How do I keep a float3[,] or float3[][] or any other arrays in an IComponentData?

I know I can't do that because it's not a bittable type. So how do I go about it?

Is it better to keep it in a System? But if it's aJobComponentSystem, how do I pass it to the job?

 

IBufferElement

 

A dynamic buffer (implementing IBufferElementData) is what you should use. For a float[][] you can use the dynamic buffer (which is 1 dimensional) and convert your x,y indices into a single index using

array[width * row + col] = value;

.

 

If you have small amount of items, you can use a ResizableArray64Byte in your IComponentData.

 

I tried with float3[][], float[][][] and also float[] with the serialization method you mention but all of them give the same error saying it's neither a primitive nor a bittable type.

 

I'm not sure this is the right solution for me as I have a matrix of values which is technically a float3[][].
I tried to switch to ResizableArray64Byte<ResizableArray64Byte<float3>> but I had a runtime error saying that Capacity was 0 when I was sure I had it all initialized (with

new ResizableArray64Byte<ResizableArray64Byte<float3>>()

) and allocated using

new ResizableArray64Byte<float3>();

plus a number of

ResizableArray64Byte.Add(...)

I never used ResizableArray64Byte. Perhaps I have too many elements for ResizableArray64Byte?

 

You need to use a dynamic buffer (https://docs.unity3d.com/Packages/com.unity.entities@0.1/manual/dynamic_buffers.html) instead of an e.g. float[], with IBufferElement elements (the example on https://docs.unity3d.com/Packages/com.unity.entities@0.1/manual/dynamic_buffers.html uses an IBufferElement with an int) in place of the floats.

 

ResizableArray64Byte is a fixed 64 bytes buffer, so you can't definitely nest them. it should be treated as a 1-dimensional array where the total size is less or equals to 64 bytes.

I agree that it's not the right solution if you have a huge matrix. DynamicBuffer are probably your best bet.

 

Here are some code fragments of using a dynamic buffer.

Code (CSharp):

1. //define data type
2. public struct MyData : IDynamicBufferElement
3. {
4.     public float value;
5. }
6.  
7. //add data
8. entityManager.AddBuffer<MyData>(entity);
9.  
10. //access from main thread
11. var buffer = EntityManager.GetBuffer<MyData>(entity);
12.  
13. //access from job where lookup is BufferFromEntity<MyData>
14. var buffer = lookup[entity];
15.  
16. //adding an element
17. buffer.Add(new MyData { value = afloatvalue });
18.  
19. //accessing 1d array
20. var value = buffer[index].value;
21.  
22. //accessing 2d array
23. var value = buffer[width * row + col];

 

Thanks Florian. I'm sure I'll sound confused now. Is this really what fits considering the size would not change in dimension?
Is it the best way to go to have a collection of float3? Do I have to implement a separate system to get/set these values or can I read from an existing one??

Maybe my problems are more specific to my situation than I thought. Again, the goal here is to have a matrix of float3. I don't get how I make this visible to any Systems I create.
If I have a System that acts on some (many) moving entities and these entities have to get a value from a force field (a float3[][] type) it sounds like it should be trivial to me.

 

Here are two ways you could approach this problem:

1. You could have your system that moves your entities with respect to the force field store the force in a native container similar to a float[][] (you could write a custom container or use a 1 dimensional native array with an index mapping scheme) allocated by that system.

2. Have each cell of the force field be an entity that has component data:

struct ForceFieldPoint : IComponentData{ float value; }

. You would position these entities in a grid to form your force field. They would then be accessed with a query looking for entities with a ForceFieldPoint component.