Simple checpoint system in 3d racing game - some issues.

Questions & Answers
1

Hi

I make 3d racing game and I have some problems with checkpoints system. I found this tutorial Checkpoint and Lap System in Unity Engine - YouTube.

I have problem with using script in my 3d game.
If I play game, unity show following error:

“NullReferenceException: Object reference not set to an instance of an object
checkpoints.OnTriggerEnter (UnityEngine.Collider other) (at Assets/Standard Assets/Scripts/checkpoints.js:14)”

I used scripts: CarCheckpoint.js and Checkpoints.js from tutorial. Files can be download from tutorial Checkpoint and Lap System in Unity Engine - YouTube

Where should I set “3d text”? To Camera or MainCamera?

3

If you are using C# Language. Then here is the C# version of CheckPoint and Laps system.

Laps Script

using UnityEngine;
using System.Collections;

public class Laps : MonoBehaviour {
	
	// These Static Variables are accessed in "checkpoint" Script
	public Transform[] checkPointArray;
	public static Transform[] checkpointA;
	public static int currentCheckpoint = 0; 
	public static int currentLap = 0; 
	public Vector3 startPos;
	public int Lap;
	
	void  Start ()
	{
		startPos = transform.position;
		currentCheckpoint = 0;
		currentLap = 0; 

	}

	void  Update ()
	{
		Lap = currentLap;
		checkpointA = checkPointArray;
	}
	
}

Check Point Script

using UnityEngine;
using System.Collections;

public class checkpoint : MonoBehaviour {
	
	void  Start ()
	{

	}
	
	void  OnTriggerEnter ( Collider other  )
	{
		//Is it the Player who enters the collider?
		if (!other.CompareTag("Player")) 
			return; //If it's not the player dont continue
		

		if (transform == Laps.checkpointA[Laps.currentCheckpoint].transform) 
		{
			//Check so we dont exceed our checkpoint quantity
			if (Laps.currentCheckpoint + 1 < Laps.checkpointA.Length) 
			{
				//Add to currentLap if currentCheckpoint is 0
				if(Laps.currentCheckpoint == 0)
					Laps.currentLap++;
				Laps.currentCheckpoint++;
			} 
			else 
			{
				//If we dont have any Checkpoints left, go back to 0
				Laps.currentCheckpoint = 0;
			}
		}


	}

}

And Just Follow this tutorial to attach scripts on your Game Objects. 1

2

I found where I make mistake. I deleted from code this fragment in checkpoint.js:
//Update the 3dtext
Camera.main.GetComponentInChildren(TextMesh).text = "Checkpoint: “+(CarCheckpoint.currentCheckpoint)+” Lap: "+(CarCheckpoint.currentLap);

and I added this:

function OnGUI () {
GUI.Label (Rect (10, 10, 200, 20), "Checkpoint: “+(CarCheckpoint.currentCheckpoint)+” Lap: "+(CarCheckpoint.currentLap));

}

Sorry for unnecessary question.