Getting per instance HISM data

[Dale_Wastell]

Hello awesome comunity. How do I save additional per instance data for a hierarchical instanced static mesh?

I have a game that simulates an ecosystem and am running into a problem with the hierarchical instanced static mesh. For preformance reasons, I am using multiple HISM objects to track plants (which spawn and get eaten etc). I need to store additional data for each mesh. Using objects in a lookup dictionary results in indexing problems - no matter what I try I can’t keep the indices matched. So I am looking at storing data in the material. I can easily add custom data into a material via the ‘set custom data value’ command but how do I retrieve these values?

As example, a plant instance needs to keep track of its spawn time for life span and size, the amount of nutrition it provides, its seeding cycle etc. so I need a fair amount of additional data for each mesh. I also need to be able to periodically loop through the HISM to update the size of the plants as they grow. I have all the logic in place and working but can’t get around the indexing problems as plants get eaten.

Please help
Thanks.

[Everynone]

In BPs that’d be a no-no. In C++ perhaps? Google confirms this exists:

GetCustomDataValueOnInstance

But I’ve never seen it done or even documented…

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Besides the above:

so I need a fair amount of additional data for each mesh

The official docs state one can store 32 floats, which is not true - at least it wasn’t in 4.27. The actual number is either 16 or 18 - last time I tested it. Which is still plenty but it’s just floats.

@Dale_Wastell

can’t get around the indexing problems as plants get eaten

How I do it:

• use the Tmap with key being the index and enjoy any data type via a struct
• never remove instances
• instead, move them where they can’t bother you; flag its hasBeenEaten map data appropriately
• bunny eats a carrot? That carrot now lives 5000 uus underground where no sensible bunny should go
• to regrow it, reuse one of the eaten carrot instances that lives underground
• at some point you’ll need to save it all - that’d be the time to trim the HISMc and repopulate the map from scratch

Think of this as of object pooling. The key is to not remove any HISM instances.

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Example:

How to add a hit count (health points) to individual instances?

The name of the game is Custom Primitive Data (check docs at the bottom). The material for a brick: each instance stores a float which is used to Lerp between 2 colours (to visualise hits remaining) this can (and probably should) get prettified [image] Making a brick wall: create a bunch of instances and store their data in an int | int Map instead of an integer, you could have a struct and hold all kind of data here; perhaps this brick is worth some coins, or explodes when destroyed an…

[Dale_Wastell]

Thanks for the reply, it appears that aside from the ‘plant purgetory’ with reincarnation which I don’t really like there is no viable solution. I have the same problem with seeds which disappear and spawn plants. If I need relocate everything and store a reincarnation array (souls awaiting liberation from hell and rebirth into the material world) to recycle things, Hell is going to be pretty crowded. Still, thanks for the reply - I guess I’ll start coding demigod Hades / Yamaraj…

I’ve done pretty extensive research and can’t seem to find any more elegant solution. If anyone knows of one, please share…