SentinelLib
by OmbreMoon
SentinelLib is a NeoForge library for defining custom combat hitboxes on mobs, with rotating and scaling boxes for melee attacks.
What it does
Minecraft checks melee reach by measuring whether an entity sits within a set distance of its target, and it does not render hitboxes natively, so it limits them to axis-aligned bounding boxes. SentinelLib lets a developer define hitboxes as AABBs or as oriented bounding boxes and rotate them, then attach custom behavior that triggers when an entity's attack hitbox touches a target. Doing this by hand for each attack tends to repeat the same collision code across a mod, and the library moves that logic into one place.
Sentinel boxes can rotate and scale dynamically, which lets a mob's attack follow its animation instead of a fixed zone. The library also supports Geckolib, with GeoBone-based Sentinel Boxes that take their shape from a model's bones. The stated purpose is making mob combat more engaging than a plain distance check, and the author notes the project is still in beta with some functions planned for later builds.
SentinelLib runs on client and server, so the server and every player need it. Files are published for NeoForge 1.21.1 only, with sentinellibneo-1.1.6-1.21.1 as the latest file, released 2026-01-11. The source code is public under the GNU General Public License v3.0 only.
Key features
Rotating sentinel boxes
Hitboxes can be rotated to follow the direction a mob faces or swings.
Scaling sentinel boxes
A hitbox can grow or shrink during an attack, so its reach matches the animation.
Geckolib bone hitboxes
GeoBone-based sentinel boxes take their shape from Geckolib model bones.
Oriented bounding boxes
Hitboxes can be oriented bounding boxes as well as axis-aligned ones.
Custom attack logic
Developers attach their own functionality to the hitboxes that hit a target during movement.
Compatibility
Latest build for each game version and loader.
Only full game releases are shown. This mod publishes no snapshot builds.
Use cases
Mob melee attacks
A mob's swing can be tied to a hitbox that moves with its attack animation, replacing a plain distance check.
Boss encounters
Larger scaling hitboxes can cover the reach of a boss's sweeping or slamming attacks.
Who it’s for: The library is aimed at mod developers who write mob combat and want to avoid repeating hitbox collision code. Players see its effects only through the mods that use it.
Questions
Does SentinelLib need to be installed on both sides?
Which loader and game version does SentinelLib support?
Does SentinelLib support Geckolib models?
What the author says
This is a small lib made out of necessity that's only purpose is to make mob combat a bit more engaging. The typical way Minecraft handles melee combat is checking whether an entity is within a certain distance of another entity and dealing damage, which is kinda boring. Then of course you can apply a hitbox to every…
Official listing
- Modrinth page
- modrinth.com/mod/sentinellib
- Owner
- OmbreMoon
- Published
- 2026-01-11
- Updated on Modrinth
- 2026-01-11
- Facts verified
- 2026-10-15