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

1. Install Fabric Loader for 1.21.1.
2. Download Sable and place it in your mods/ folder.
3. Download this mod's JAR and place it in mods/.
4. 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

1. Detection: Breaking a log triggers a flood-fill search for connected logs, leaves, and attached blocks.
2. Validation: The detected structure is validated as a tree (must have a root on dirt or have leaves if rootless mode is on).
3. Assembly: Valid tree blocks are converted into a Sable ServerSubLevel — a physics-backed block container with independent collision and transform.
4. Flicker Fix: Original world blocks are replaced with BARRIER, then immediately AIR, preventing any visual flicker.
5. Impulse: A directional force and torque are applied based on the player's position, causing the tree to tip over.
6. 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.