Question Why is negative operand not working?

i need the raycast to detect when it hits an object called HEX

this works ok but i need too detect if the ray is not hitting HEX

i am using the negation operand but it is not working

Code (CSharp):

1. if (hit.transform.gameObject.name != "HEX"){
2.  
3.                 Debug.Log("MISS");
4.             }else{
5. Debug.Log"HIT")
6. }

 

The code would work. Try printing the name and see what it actually is that it hits.

 

There's several ways to interpret this:

- test if I'm hitting nothing

- test to make sure that I am hitting things, but make sure they're not named HEX

Your code seems to be doing the latter.

But as Dragon says, print stuff out. You know this already:

You must find a way to get the information you need in order to reason about what the problem is.

What is often happening in these cases is one of the following:

- the code you think is executing is not actually executing at all
- the code is executing far EARLIER or LATER than you think
- the code is executing far LESS OFTEN than you think
- the code is executing far MORE OFTEN than you think
- the code is executing on another GameObject than you think it is
- you're getting an error or warning and you haven't noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling

Debug.Log()

statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

- is this code even running? which parts are running? how often does it run? what order does it run in?
- what are the values of the variables involved? Are they initialized? Are the values reasonable?
- are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as

Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: https://forum.unity.com/threads/how-to-capturing-device-logs-on-ios.529920/ or this answer for Android: https://forum.unity.com/threads/how-to-capturing-device-logs-on-android.528680/

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

When in doubt, print it out!(tm)

Note: the

print()

function is an alias for Debug.Log() provided by the MonoBehaviour class.

 

see i thought the code should work but for some reason it just isnt, it still shows the debug as hit when it hits other objects, i need it to detect when it is not hitting anything like firing at the sky, i thought that would be null but that also does not register,

how would i detect when the ray is not hitting the HEX, say i had a gun and it could only fire if the ray was touching HEX and nothing else, how would i code it to only detect HEX, I THOUGHT THAT WOULD BE =="HEX" but that also still detects when i hit other objects, do you think this is a bug, i am using an older unity 2018 version as i can not upgrade due to some assets in my project that wont upgrade

 

Walk through your code and what you expect values to be when:

- you hit absolutely nothing (hit.transform is likely null, right?)

- you hit something:
---> it is called HEX
---> it is NOT called HEX

You'll see you're not handling all cases correctly if you take it one step at a time.

 

so how do i detect if the ray hits nothing at all? not another object but absolutely nothing

i have tried
if (hit.collider == null)

but it does not work for some reason, it says it should in the unity docs?

 

hit == null


The .collider only exists if the hit happened.

 

just found this

if (!hit)

will give it a go later see if it works

 

god of course, why did i use hit.collider if i want to detect nothing hit, what a fool i am, too much coding time brain corroded thank you

 

Hey, the brain is a delicate organ sometimes needs time to process things.
Balance the yin and yang. Urgency creates frustration. Make sure you are well fed.

 

It can be helpful to explain it to your dog or your houseplant.

"This line here checks the name if I hit nothing..."

or,

"If I hit nothing then I check its name..."

And it will sound wrong.

You can see me explaining a bug to my dog in my avatar picture.

 

Wow, there seems to be a lot misinformation around here ^^. First of all, you should clear up if you talk about Physics, or Physics2D. Those are two seperate physics systems which work different. The normal 3d "Physics" Raycast method returns a bool value indicating if it hit something or not. So accessing anything from the hit structure when the method returns false should already be avoided.

No matter which physics system you're using, the RaycastHit and RaycastHit2D types are structs and therefore can not be compared to null.

This does only work with the RaycastHit2D struct as it implements an implicit conversion operator to bool which internally checks if

hit.collider

is null or not. Physics2D.Raycast works different as it does not return a bool, but directly returns a RaycastHit2D struct. Checking the collider property is the only way to know if you hit something or not, though for 2d they implemented this conversion operator as a shortcut.

Well, this should actually work in both cases (we still don't know if you use 2d or 3d physics. Though if

if(!hit)

works, you're probably using Physics2D?) as the collider property of both structs simply use

Object.FindObjectFromInstanceID

internally by passing the internal colliderID to that method. So the only two possibilities are: the id is invalid and you get null as a result, or if the id is valid, it would return the collider instance.

This:

won't work as hit.transform would return null if you didn't hit anything. So trying to get the gameobject from a null reference would give you a null reference exception.

So it seems a lot wrong conclusions has been drawn here.

 

You’re quite right bunno

if ray out hit

else // I am hit null

 

t

tried it but get error:
error CS0019: Operator `==' cannot be applied to operands of type `UnityEngine.RaycastHit' and `null'

why is this so dificult, all i want to do is detect when the ray hits the object named HEX, i done that

but then i want to do something else when the ray is not hitting HEX, so in other words when the ray is either touching or not touchng anything but HEX, tried so many ways but none seem to work, why can i not use the ! negation operator for this so it means anything other than HEX?


using 3d not 2d

 

Code (CSharp):

1.  
2.              RaycastHit2D hit = Physics2D.Raycast(transform.position, -Vector2.up);
3.                 if (hit == false)
4.                 {
5.                
6.                 }
7.  
8.  

Try this one

looks like Raycast2D's hit is a bool. Raycast3D hit is not a bool and can be checked for null or else.

 

tried t, just gives errors

 

Sorry can't help

 

this is getting ridiculous, how can this be impossible?

all i need is

if ray hit HEX
do this
if ray hits anything else or nothing
do this

but it seems impossible to do

 

can someone from unity explain why this does not work

if(hit.transform.gameObject.name != "HEX"){

Debug.Log("HIT");
}else{
Debug.Log("MISS");

MISS is never called even when the ray is NOT touching the object named HEX

how can i detect when the raycast is NOT touching the gameobject named HEX or anything else? is this really impossible too do in unity?

 

Maybe read the post by @Bunny83 which explained some crucial details you seem to have ignored.

You also need to make sure the objects you're hitting have colliders.

 

the object has a collider, it is detecting hitting the object I NEED TO DETECT WHEN IT IS NOT AS IN NOT HITTING THE OBJECT!!! can you explain why this below will not debug MISS when it is clearly not hitting the object HEX

if(hit.transform.gameObject.name != "HEX"){

Debug.Log("HIT");
}else{
Debug.Log("MISS");

HOW THE F*** CAN THIS NOT BE WORKING IF HEX IS NOT HIT BY THE RAY WHY IS IT NOT CALLING THE MISS DEBUG

 

Calm your tits.

You've given us hardly any context. Only some poorly formatted code followed by basically the same thing over and over that clearly, does, not, work.

If the raycast isn't hitting anything... then there's nothing to check. You need to check that raycast hits something first before you actually check what the raycast may, or may not be hitting.

It's not that hard.

 

Yes, it kinda gets ridiculous Though there's no issue on the Unity side. In your first post you only posted a tiny part of your code. That's why we can't even tell if you're using 2d or 3d physics.

That's what you just posted lately which is a tiny bit more information but you still haven't shown how you do your raycast. Have you actually read the documentation on Physics.Raycast? There is example code which shows how to use it.

As already explained the Physics.Raycast method returns a boolean value indicating if you hit something or not. If you ignore that value and access the "hit" struct anyways, you will run into issues. So the correct way to check that you did hit an object named "HEX" is this

Code (CSharp):

1. if (Physics.Raycast(pos, dir, out hit) && hit.transform.gameObject.name == "HIT")
2. {
3.  
4. }
5.  

You can use an else after that if statement to get the opposite. However if you want directly check the opposite, you just use boolean algebra and it turns into

Code (CSharp):

1. if (!Physics.Raycast(pos, dir, out hit) || hit.transform.gameObject.name != "HIT")
2. {
3.  
4. }
5.  

Note that it's important that those two checks are in the same if statement. You can't do them one after the other because the second condition must only be checked, when the Raycast method returns true. So this if statement would be entered when the raycast returns false (so nothing was hit) or (if we did hit something) when the name of the object we've hit is not "HIT".

Note that hit.transform may return a different transform depending on if the collider you hit belongs to a rigidbody or not. If the collider is part of a compound collider, hit.transform would return the transform of the rigidbody. You can use hit.collider.gameObject if you want to access the gameobject of the actual collider. Though this behaviour can be figured out from the reference source that I linked above.

 

ok the raycast is as bunny has put, which is what i was using but i am using infinity so the ray just goes on and on
then i put:
if(hit.transform.gameObject.name != "HEX"){

Debug.Log("HIT");
}else{
Debug.Log("MISS");

now the debug MISS is called when the ray hits another object not called HEX, ok so thats working but how do i detect when the ray is not hitting an object at all, as in not hitting anything so like this

if(hit.transform.gameObject.name != "HEX"){

Debug.Log("HIT"); // hitting object named HEX
}else{
Debug.Log("MISS"); // hitting object not named HEX

NOW I NEED AFTER THAT

}else{
Do something here when not hitting any objects?

might be easier if i put it like this

my player has an auto gun that can only be fired when ONLY the object called HEX is in line of the raycast, NOT ANYOTHER OBJECT...how would i detect that the object is not in line so it cannot be fired

 

Iunno... maybe...

Code (CSharp):

1. if (//raycast)
2. {
3.     //we hit something
4. }
5. else
6. {
7.     //nothing was hit
8. }

???

 

I can't stand it any longer.

The critical logic we have been spinning about begins on line 48.

Code (csharp):

1. using UnityEngine;
2.  
3. // @kurtdekker - for @melonhead in the thread:
4. // https://forum.unity.com/threads/why-is-negative-operand-not-working.1340582
5. //
6. // To use:
7. //    - make a scene with camera / light (default)
8. //    - drop ONE copy of this script on ONE of the above GameObjects (doesn't matter which)
9. //    - press PLAY
10. //    - use left/right arrows to move the box, your "downward casting cursor"
11. //    - read the spew in the Debug.Log() console window
12. //
13. // Watch the scene closely as this runs.
14. //
15. // You can hit:
16. //    - nothing
17. //    - something called HEX
18. //    - other things NOT called HEX
19.  
20. public class ForMelonHead : MonoBehaviour
21. {
22.     GameObject box;
23.  
24.     private void Start()
25.     {
26.         // this is our marker or cursor; we will cast DOWN from it
27.         box = GameObject.CreatePrimitive(PrimitiveType.Cube);
28.  
29.         // left ball
30.         var sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);
31.         sphere.transform.position = new Vector3(-1, -2);
32.  
33.         // right ball - named HEX
34.         sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);
35.         sphere.transform.position = new Vector3(+1, -2);
36.         sphere.name = "HEX";
37.     }
38.  
39.     private void Update()
40.     {
41.         // input
42.         float xm = Input.GetAxisRaw("Horizontal");
43.  
44.         // move
45.         box.transform.position += Vector3.right * (3 * xm * Time.deltaTime);
46.  
47.         // raycast
48.         Ray ray = new Ray(origin: box.transform.position, direction: Vector3.down);
49.         RaycastHit hit;
50.         if (Physics.Raycast(ray: ray, hitInfo: out hit))
51.         {
52.             if (hit.collider.name == "HEX")
53.             {
54.                 Debug.Log("Hitting a thing called HEX!");
55.             }
56.             else
57.             {
58.                 Debug.Log("Hitting SOMETHING, but its name is NOT HEX");
59.             }
60.         }
61.         else
62.         {
63.             Debug.Log("Hitting absolutely NOTHING");
64.         }
65.     }
66. }

 

was a problem with the unity install for some reason, i reinstalled everything and is now the same script is working as it should, not sure what the problem was, looks like some sort of gremlin got into the unity install, thanks for all the above help, might use some of it as looks a bit more eficient than my original code is.

regards

 

A gremlin?

 

gremlin = bug, or similar!

 

Lol yeah right.

 

Even though totally off topic: a gremlin
Some may know the movie Gremlins by Steven Spielberg.

That said, in the last 10+ years I never had any issues that has been solved by reinstalling Unity, unless I actually, literally messed something up in the installation itself which can't really happen by accident. Especially the issue like the one mentioned in this thread is extremely unlikely to be fixed by reinstalling.

 

Thanks guys I know what a gremlin was I was just, confirming that he actually meant a gremlin.

Gremlin was coined in world war 2, used to explain defective machinery. Gremlin image of a furry creature similar to a raccoon or a mongoose was used in American pro war propaganda. Particularly it was used to encourage women to aid in the war effort and the preservation of foods. Keep the gremlins away from the food buy canned spam.

One issue I had with unity that was solved by a reinstall was a fault with unity hub unable to recognize the location of a unity editor version on my HDD.