[1.18.1] Detecting trees

[NJSwede]

Hello again!

Is there a convenient way to determine whether a log block is part of a tree? I could always scan the surroundings for leaves, but it's not 100% reliable. Does Minecraft even record the presence of a tree or is it just a bunch of log and leaf blocks? 

[Draco18s]

20 minutes ago, NJSwede said:

Does Minecraft even record the presence of a tree or is it just a bunch of log and leaf blocks? 

Nope, its just a bunch of log and leaf blocks.

This is the best I was ever able to do (warning, very very old code):
https://github.com/Draco18s/HarderStuff/blob/master/src/main/java/com/draco18s/wildlife/util/TreeCountGenerator.java#L55

[OutCraft]

If you scan for leaves scan for persistent=false leaves (persistent is a blockstate, you can see it with F3). These are the leaves at trees and break if there is no log near. If the player places leaves they are persistent=true and don't need a log block, so only tree leaves will be detected as there is no way in survival to place persistent=false leaves

[Draco18s]

But that doesn't solve the issue of where the "tree" is.

[OutCraft]

20 minutes ago, Draco18s said:

But that doesn't solve the issue of where the "tree" is.

It wasn't supposed to, just a hint if he scans for leaves:

1 hour ago, NJSwede said:

I could always scan the surroundings for leaves

Edit: Sorry if I expressed it wrong 

Edited January 27, 2022 by OutCraft

[NJSwede]

@OutCraft is probably close enough for what I'm doing. I'm working on an enchantment that lets you take down a tree in a single strike (I know it's been done a million times, but I'm educating myself). I'd like a safeguard so it doesn't take down an entire log house by mistake, so occasional false positives aren't not that much of an issue.

[Draco18s]

The best description of a "tree" is "a wood block above a dirt block with more wood blocks on top with leaves nearby." With the leaves being in at least one of the 17 other positions around the top-most log in the stack (also those positions might have more logs, and if you find one, keep checking in the adjacent new 25 for more logs in order to detect big trees).

Knowing "these leaves are part of a tree" doesn't help identify if the player "chopped down the whole tree."

[NJSwede]

40 minutes ago, Draco18s said:

The best description of a "tree" is "a wood block above a dirt block with more wood blocks on top with leaves nearby." With the leaves being in at least one of the 17 other positions around the top-most log in the stack (also those positions might have more logs, and if you find one, keep checking in the adjacent new 25 for more logs in order to detect big trees).

Knowing "these leaves are part of a tree" doesn't help identify if the player "chopped down the whole tree."

Great minds think alike!  Sounds like what I was thinking of doing.

[NJSwede]

On 1/27/2022 at 2:03 PM, Draco18s said:

The best description of a "tree" is "a wood block above a dirt block with more wood blocks on top with leaves nearby." With the leaves being in at least one of the 17 other positions around the top-most log in the stack (also those positions might have more logs, and if you find one, keep checking in the adjacent new 25 for more logs in order to detect big trees).

Knowing "these leaves are part of a tree" doesn't help identify if the player "chopped down the whole tree."

So this is what I ended up doing: A simple 3D flood fill of the trunk while detecting adjacent leaves of the correct type. I didn't bother to check for a dirt block at the root, since it didn't make much of a difference for what I wanted to do. It would be fairly easy to do.

Probably not the most efficient algorithm, but since trees and ore veins are relatively small, it's fast enough. 

Posting the code for your viewing pleasure. The only thing I wonder if there's a more efficient way of digging out the "persistent" property.

https://gist.github.com/prydin/cc48a3ddd645bcd6f73d63bac6aa75b7

[Draco18s]

3 hours ago, NJSwede said:

but since trees and ore veins are relatively small, it's fast enough

He says before finding a birch forest.

 

3 hours ago, NJSwede said:

The only thing I wonder if there's a more efficient way of digging out the "persistent" property.

https://gist.github.com/prydin/cc48a3ddd645bcd6f73d63bac6aa75b7#file-featuredetector-java-L94-L97

You should be able to do an instance-of check against the LeafBlock class.  Also note that other mods may not use "xxx_leaves" for their leaves, but might do "yyyleaves" or "zzzleafblock"

As for the property:
https://github.com/Draco18s/ReasonableRealism/blob/1.14.4/src/main/java/com/draco18s/harderores/EventHandlers.java#L39

[NJSwede]

LOL! Luckily this code is only used for detecting one tree at the time, i.e. answering the question "is this block part of a tree". For counting trees in a birch forest, it's probably way too slow.

 

Thanks for the rest of the pointers. I'll give it a shot!

[Draco18s]

I meant that you don't want your code leap frogging from "tree" to "tree" when they're close enough together.

Brich forest is probably fine, but the dark oak forest might be worth a test to make sure it doesn't take out the whole forest (ignoring item durability if you abort when it breaks).

Edited January 31, 2022 by Draco18s