Passive Mob Spawn

Passive Mob Spawn is a lightweight server-side NeoForge mod for skyblock modpacks where passive animals need to spawn naturally on player-made grass platforms, even high in the sky.

The mod adds a controlled supplemental passive mob spawner that looks for valid grass_block platforms around players and attempts to spawn configured passive animals during the day.

Features

• Allows passive mobs to spawn on grass platforms at any build height.
• Designed for skyblock worlds and void-style progression packs.
• Runs server-side and does not require client-side installation.
• Only attempts spawning during daytime.
• Supports weighted mob entries such as minecraft:cow=100.
• Supports configurable spawn check delay.
• Skips spawns too close to the player.
• Checks nearby mobs of the same type to reduce overcrowding.
• Includes optional debug logging for spawn attempts and denial reasons.

Spawn Conditions

The mod searches for valid spawn positions around players. A position is considered valid when:

• The base block is minecraft:grass_block.
• The block above is air, short grass, tall grass, fern, or a flower.
• The position is at least 16 blocks away from the player.
• The dimension is currently daytime.
• The local passive mob cap has not already been reached.
• There are fewer than 2 mobs of the same type within 16 blocks of the target position.
• The selected entity passes its normal Minecraft spawn, obstruction, and collision checks.

Configuration

After launching once, the config is generated at:

config/passivemobspawn-common.toml

Example:

Config Options

• debug: Enables detailed console logs for spawn checks, selected mobs, valid positions, and denial reasons.
• spawnCheckDelaySeconds: Delay between spawn checks. Higher values make passive mobs spawn less often.
• passiveMobs: Weighted list of entity ids the mod may spawn.

Weighted Mob Entries

Use entity_id=weight format:

• minecraft:cow=100
• minecraft:sheep=50
• minecraft:rabbit=10

Plain ids such as minecraft:cow are also accepted and use weight 1. Blank entries are ignored.

Recommended For

• Skyblock modpacks
• Void worlds
• Progression packs where grass platforms should support passive animal spawning
• Servers that need configurable, controlled passive mob generation