pathGameObject.AddPosition(hitpoint);
            }
        }
    }
}

PathGameObject.cs:

using System.Collections.Generic;
using UnityEngine;

public class PathGameObject : MonoBehaviour
{
    List<Vector3> points = new List<Vector3>();
    LineRenderer lineRenderer;

    void Start()
    {
       
    }

    private void Awake()
    {
        lineRenderer = GetComponent<LineRenderer>();
    }

    void Update()
    {
       
    }

    public Vector2 GetPosition(int index)
    {
        return points[index];
    }

    public void AddPosition(Vector3 position)
    {
        points.Add(position);
        lineRenderer.positionCount = points.Count;
        lineRenderer.SetPositions(points.ToArray());

    }

    public int Count()
    {
        return points.Count;
    }
}

The LinePrefab got the PathGameObject.cs attached and a Line Renderer Component and then I created an empty object in my scene and attached the GameController.cs on it.

What my game does so far is drawing a line and nothing else, because I don’t know how to develop a player following the line.
Can you help me?

Greets,
One

2

There’s a few parts here:

  • the drawing the line (sounds like you have that)

  • the storing of the points in the line in your own data structure (since AFAIK you cannot get those points back from a line renderer after they go in)

  • feed that list of points into a player agent

The final part is identical to a “waypoint following” or “patrol” script, of which there are many.

The general loop will look like this:

SETUP:

  • you’ll have an integer index into the array of points

  • the index will start at zero

UPDATE:

  • the player will walk towards the current point indicated by the index

  • when the player gets “close enough” to that point, the index goes up by one

  • when the index exceeds the count of points, the player stops.

3

Yeah ok… that’s way too hard for me to do this. so I need something else to find… Thanks for your reply.