Issue with ECS and blittable types

Unity Engine
,
1

Stated in MS doc, One-dimensional arrays of blittable types(like int[ ]) is blittable type, where Unity throws an error:

ArgumentException: DungeonQuest.Componants.HotBarComponant is an IComponentData, and thus must be blittable (No managed object is allowed on the struct)

when I using int[ ].
Here is my code that follow MS guide about blittable.

public struct HotBarComponant: IComponentData
    {
public int[] items
    }

Is there some Unity doc about what type of data types they support since they dont seem to support the types that MS state are blittable.

2

nvm struct and class that contain arrays of blittable is not blittable itself…why…lol

3

You may be interested in FixedArray instead.

2 Likes
4

For a IComponentData to be blittable it has to be a fixed size and be layed out linearly in memory. int[ ] itself is blittable but having a struct with a reference to it is not. Size is variable and actual content is stored somewhere else on the heap.

Or saying it differently: if it is a blittable type by Microsoft’s definition and it is a value type it should work.

5

The website you mentioned actually says so too:

The following complex types are also blittable types:

  • One-dimensional arrays of blittable types, such as an array of integers. However, a type that contains a variable array of blittable types is not itself blittable.