Occlusion

Description

Server-side anti-freecam. The server works out what each player can actually see and only sends that. Caves, bases and mobs out of sight are never sent, so freecam (or any client hack) has nothing to show. Hidden areas go out as plain stone and turn into the real blocks the moment they come into view, so legit players never notice.

On top of that you get raycast anti-xray (ores no line of sight reaches are sent as stone) and anti-ESP (entities behind walls aren't sent at all).

Screenshots

Freecam from inside the rock above a buried base:

Freecam deep underground, looking down. Vanilla sends every cave, mineshaft and base:

Mobs on the other side of a wall don't exist on the client until the player could see them:

Features

• Anti-freecam: every 16x16x16 section is checked with the client's own section walk plus line-of-sight rays underground. Sections ahead of a moving player are sent early, so nothing pops in.
• Raycast anti-xray: ores touching air that no line from the eye reaches are sent as stone. Sealed air pockets are filled too.
• Anti-ESP: every entity except projectiles gets a block-level line-of-sight check. Players within 32 blocks are always shown, glowing entities and boss bars stay.
• Dig reveal: what is behind the block you mine shows up before it breaks, so instant mining never shows stone.
• Third person (F5) cameras count as eyes.
• Bedrock players through Geyser are supported. Simple Voice Chat: hidden players' voices still play at their real position.
• API for other mods: PandaOcclusionApi.canSee(ServerPlayer, AABB) (holograms, fake entities).

Nothing breaks for legit players

• Full vanilla sound: the client makes many sounds itself from the blocks and mobs it has (lava pops, portal hum, fire, furnaces, spawners, warden heartbeat, blazes, totems, ...). Occlusion works those out on the server and sends them, so players still hear every block and subtle noise around them, hidden or not.
• Boss bars: a wither behind a wall still shows its health bar exactly like vanilla.
• Lighting: hidden areas come back with correct light, no black boxes.
• Instant mining: what is behind a block shows up as you start mining it, so you never see filler stone.

Performance and testing

• Bandwidth: chunk data drops to 0.30-0.40x of vanilla on login and while flying, 0.17-0.30x in the nether.
• Server cost: sight checks run on their own threads. On Hardcore Anarchy it costs ~0.4 ms per tick (0.8% of the server thread). 30 bots moving underground at once: 0.2 ms per check off-thread, ~0.02 ms per tick on the server thread.
• Raycast anti-xray: ores touching air but out of sight that still reach the client: 478 -> 18 in the test caves, 0 ores in plain view hidden by mistake.
• Testing: an automated suite of 36 bot tests runs every change against the last version, comparing every block and entity a player can see with a bot that gets the vanilla view. 0 wrong blocks in line of sight. Running on Hardcore Anarchy and Skyblock Anarchy since October 2026.

GrimAC Compatibility

Works with GrimAC, with one catch: when Occlusion resends the chunk a player is standing in, upstream Grim briefly counts the player as standing in an unloaded chunk and rubberbands them (no alert). The fix is one commit (35bf13c) in the TreeOfSelf/Grim fork, which both servers run.

Configuring

config/PandaOcclusion.json, generated on first start. Every feature has its own switch (hideEntities, hideUnseenOres, hideSealedPockets, revealBehindDig, thirdPersonCamera, hiddenSounds, ...).

Works well with an AntiXray mod: list the same natural blocks in AntiXray's hidden blocks and in keepHiddenUntilExposed.

Commands

Operator level 3:

• /occlusion reload, /occlusion stats
• /occlusion bypass: see everything yourself (toggle)
• /occlusion section <player> <pos>, /occlusion why <player> <entity id>: why something is hidden or shown

Kill switch: "enabled": false and /occlusion reload.

Try it out

hardcoreanarchy.gay (Deathban Anarchy)
sky.hardcoreanarchy.gay (Skyblock Anarchy)

More mods

• Anti-Exploit - A drop-in mod for preventing common exploits. Fully configurable and works well alongside other anti-cheats like GrimAC.
• GeyserAC - Anti-cheat for Bedrock players joining through Geyser: movement prediction, combat and block checks.
• No Lag - Stop common causes of lag on your server. Configure to your likings.
• Dupe Fix - A simple drop-in mod to prevent all forms of duping. TNT-Duping, Gravity block duping, and much more will not work with this mod enabled.

All my mods

Issues

Bugs and problems go on GitHub Issues. There is no Discord support.

License