Physics.IgnoreCollision that does not reset trigger state?

Hi,
In the manual it says:
Physics.Ignore collision is useful, say, for preventing projectiles from colliding with the object that fires them.

I have a problem where I'm using Physics.IgnoreCollision to stop a projectile from hitting its own ship (I can't have every ships projectiles on separate layers as I can have many many factions all shooting at each other)


Problem in the manual it also says: IgnoreCollision will reset the trigger state of affected colliders, so you might receive OnTriggerExit and OnTriggerEnter messages in response to calling this.

So basically everytime a ship fires its guns it leave everyone's perception monitors disappear off radar for a frame (becoming un-selected) etc...

Is there a way to dynamically ignore collision between two rigid-bodies specifically without resetting the trigger state?


Thanks!

 

Whats the process for reporting something that is called out in the manual as part of a feature but is functionally broke?

Turns out when you ignore collision on a child it resets the trigger state on the entire hierarchy. So for example if a bullet ignores collision on a gun and a character holding the gun is standing on a pressure pad, the pressure pad would play its "you left me" and then the "you entered me" sound.

I have a work-arounds but its dirty so our options are:
-Remove all triggers in the game, replace with my own custom math.
-Accept that entities will randomly enter/exit triggers.
-Make anything that interacts with a trigger follow the game objects without being part of the hierarchy. (set position in code)

For now I'm going to create a separate object set its position to the ships position every frame and have it only collide with monitor volumes.

 

Thanks for looking into this!

 

Yant,
Can you post an update if you make progress on this? I'd hate to miss changes in the release notes. I'm currently cutting features from the product, making projectiles triggers as opposed to standard Colliders so I can ignore the damage in OnTrigger. The original intent was to have them be standard Colliders so they would bounce off level geo. Sadly though any work arounds that would allow me to use IgnoreCollision (to avoid having the rigid bodies effect the parents physics) are too buggy for my use case.

Thanks again!

 

Great thanks again!

 

Hi guys,

I currently have the same problem where i change Physics.IgnoreLayerCollision and this causes my OnTriggerExit and OnTriggerEnter to trigger when they shouldn't. I was wondering if anyone came up with a solution or work-around for this?

 

No workaround, you need to not use the system sadly.

I reworked my entire projectile system to user triggers so I could early out in code when the object collided with something it should be ignoring. I then manually apply the rigidbody type force though code when triggers collide, using ray tracing to ensure the correct collision point is calculated as objects with triggers will penetrate into each other. (OnCollision is called when rigid bodies touch but OnTriggerEnter can be called when the triggers are already well inside of each other, thus applying a force will be the wrong location, hence the raycast to determine earliest collision point)

It's messy and took several days to refactor but without a solid delivery date on the fix we had to just not use the Unity physics system for projectile collisions.

 

Heya Yant,
I have not tested In a while. Did you have time to address this so Ignore no longer resets trigger states?

 

FWIW, we are also running into this issue and would be interested in improvements. Either that, or a lot more usable layers.

 

I experience the same problem. For me it's not just a flaw, but a rather critical bug.
I use Physics.IgnoreCollision to temporarily ignore collisions with the terrain so the player can fall through. I can't disable the entire terrain collider, as all other physical objects would fall through then as well.

Can we escalate this somehow?

 

Its a critical bug for me as well. I've rewritten my entire projectile system to work around this issue, but was forced to cut a lot of features out of the system that triggers just don't support.

 

I've also just encountered this. While its not critical for me yet, there is no question that it will bite sooner or later. I'd like to keep updated on this too.

 

Hi Yant,

Is that fix available in the 5.5b yet ? I can not see it in the patch note.

Cheers,
Ceyl

 

Just ran into this myself, couldn't work out for the life of my why my OnTriggerExit was firing, now I know!

Is there an official version number which has the fix?

 

5.5 was just released but I don't see any 'fixed' note on this. Did it come with Physix 3.3?

 

It did. I have not tested the released version but it was fixed in a previous beta!

 

Hi, maybe the ducmentation should be updated too with 5.5 if it's get fixed.

"Note that IgnoreCollision will reset the trigger state of affected colliders, so you might receive OnTriggerExit and OnTriggerEnter messages in response to calling this."

 

Yant,

Can you clarify what got fixed? You just said you agreed with Ceyl's comment:

"Hi, maybe the ducmentation should be updated too with 5.5 if it's get fixed.

"Note that IgnoreCollision will reset the trigger state of affected colliders, so you might receive OnTriggerExit and OnTriggerEnter messages in response to calling this.""

Agreeing with that comment implies that ignore collision still resets the trigger state of colliders??? I thought that was the thing that got fixed...

 

On a separate but related subject, I'm now seeing something I haven't seen before prior to 5.5. When I dynamically add a rigidbody to a gameobject with a collider (the rigidbody is temporarily needed by a temporary fixedJoint.connectedBody), this appears to 'flicker' that collider's enabled state. I'm guessing its the collider's enabled state that 'flickers' because I have numerous other trigger colliders which have their OnTriggerExit() method called, followed immediately by their OnTriggerEnter() method which means they are detecting the disablement of the collider with the new rigidbody followed immediately by detecting its re-enablement.

I'm not sure it is a bug, but it was definitely not there before. My workaround is straightforward - put the temp rigidbody on a temp gameobject as a child of the gameobject with the flickering collider. Walla, the collider no longer flickers.

I'm not going to submit it as a bug, but I believe it is changed behaviour. Yant, are you aware of this?

 

I've submitted it as a bug.

 

So I have got additional question that I could not find in a documentation.

What if I call IgnoreCollision with the same object multiple times. Will the internal list grow or is there a check for duplicates.

What can I do to reset IgnoreCollision for particular Collider. Or remove particular pair from the list.

Is Physics.GetIgnoreCollision including both Layer collision matrix and IgnoreCollision pairs, or just IgnoreCollision. Are other things like IsTrigger included.



And one additional rant. Why Collider has something as useless as Tag property but don't have something so useful as Layer property.

 

Lets just say that I have got a collider that had some IgnoreCollision applied and I don't know what are the other colliders.
How can I reset it's ignore collisions to the starting state.
GetIgnoreCollision unfortunately returns only state of two known colliders.


I'm necroing because it is still semi-relevant question. I don't know why should we create new topic for this.

 

I can make another thread for this issue if you wish, not a problem. Your call.