Entity Detectors

Two blocks make up the core of the mod. A detector set to players emits a redstone signal when a player is near it, and a mob detector emits one when any mob is near. Each block's detection range can be cycled through 2, 4, 8 and 16 blocks, measured as a spherical radius, so one block can cover a small room while another watches a wider area. Redstone signals from these blocks can drive doors, lights, traps or alarms in an ordinary build.

A mob detector can be narrowed to a single type of entity. This is done with a Slimeball: shift-right-clicking a mob that is attacking with a Slimeball yields an Imprinted Slimeball, and using that item on a mob detector limits it to that mob type. Breaking the block with a regular Slimeball resets it to detect any entity again. Blocks check for entities once every 10 ticks by default, and that rate can be changed in the server config.

Installation needs Forge or NeoForge for Minecraft 1.20.1. Entity Detectors runs on client and server, so the server and every player need it. The source code and issue tracker are public, and the mod is released under the MIT License as open source. Files exist for 1.20.1 only, with 3.0.0.0 as the latest file for both loaders.