3 Raycasts, 1 Object

Unity Engine
1

Hi forum,

I was playing with code for my upcoming game and decided to cast multiple rays in one function. But I stumbled upon the problem that sometimes rays generate such error:

NullReferenceException: Object reference not set to an instance of an object

Does anyone could tell what is the possible reason for that. My method code is:

	public void DeathCollision()
	{
		Vector3 frntCol = transform.TransformDirection(Vector3.right);
        RaycastHit hit;
		RaycastHit hitTop;
		RaycastHit hitBot;

        Debug.DrawRay(transform.position, frntCol * 1, Color.green, 5);
		Debug.DrawRay(transform.position + new Vector3(0, transform.localScale.y/2f, 0), frntCol * 1, Color.red, 5);
		Debug.DrawRay(transform.position + new Vector3(0, -transform.localScale.y/2f, 0), frntCol * 1, Color.blue, 5);
		
		bool midRay = Physics.Raycast(transform.position, frntCol, out hit, 1.0f);
		bool topRay = Physics.Raycast(transform.position + new Vector3(0, transform.localScale.y/2f, 0), frntCol, out hitTop, 1.0f);
		bool botRay = Physics.Raycast(transform.position + new Vector3(0, -transform.localScale.y/2f, 0), frntCol, out hitBot, 1.0f);

        if (midRay || topRay || botRay)
        {
           //Error happens here in this conditional statement. I presume that hit is not being populated for some reason
            if(	hit.transform.gameObject.layer == 8 ||
				hitTop.transform.gameObject.layer == 8 ||
				hitBot.transform.gameObject.layer == 8)
            {
                Debug.Log("DeathCollision");

                transform.Translate(Vector3.right * 1.0f);
                transform.Translate(Vector3.up * 2.0f);
                rigidbody.velocity = Vector3.zero;
            }
			else
			{
				Debug.Log ("Acceleration");
				
				transform.Translate(Vector3.right * 1.0f);
                transform.Translate(Vector3.up * 2.0f);
			}
        }
	}

(P.S when I have only one raycast everything works with no problems)

2

I don’t have Unity with me, but I suspect…

if (midRay || topRay || botRay)

This will return true if only one of the rays hits. So let’s assume that midRay hits but top and bot Rays do not.

Then in this line…

if( hit.transform.gameObject.layer == 8 ||

                hitTop.transform.gameObject.layer == 8 ||

                hitBot.transform.gameObject.layer == 8)

hitTop and hitBot would not be assigned to anything, because the ray didn’t hit. If you plan only checking all of them, you should do

midray  topRay  botRay

Erik

3

Thanks for the reply.

I am not planning to check if they were all hit at the same time. The idea is to check if one of them was hit or not, that is why I am using logical operator || (logical or). In other words, to satisfy my condition only one of these Raycasts should hit something.

Any more thoughts maybe? :face_with_spiral_eyes:

4

But that is the reason it does not work
only one of the rays hit → only one of the RaycastHits exists, but you still try to operate with them (they are null)

5

Ok it makes sense now… So what would be the alternative approach then? :slight_smile:

6

How about this?

        public void DeathCollision()
        {
//Move these 3 raycasts
            //bool midRay = Physics.Raycast(transform.position, frntCol, out hit, 1.0f);
            //bool topRay = Physics.Raycast(transform.position + new Vector3(0, transform.localScale.y/2f, 0), frntCol, out hitTop, 1.0f);
            //bool botRay = Physics.Raycast(transform.position + new Vector3(0, -transform.localScale.y/2f, 0), frntCol, out hitBot, 1.0f);
//into this if test, but all using the same raycastHit parameter
            if (Physics.Raycast(transform.position, frntCol, out hit, 1.0f) ||
Physics.Raycast(transform.position + new Vector3(0, transform.localScale.y/2f, 0), frntCol, out hit, 1.0f) ||
Physics.Raycast(transform.position + new Vector3(0, -transform.localScale.y/2f, 0), frntCol, out hit, 1.0f) )
            {
//Because the if test uses ORs, it stops performing them once one returns true,
//and the single hit param will contain the information from that ra
                if( hit.transform.gameObject.layer == 8){
//then these other hit's are not needed
                    //hitTop.transform.gameObject.layer == 8 ||
                    //hitBot.transform.gameObject.layer == 8)
...snip
7

Well that looks nice… Thanks, I will try it :slight_smile: