Structure and Feature placement callbacks

[octylFractal]

Major SpongeAPI version

12

Is this likely to be a breaking change?

No

What are you requesting?

Currently, Structure and Feature have boolean place(ServerWorld, Vector3i), which does not allow a mod like WorldEdit to capture or modify the changes. It would be nice if we could get a callback for each block/entity so that WorldEdit may place it, rather than placing it directly into the world. This allows undo, masking, and better control of block placement than using Minecraft's code directly.

[Yeregorix]

I think the proper way to do it would be:

try (CauseStackManager.StackFrame frame = Sponge.server().causeStackManager().pushCauseFrame()) {
  frame.addContext(MY_CONTEXT_KEY, "hello");
  Features.TREES_PLAINS.get().place(location);
}

and

@Listener
public void onBlockChange(ChangeBlockEvent e) {
  if (e.context().get(MY_CONTEXT_KEY).isPresent()) {
    // filter blocks
  }
}

However I tested that a few days ago and it didn't work so there is likely a bug in the implementation currently.
The implementation needs to be fixed, but I don't think the API needs any additions for that.

[aromaa]

I have fixed the implementation for the suggested and recommended approach mentioned above in the commit SpongePowered/Sponge@49fe76a. This should unblock any scenarios where you would want to modify or record the block changes.

I will leave this open however because we most likely would like to still implement some improvements around this where you only want to record the outcome. Something along the lines of 63edbff#diff-18baa7adfaf0c306829fb40fb9aeccd21a7885830d19064a07504aaf3d0d361fR106. We have introduced CompositeEvent in API 14 which seems to be the perfect candidate here.