Nav: Add NavStop component

Hi @reeseschultz ,

I tweeted you just the other day regarding issues I’m having stopping an agent. Thought I’d start a discussion on here as it will be easier! So, in my project, I’m creating a couple of different component data structs to handle agent actions. For example:

public struct NavGoTo : IComponentData
{
     public float3 Location;
}

public struct NavStop : IComponentData
{
     // nothing here
}

public struct NavWander : IComponentData
{
     // nothing here
}

Then in my movement system I have

     // Handle NavWander
            Entities
                .WithAll<NavWander>()
                .WithNone<NavHasProblem, NavNeedsDestination, NavStop>()
                .WithReadOnly(renderBoundsFromEntity)
                .WithNativeDisableParallelForRestriction(randomArray)
                .ForEach((Entity entity, int entityInQueryIndex, int nativeThreadIndex, in Parent surface) =>
                {
                    if (
                        surface.Value.Equals(Entity.Null)
                    ) return;

                    var random = randomArray[nativeThreadIndex];
                    commandBuffer.AddComponent(entityInQueryIndex, entity, new NavNeedsDestination
                    {
                        Destination = NavTools.GetRandomPointInBounds(
                            ref random,
                            renderBoundsFromEntity[surface.Value].Value
                        )
                    });

                    randomArray[nativeThreadIndex] = random;
                })
                .WithName("NavWanderSystem")
                .ScheduleParallel();

            ... 
            
            // Handle NavStop 
            Entities
                .WithNone<NavHasProblem, NavWander>()
                .WithReadOnly(translationFromEntity)
                .WithNativeDisableParallelForRestriction(translationFromEntity)
                .ForEach((Entity entity, int entityInQueryIndex, in NavStop navStop) =>
                {
                    commandBuffer.RemoveComponent<NavStop>(entityInQueryIndex, entity);
                    commandBuffer.AddComponent(entityInQueryIndex, entity, new NavNeedsDestination
                    {
                        Destination = translationFromEntity[entity].Value
                    });
                    Debug.Log($"Stop entity ${entity.Index}");
                }).WithoutBurst()
                .WithName("NavStopSystem")
                .ScheduleParallel();

            Barrier.AddJobHandleForProducer(Dependency);

Ok, so this works - sometimes! Everytime I add a NavStop the system correctly picks this up and I see the DebugLog. However, the agent doesn’t always stop. I’ve tried quite a few different things (been at this simple stop functionality for about 4 days! lol) and while I’m new to ECS, I can’t for the life of me figure out why what I’m doing shouldn’t work… the fact it sometimes works makes it even more frustrating. I’m wondering if it could be something to do with the way NavNeedsDestination works and so my next step was to ask you for some advice. Can you think of any reason why setting the Destination to the entities Translation won’t work?

Just to note, I’ve also used the Translation in the ForEach lambda rather using var translationFromEntity = GetComponentDataFromEntity<Translation>(true); but get the same result.

Any thoughts? Would really appreciate any insight you might have.

Thanks

Edit: Maybe it’s because I’m using .ScheduleParallel() and they are conflicting? It appears as though .Schedule improves things slightly but there is still and issue.

[reeseschultz]

@P-Stringer I added NavStop, which is part of Nav v0.15.0. You can view the changes in this commit. It should work. I tested it in the NavHybridDemo by making the agent stop when Tab is pressed (sometimes the agent’s animation freezes—that’s a separate, scene-specific issue). Anyway, I really appreciate that you brought this up, and also that you tried to apply a workaround and shared the code for what you did (most people don’t). I was able to knock this out this morning since I don’t have much time later today.

Be aware that the feat/demo-overhaul has not been synced with master, meaning it’s missing later changes that that were added to master. Like I said, I’ll try to sync them, but it’ll be at least a week before I can do that. There’s no NavFollow component in that branch (yet!), but the underlying code should now be ready to support it, is what I mean. I know it should be about ready because the new “Stranded” demo supports click-and-drag movement.

[reeseschultz]

Glad it helps!