Question about ISharedComponent indexes

1. I noticed that when I create an entity with a new

ISharedComponent

(in an otherwise empty scene/world),

EntityManager.GetAllUniqueSharedComponentData(List)

returns with a length of 2; with index [1] containing the values of the new

ISharedComponent

I made, and index[0] with empty/default data.
I couldn't find if this is supposed to happen, but am guessing yes; since the empty/default data that is filled with zeros still counts as its own unique values, so it will always be there by default.

2. But if that is the case, then I have no idea what is going on here: In the same

OnUpdate

, after I call the

GetAllUniqueSharedComponentData

, I run a job and call

chunk.GetSharedComponentIndex(type)

and it returns an index of 3? And one frame later, in the

OnUpdate

the list returns length of 2 again, and the in the chunk the same thing happens and it gets an index of 3. I double checked that I'm calling both of these functions with the same

ISharedComponentData

type.

How I understand it is

GetSharedComponentIndex

is supposed to return the index specific to the type specified. e.g. if there are 3 different chunks which are separated by having different values of the same

ISharedComponentData

type, and these are the only chunks containing this type, calling

GetSharedComponentIndex

on each of them would return indexes 0, 1, and 2.

What happens in 1. makes sense, I just want to be double sure.. but what happens in 2. is completely puzzling to me.. maybe one can confirm my understanding?

All help appreciated, thanks.

 

https://gametorrahod.com/everything-about-isharedcomponentdata/

 

Hi eizenhorn,
Thank you for reminding me of this, I went and re-read it all and found the solution was to use:

GetAllUniqueSharedComponentData(SCDList, indexList);

I had misunderstood and assumed the

GetAllUniqueSharedComponentData(SCDList)

returned a list with matching indexes but since this isn't the case the key was to include the

indexList

parameter.
Thanks again