Dynamic Falling Tree

Realistic tree falling physics for Minecraft 1.21.1 (Fabric). When you chop a tree, it falls over using rigid-body physics instead of instantly disappearing.

Tree falling demo

In-game screenshot

What It Does

Chopping the base log of a tree causes the entire tree to tip over and fall using real physics simulation.
Blocks are removed flicker-free via a BARRIER -> AIR sequence in the same server tick.
Trees spawn impact smoke particles when they hit the ground.
Leaves break naturally after the tree settles, with vanilla particle effects.
Works on rootless/floating trees as well as grounded ones.

Requirements

Dependency	Version
Minecraft	1.21.1
Fabric Loader	>= 0.16.9
Fabric API	>= 0.110.0+1.21.1
Sable	>= 1.2.2

Installation

Install Fabric Loader for 1.21.1.
Download Sable and place it in your mods/ folder.
Download this mod's JAR and place it in mods/.
Launch and chop a tree.

Configuration

Config file auto-generates at .minecraft/config/treephysics.properties:

rootless_tree_detection=true
requires_axe=false
prevent_interacting_with_trees=true
rooted_dirt_generation=true
impulse_torque=2.0
impulse_force=1.5

Option	Description	Default
`rootless_tree_detection`	Allow floating trees to fall.	`true`
`requires_axe`	Only trigger physics when holding an axe.	`false`
`prevent_interacting_with_trees`	Block placing/using items on falling trees.	`true`
`rooted_dirt_generation`	Generate rooted dirt under naturally spawned trees.	`true`
`impulse_torque`	Rotational force applied to falling trees.	`2.0`
`impulse_force`	Linear push force applied to falling trees.	`1.5`

How It Works

Detection: Breaking a log triggers a flood-fill search for connected logs, leaves, and attached blocks.
Validation: The detected structure is validated as a tree (must have a root on dirt or have leaves if rootless mode is on).
Assembly: Valid tree blocks are converted into a Sable ServerSubLevel — a physics-backed block container with independent collision and transform.
Flicker Fix: Original world blocks are replaced with BARRIER, then immediately AIR, preventing any visual flicker.
Impulse: A directional force and torque are applied based on the player's position, causing the tree to tip over.
Impact & Decay: While falling, the server tracks velocity. Ground contact spawns smoke particles. After settling, leaves break naturally.

Technical Details

Built on the Sable physics engine using SubLevel rigid-body simulation.
All physics runs server-side and syncs to clients over the network.
Singleplayer and multiplayer compatible.
Licensed under MIT.