Vector3 in if statement

How do I use a Vector3 in an if statement correctly?

I am trying to determine if something is rotated towards a different object, but only on the X and Z rotation. I do not want to look for what the Y rotation is.

Originally I tried -

Code (CSharp):

1. if(transform.eulerAngles == Vector3 (rotateToPosition.eulerAngles.x, y, rotateToPosition.eulerAngles.z))

And it does not work. I know that conventionally a Vector3 looks for something more like (0, 180, 45), but as I am trying to find the Vector, I don't know how to go about writing it. I also do not know how to write that I don't need the Y Vector.

Any help would be appreciated.

 

Still having problems, but it seems that I am looking at this wrong.

I need to be checking if the object is looking towards the x and z positions of another object. I will have to somehow convert the positions to Vectors.

Code (CSharp):

1. if(transform.eulerAngles == Vector3 (rotateToPosition.transform.position.x, rotateToPosition.transform.position.y, rotateToPosition.transform.position.z))

Is not valid.

 

Code (CSharp):

1.         if(transform.rotation.eulerAngles.x == rotateToPosition.transform.rotation.x
2. && transform.rotation.eulerAngles.z == rotateToPosition.transform.rotation.z)
3.  

Is the above valid? No errors are produced by this code, but nothing is being called (I revamped the script earlier, so another issue may be causing nothing being called).

 

You don't use vectors in equality statements.

Vectors are a structure of 2,3, or 4 floats. Floats have an issue with something called 'float error'. This means that even though 2 values may appear to be equal, they're not necessarily equal. It's just the way floats are designed.

Example, you might think 0.1 * 10 equals 1, but it doesn't... it usually comes out as something like 0.99999999999999, or 1.0000000000001. It's because 0.1 in binary is a repeating value, so it gets shaved down.

It's like how in decimal, 1/3 * 3 = 1, but if stored in decimal 0.33333 * 3 = 0.99999

So do NOT compare vectors through equality comparison.




Furthermore, you're comparing euler angles. One euler rotation could be exactly the same as another euler rotation, and have completely different values. Because euler is not a good representation of rotation.

 

You should very rarely compare to vectors to each other directly with ==, on top of that, the eulerAngles will most likely never be equal to the position of another object. Instead, we can calculate the angle between two vectors to figure out if we're facing towards another gameobject.. Hope you were awake during your geometry and vector calculus courses! ...just kidding, Unity can do it for us.

Example:

Code (csharp):

1.  
2. void Update()
3.  {
4.  var other = GameObject.Find("Cube 2").transform.position; // just for my test
5.  var facing = transform.right; // what direction your object is "facing" is not always clear cut
6.  var self = transform.position;
7.  
8.  Debug.DrawLine(self, self+facing*100f, Color.green); //here we scale the facing vector by some amount to make it better visible
9.  Debug.DrawLine(self, other, Color.red);
10.  
11.  // the vector from A to B is equal to B-A
12.  // when calculating angles, we don't care about the magnitude of the vectors, just the direction
13.  
14.  var angleBetween = Vector3.Angle(facing, other-self);
15.  if (angleBetween < 20f)
16.  {
17.  Debug.Log("Pretty close! Angle: " + angleBetween);
18.  }
19.  }
20.