Temporary disable collision, what's best performance-wise

Hi, Unity 5.5 here.
If I want to prevent a collider from having collisions for a while and then starting having those again,what is better performance-wise between enable/disable collider and change layer to one without collisions?

p.s I’m ignoring activating/deactivating the gameobject as it’s probably the most expansive operation.

Ok so some tests.

First Scenario:

  • 250 GOs with BoxCollider in layer L1
  • 250 GOs with BoxCollider in layer L2
  • 500 GOs with a BoxCollider and a SphereCollider

Changing layer from L1 to L2 and back alternating each frame is the fastest with 0.45 ms of minimum and 0.7ms of maximum.

Enabling/Disabling the colliders on all 500 objects letting them sit in L1 with the other 250 has 1.4 on average when disabling and 1.6 of average when enabling.

Activating/Deactivating all 500 GOs is the slowest with almost 2 ms of average on enable.

Second Scenario:

Same setup per layer but this time one GameObject with 500 BoxColliders and SphereColliders.

Activating/deactivating it has averageof 1.5 ms when deactivating and averageof 2.1 ms when activating.

Enabling and disabling all the colliders is 1,5ms on average when enabling and 1 ms when disabling.

Changing layer is surprisingly good. It stays between 0.3 and 0.4 ms when you group all the colliders in one game object and you switch layer.

Actually, enabling and disabling a GameObject is not a expensive operation at all. If it is just a simple collider, you can just disable and enable it again when needed, if it is a group of colliders, just disable the parent’s GameObject (or their own GameObject, if grouped together in the same GameObject).

You should not assume that some operation is expensive if it is not mentioned in the Scripting API or elsewhere that it actually is. If not sure, you can always use the Profiler to test things out.

if i know right, most performant way is changing “isTrigger” flag, this way, collider does not get affected by physics but remember that they still calculate some trigger events. but i mostly use this technique for disabling collisions just for a while and enable it again.
Don’t Quote on me about this. i am not sure if this is the best way to do this. but from my personal experiences (and profiler results) this is very performant against anything i can think of.
i hope this helps.

please answer this

I have run a test.

I’ve put 250 GOs with boxcollider in layer L1 and the same number in layer L2. If I take 500 brand new GOs with boxcolliders as well, and I switch their layer from L1 to L2 back and forth once alternating layer each frame, I get 0.3 - 0.4 ms of computing time.

If I let those 500 GOs sit in a layer and enable/disable their collider i get from 0.55 to 0.8 ms with spikes sometimes.

If I deactivate the GOs the computing time never goes under 1.1 ms.

So, apparently, chainging layer to a “no collision” layer is the fastes way to obtain the no collision effect in unity 5.5.