ecs: `setCapacity` in the ECS doesn't adjust component arrays to reflect their new location within ArchetypeStorage #341

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opened 2022-06-11 13:21:32 +00:00 by tauoverpi · 0 comments

tauoverpi commented

2022-06-11 13:21:32 +00:00

(Migrated from github.com)

github.com/hexops/mach@1c0930b404/ecs/src/entities.zig (L152-L155)

This implementation of setCapacity assumes that component arrays have the same position after expanding capacity which ends up with them overwriting one another after expanding archetype storage as the position of each array is shifted forward by new_capacity - storage.capacity * size_of_previous_component.

Thus is should instead be closer to:

As far as I understand this implementation of it.

In short, setCapacity doesn't perform step 3 thus leaving arrays overlapping in memory.

https://github.com/hexops/mach/blob/1c0930b40464b9abc46de429609f58e2097d751f/ecs/src/entities.zig#L152-L155 This implementation of `setCapacity` assumes that component arrays have the same position after expanding capacity which ends up with them overwriting one another after expanding archetype storage as the position of each array is shifted forward by `new_capacity - storage.capacity * size_of_previous_component`. Thus is should instead be closer to: - https://gist.github.com/tauoverpi/6f4832a406e49ad112a88395fa787374#file-aecs-zig-L335 - https://gist.github.com/tauoverpi/6f4832a406e49ad112a88395fa787374#file-aecs-zig-L396 As far as I understand this implementation of it. ![layout](https://user-images.githubusercontent.com/45411401/173189709-8e2e44e4-c07f-4469-a1e0-a0ebcc76eb98.png) In short, `setCapacity` doesn't perform step 3 thus leaving arrays overlapping in memory.