Sorting a DynamicBuffer

Hello!

I'm wondering if there's a built in API, or standard approach to sorting a DynamicBuffer.

If there isn't, here are the existing options I'm aware of:

1.Convert DynamicBuffer to NativeArray -> Sort the NativeArray -> Assign values back to DynamicBuffer.
2. Write your own

Sort<T>()

or

OrderBy<T>()

extension for DynamicBuffer, which mimics .Net Sorting logic.

#2 Sounds fine, though I'd worry I could be clumsily stomping on Unity's design intentions for DBs.

Please sound off if you have better ideas.

 

DynamicBuffer has a AsNativeArray method and NativeArray has a Sort method that accept, IIRC, a IComparer implementation:

Code (CSharp):

1. public struct RaycastHitDistanceComparer : IComparer<RaycastHit> {
2.     public int Compare(RaycastHit lhs, RaycastHit rhs) {
3.         return lhs.distance.CompareTo(rhs.distance);
4.     }
5. }
6.  
7. DynamicBuffer<Foo> myBuffer;
8. var hits = myBuffer.AsNativeArray();
9.  
10. hits.Sort(new RaycasthHitDistanceComparer());

You can implement IComparer<T>, Comparer<T> or use Comparer<T>.Create.

[]'s

 

Thanks! That's #1, from the OP:

I'm concerned about unnecessary work here, that could have a (tiny, but cumulative) performance impact. It would be nice if we didn't have to create a new collection, sort it, make a bunch of assignments back to the DB, and then dispose of the middleman collection.

 

You don't have to worry about it.

AsNativeArray()

only creates a shadow copy to the actual

DynamicBuffer

contents, not a copy of the data.

 

Oh, rad! ...hmm, based on the way NativeCollections work, I should have guessed as much.

OK, well then that basically covers it. Thank you.

 

You don't need it, it's not a copy.
The NativeArray returned by AsNativeArray points to the same address of the DynamicBuffer.

[]'s