JSON Entity Models (JEMS)

JSON Entity Models (JEMS) is a client-side Forge mod that completely replaces Optifine's Custom Entity Model system. The new system offers significantly greater flexibility and compatibility with other mods. JEMS is based on the GeckoLib library, which replaces Minecraft's standard Java models with JSON models. Since JSON files are much more flexible than Java files, they can be edited in almost any way, allowing for fully customized mob models, textures, and animations.

What Does JEMS Do by Default?

In its basic configuration, the mod includes a built-in resource pack that adds JSON models for several mobs, demonstrating the system's core capabilities. All these mobs have custom animations that preserve the spirit of vanilla Minecraft while adding more life to them. The built-in pack can be disabled if you prefer to keep everything vanilla or use only your own resource packs with JEMS.

JEMS Capabilities

What can you do with this mod? Here's a brief list:

• Create resource packs for any mobs - both from vanilla Minecraft and from other mods, giving them unique models, textures, and animations!
• And not just one of each element! Add random variations of models, textures, and animations for infinite variety!
• Remember how some mobs like Endermen, Phantoms, and Spiders have glowing eyes? Now you can easily add glowing elements to any mob, anywhere on their model!
• Previously, only humanoids like Zombies and Piglins could display items and armor? NOT ANYMORE! Any mob can display armor and items - even with fully custom models!

Which Mobs Already Support JEMS?

Currently, built-in JEMS resource packs are available for the following mobs:

• Zombie
• Skeleton
• Spider
• Creeper
• Cow
• Pig
• Sheep
• Chicken
• Iron Golem
• Enderman

These mobs also have additional built-in animations and features that are not yet available for other mobs (for example, cracked layers on iron golems). In future updates, we plan to add support for more creatures.

Where to Learn How to Create JEMS Resource Packs?

Great question! We have a wiki with detailed documentation on how JEMS packs work:

https://github.com/infernalstudios/JSON-Entity-Models/wiki

Are CEM Packs Compatible with JEMS?

No. But this shouldn't be a problem since working with JEMS is much simpler and more convenient than with Optifine packs!

Transferring packs from one system to another shouldn't cause major difficulties.

Issues and Support

If the game crashes when using a custom resource pack, the pack is likely incorrectly formatted and needs fixing.

If a crash occurs during gameplay and is related to JSON models, GeckoLib, or JEMS specifically, please let us know.

Planned Features

Features currently missing from JEMS but may be added in the future:

• Mob variations depending on biome
• Changes based on altitude (Y-level)
• Variations by nametags
• Influence of time of day and weather
• Animated textures

What JEMS Does NOT Do:

• Does not change hitbox sizes (use Pehkui!)
• Does not add custom mob AI (JEMS is a resource pack tool)
• Does not create sound variations (this is outside the project's scope)

About Development

We are actively working on project development! The developer is currently abroad, and the animator works on multiple different projects, so development pace may slow down after the initial release.

Nevertheless, we don't plan to abandon this project: we are both very passionate about it and look forward to adding more features in the future!

Acknowledgments

HellionGames - for programming Nekomaster - for creating mob models, textures, and animations GeckoLib - for supporting the project and making it possible Infernal Studios Discord members - for the energy to continue working on studio projects