Using Physics2D.OverlapCircleNonAlloc keeep causing GC Allocations.

Unity Engine
,
1

I am using this code:

private void CheckGrounded()
    {
        Collider2D[] result = new Collider2D[10];

        bool touchGround = false;

        if (Physics2D.OverlapCircleNonAlloc(playerTransform.localPosition, phisicsSettings.checkRadius, result) > 0)
        {
            for (int i = 0; i < result.Length; i++)
            {
                try
                {
                    if (result[i].gameObject.layer == phisicsSettings.platformLayer)
                    {
                        if (!isGrounded)
                        {
                            TouchGroundAnimation();
                        }

                        touchGround = true;

                        isStuck = false;
                    }
                }
                catch (System.Exception)
                {
                }
            }
        }

        SetIsGrounded(touchGround);
    }

So PLZ what i am doing wrong?

2

943Ă—316 46 KB

3

No it doesn’t alloc even though it’s a (tentatively) deprecated method really. Take the “NonAlloc” suffix off any query and use that one which has all the overloads including List support. I nyour case, Physics2D.OverlapCircle.

Looks like it’s the callback that’s allocating. You can stop that by selecting Physics2D.reuseCollisionCallbacks (this is on by default though) so that the “Collision2D” instance is reused.

1 Like
4

BTW: Your code is wrong. You’re interating all the array if you get at least a single result. You should only iterate the result count that the query returns because this is all the call populates. Also, “playerTransform.localPosition” isn’t a world-space position; it’s a position relative to the parent.

5

i had already marked Physics2D.reuseCollisionCallbacks. In the code Physics2D.OverlapCircleNonAlloc that is why i find that so weird.Actually in the Profiler the name does not contains the “NonAlloc” part but i am using it.

6

Actually I just spotted that you are creating an array yourself:

Collider2D[] result = new Collider2D[10];

This will obviously produce garbage. You should reuse that array so take it outside that function.

As a side note: You’re much better off though using the overload that allows you to pass a “List” as that will grow only if needed and if not, no garbage

7

mmm…thanks for the little tips extra that i did not noticed before like that array inside. sadly OverlapCircleNonAlloc does not looks like having a List Overload.

8

I never said it did. As I said above, don’t use the deprecated NonAlloc calls. Just use “Physics2D.OverlapCircle” as I said. There you can use an array or list.

So do you follow what I said about the source of the garbage being you creating an array inside the function? I only ask because you didn’t acknowledge it.

9

Yes sorry, i realized for the array causing the Alloc, and i did not knew the NonAlloc was depercated :hushed:. Thanks

10

Yeah, it’s technically not deprecated because it would cause a lot of users to be frustrated but all 2D queries with “NonAlloc” suffix are tentatively deprecated. All 2D queries (without exception) have an overload that replaces these calls (that take an array) and also accept a list.

OverlapCircleNonAlloc → OverlapCircle
RaycastNonAlloc → Raycast
etc.

11

Great, i am already changing it to use ContactFilter and List. Many Thanks for your help

1 Like
12

Note that there’s a much easier method of detecting if something is grounded by using “IsTouching” and “IsTouchingLayers”: Unity - Scripting API:

You can an example of this in my GitHub repo. Here’s a video with links if you’re interested.

Good luck.

13

Wow i do not know how i did not found any reference to that before. It is the bad side of learn Everything on YouTube, ALMOST every body utilize the same functions. :slight_smile:

1 Like
14

Yes, I see this too. There’s a lot of use of “Raycast for everything” too!