Ray not detecting collision when standing ontop of the object? :O

Physics
1

Hi, I’m making a first person game and I came across this weird problem, I’m casting a ray out from the camera to detect what the character is looking at, so I made a block and when the character look at the sides of that block the ray detects it, but when I jump ontop of the block and look down at it the ray no longer detects the block even though the ray goes through it. Why is that?

Here is my code.

RaycastHit hit = new RaycastHit();

void Update () {

		Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);


			if(Physics.Raycast(transform.position, transform.forward, out hit,  raycastDist))
			{
					if(hit.collider.gameObject.CompareTag("Chest"))
					{
				Debug.DrawRay(transform.position, transform.forward * 100,Color.red);
				print ("(E) Open Chest");
				onChest = true;

					}
					else
					{
				Debug.DrawRay(transform.position, transform.forward * 100,Color.red);
						print ("Not hitting anything");
				onChest = false;
					}
			}
	}
2

Simple cast your ray from the position of camera to the direction of it.

Like below:

 Ray ray = new Ray(Camera.main.transform.position, Camera.main.transform.forward);

 

 

            if(Physics.Raycast(transform.position, transform.forward, out hit,  raycastDist))

            {

                    if(hit.collider.gameObject.CompareTag("Chest"))

                    {

                Debug.DrawRay(transform.position, transform.forward * 100,Color.red);

                print ("(E) Open Chest");

                onChest = true;

 

                    }

                    else

                    {

                Debug.DrawRay(transform.position, transform.forward * 100,Color.red);

                        print ("Not hitting anything");

                onChest = false;

                    }

            }
3

You need to set a layer mask on the raycast so it will not hit the player: assign to the player gameobject a custom layer and then set the layerMask parameter to the RayCast.

You can create a layer mask by using

int layermask = 1 << 8; // consider just the layer defined at the index 8 of the layers array

the number 8 is the first of the custom layer. If you are using the predefined IgnoreRaycast layer your code should be:

int layermask = 1 << 2;

If you instead want to collide with everything except a particular layer you have to use:

int layermask = ~(1 << 8); // consider all layer but the one defined at number 8

<< is a binary shift operation while ~ is the negation of that operation. You can combine more layers just using the binary operation on different masks.

4

You’re not using the Ray object you created.

5

Thank you! I forgot about the player itself :stuck_out_tongue:

6

No. That makes no sense, the camera can’t see the player. The reason it is happening is because you are casting a ray from the world position of the player.

Like I said, you are creating a Ray object, but you are not using it in your Physics.RayCast.

7

Yes, it has sense if the capsule collider of the first person shooter will surround the camera !!!

Anyway, your observation is correct, I didn’t notice that he’s not using the ray he has created in the Raycast function.

8

Raycasting from inside a collider won’t return a hit on that collider.

9

Sorry but it will. I had a lot of problems about this before to actually get the point of what was going on.

10

It most certainly does not - read the note here: http://docs.unity3d.com/Documentation/ScriptReference/Physics.Raycast.html

11

A CapsuleCollider is not a SphereCollider… but anyway, I’ll do a little test project and I’ll let you know :wink:
Thanks for pointing me to the unity script reference.

12

I think “sphere” is a misnomer. I’ve achieved the same result with a variety of collider types. However - I believe a CapsuleCast or SphereCast will return its containing collider.

13

I followed Eugenios advice and made the ray not see the player capsule and it worked! :smile: