[SOLVED]Test If the (NavMesh)Agent Has Arrived At The Targeted Location

Hi,

... is it possible to test if the agent has arrived at the location(target)?I didn't find anything about it...
Here' s a short picture, to explain my problem a bit more:

 

I suggest looking at the docs a little harder. Its all there.

 

Yes, I know.It's 'pathStatus', right?But there's no example how to use it.There isn't also a video about it.

 

http://bit.ly/1FyKVdf

 

Here are some problems that appear(due Unity 4 and Unity 5?):

error CS0120: An object reference is required to access non-static member `UnityEngine.NavMeshAgent.pathPending'
error CS0120: An object reference is required to access non-static member `UnityEngine.NavMeshAgent.remainingDistance'
error CS0120: An object reference is required to access non-static member `UnityEngine.NavMeshAgent.hasPath'

And please, don't use this 'LetMeGoogleThatForYou'-S*** anymore. Thanks!

 

I've already got it!

 

What was the solution for this? I am building a Behavior Tree and using a MoveTo Task for debugging.

1. I set destination.
2. If pathPending then return RUNNING
3. If !pathPending && hasPath then return RUNNING

I still need the following return states...
4. If invalid destination (off mesh or unreachable) return FAILED
5. If Agent tried and failed to reach destination return FAILED
6. If Agent successfully reaches destination return SUCCESS

I don't see anything in the documentation to test for case 4,5, and 6

 

4. To check whether or not the target is unreachable...

Code (CSharp):

1. // navpath: The NavMeshPath
2.  
3. if (navpath.status == NavMeshPathStatus.PathInvalid || navpath.status == NavMeshPathStatus.PathPartial) {
4.    // Target is unreachable
5. }

5. This is pretty much covered by No. 4

6. To check if the agent has reached the target...

Code (CSharp):

1. // agent: Agent's transform component
2. // nav: Agent's NavMeshAgent component
3. // target: Target's transform component
4.  
5. if (Vector3.Distance (agent.position, target.position) <= nav.stoppingDistance) {
6.     // Target reached
7. }

 

Thats the solution:

Code (csharp):

1.  if(!youragent.pathPending) {
2.  if(youragent.remainingDistance <= youragent.stoppingDistance) {
3.    if(!youragent.hasPath | | youragent.velocity.sqrMagnitude == 0f) {
4.       //...
5.    }
6.  }
7. }

 

5. Track remainingDistance value, if it doesn't change, your navigator is stuck for some reason... most likely because 5.
6. Same as 5, but the value is within a target distance threshold (decided on by you)

When I was dealing with moving my things around, I would have a tolerance for arriving at a point.. if I got within a certain small distance, I would consider that successful arrival, and the agent would then move on to next action.

 

Because google results...

For anyone finding this in 2017, NavMashAgent.path.status includes 4, 5, & 6. I noticed 6 was not included in this thread.

1. NavMeshAgent.SetDestination(Vector3)
2. NavMeshAgent.pathPending
3. NavMeshAgent.hasPath
4. NavMeshAgent.path.status == NavMeshPathStatus.PathInvalid //If invalid destination (off mesh or unreachable) return FAILED
5. NavMeshAgent.path.status == NavMeshPathStatus.PathPartial //If Agent tried and failed to reach destination return FAILED
6. NavMeshAgent.path.status == NavMeshPathStatus.PathComplete //If Agent successfully reaches destination return SUCCESS

 

Wow!!! you can't escape nerdy intellectualism even at Unity. Doesn't suprise me!

 

Well I'm not unity staff, just a glorified spam cleaner and apparently annoying person. Do you have a navmesh related issue?

 

This is a very helpful thread. Thank you!

 

Why this does't work with me ?

 

And this doe'st work too for my...

 

I know this is a huge necro but it's still one of the first google search results, so I wanted to comment on this.
This code example worked in almost all cases, but there is one specific case that did not work for me.

When the agent can't find a valid path (for example if you set a value that is outside of the nav mesh or if it is blocked) then in some cases pathPending will still be true while hasPath is also true with the pathStatus being != PathComplete, so basically the agent detected an invalid path and will try (forever?) to find an other valid path.

To avoid this I added a else condition
if agent.pathPending && agent.hasPath && agent.pathStatus != NavMeshPathStatus.PathComplete
in this case I assume that the agent will not find any other valid path and cancel my agent.

This is a very specific / rare case, so most user will not notice it, but maybe this helps someone.

 

I dont understand why Unity team didnt think to raise an event when path ended execution with some status as parameter. This is so simple.

 

I don't think it's simple. But you can query it all kinds of way for your game. The reason it's not simple is because arrived means very different things in a zombie game than it does in an adventure game with no forces acting on an agent.

 

I think that if in the previous frame the agent

hasPath

, and in the current frame it does not

hasPath

, then it is considered to have reached it's current destination.
Some sort of event could easily be thrown when the bool is flipped so you don't need to check it every frame nor keep track of the previous frame state, but I guess that's just how life goes.

 

This really should be changed to be event based, just as the new input system did change it to.

pseudo code:

Code (CSharp):

1. navMeshAgent.OnDestinationReached += YourMethod;

 

This is nonsense cuz Google send me here. Nice job.

 

My solution is, it is freaking convoluted, i dont fully understand it myself anymore, but works somehow: ( the solution i wrote above would how it should be not how it is)

Code (CSharp):

1.    private bool CheckForDestinationReached(float startTime)
2.     {
3.         return Time.time - startTime > 1f && agent.pathStatus == NavMeshPathStatus.PathComplete &&
4.                agent.remainingDistance <= agent.stoppingDistance;
5.     }

 

@Unity_AndyP I know you might not be the right person to fix that but maybe you can forward it to someone at unity to get this to a nicer solution

 

Its nothing to fix but to read the docs and interpret the AI movement you wish to have.
I mean if you dont know how to do it properly, then just watch a youtube video where people explain it. Its not that hard

 

i completly abandoned using navagent. it has more bugs the more you work with it. for example avoidance and imposible to add navmesh obstacle on top of agent =D
Instead i am using static method of navmesh to calculate path and CharacterController to move

 

Unity is all about making it easy to understand and removing complexity. So I disagree with your opnion.
Complexity can be hidden behind easy to understand Methods that do exactly what you exepct of them.

 

I use it because I still love to take everythign unity gives us. And it works its just not beautiful in its current form..

 

i can share code from my system if you will have desire to use something else. in my version units not able to push each other. and you can body block unit. its part of mechanic that is in my game.

Code (CSharp):

1.    public static bool CalculatePath(this NavMeshPath navMeshPath, Vector3 start, Vector3 end, int mask, out float lenSqr)
2.   {
3.     lenSqr = 0f;
4.     if (NavMesh.CalculatePath(start, end, mask, navMeshPath) && navMeshPath.corners.Length > 1 && navMeshPath.status == NavMeshPathStatus.PathComplete)
5.     {
6.       for (int i = 1; i < navMeshPath.corners.Length; i++)
7.       {
8.         lenSqr += (navMeshPath.corners[i - 1] - navMeshPath.corners[i]).sqrMagnitude;
9.       }
10.     }
11. //lenSqr is path length to power of 2. 0.5f is minimal path length
12.     return lenSqr > 0.5f;
13.   }
14.  

and you also have to ensure that start and end vector3 values are on navmesh. The way i do it is
NavMesh.SamplePosition(start, out NavMeshHit startPositionHit, 10f, NavMesh.AllAreas) && NavMesh.SamplePosition(end, out NavMeshHit endPositionHit, 10f, NavMesh.AllAreas)

Using this path you can move character controller and add navmesh obstacle to it and it will still work. Consider that corner[0] is start position so you have to move to corner[1] right away

 

Thanks thanks my code works for us aswell ( just dont forget that code can be beautiful and easy too @Unity)

 

Truth is most people do not help others here out "the kindness of their hearts", but for the "holier-than-thou" attitude and kick they get from belittling someone asking for help. In most cases it would be suffice to say "You could look here and it would help", but that doesn't bring the same thrill and dopamine rush as an uppity post does.

 

for anyone still following up on this thread, the simple and final solution is simply to check the distance and compare it to a desired value for what you considered as 'reached'. If you want, you can use the navmesh's own properties for that:

Code (CSharp):

1. if (_agent.remainingDistance <= _agent.stoppingDistance) {
2.     // reached
3. }

or just sample the distance yourself with your own algorithm and compare it with your custom stopping distance:

Code (CSharp):

1. if (CalculateDistance() <= CalculateStopingDistance()) {
2.     // reached
3. }

and of course you could turn it into an event-based structure, but I highly recommend you not to go down that path, since navmesh is usually used in state machine patterns, and that means you'd need to take the current state in mind in every event, and that can turn very messy very fast. you can just stick to checking the condition once every few frames and call it a day.
thanks for reading.