Rentities — GPU Instanced Entity Rendering

Minecraft 1.21.11 | Fabric | Requires Sodium

⚠️ Alpha — Proof of Concept Release This is the first public release. The core rendering system works and delivers real performance gains, but several visual issues are known and will be fixed in future updates. Do not use on important worlds without backups.

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What it does

Vanilla Minecraft issues a separate draw call to the GPU for every entity on screen. 500 cows means 500 draw calls. Rentities intercepts the entity render loop and batches all entities of the same type into one instanced GPU draw call, uploading positions, rotations, and animation state via a Shader Storage Buffer Object (SSBO). All per-bone animation is computed in a custom GLSL vertex shader — the CPU does no animation work at all.

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Benchmarks

RTX 5070 · Minecraft 1.21.11 · Sodium 0.8.6 · Lithium · Render distance 20 · ~3000 entities in view

Setup	Avg FPS	1% Low
Sodium + Lithium	122	70
Sodium + Lithium + Rentities	311	145

+155% average FPS. +107% improvement in 1% lows.

Rentities and Lithium are complementary — Lithium reduces CPU server tick cost, Rentities reduces GPU draw call overhead. Together they compound.

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Requirements

• NVIDIA GPU (GTX 10 series or newer)
• Fabric Loader 0.17.2+
• Sodium 0.8.6
• Minecraft 1.21.11

Works standalone. Does not require Nvidium, though both mods are compatible and stack together.

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In-Game Settings

Sodium → Video Settings → Rentities

Option	What it does
GPU Entity Batching	Master on/off toggle. Takes effect immediately without rejoining
Entity Scan Mode	ON = extract and save meshes to disk. OFF = load from saved cache. Rejoin world after changing
Mesh Cache	Shows whether a cache file exists on disk
Delete Mesh Cache	Clears the cache so it gets rebuilt on next world load

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Known Issues — Will Be Fixed

This is a proof of concept release. The following are known and actively being worked on:

Armor stand rendering Armor stands always render facing one fixed direction regardless of how they were placed or rotated in the world. Pose data set via /data commands (angled arms, bent legs, custom poses) is completely ignored — they always display in the default standing position. This is a known limitation of the current pose extraction system.

Entity facing direction Some entities appear to face the wrong direction compared to where they are actually looking in the world. When you disable Rentities and use vanilla rendering, the same entity may be facing a different direction. This is a yaw/rotation calculation bug being investigated.

Animations are approximate Walk cycles, idle animations, and limb movement work but are not 1:1 with vanilla. Some entities move their limbs in ways that look slightly off compared to the vanilla renderer. Full vanilla animation accuracy is a planned future improvement.

Texture facing issues On some entity types, textures appear mirrored, flipped, or applied to the wrong side of a model part. This is a UV coordinate issue in the mesh extraction pipeline.

Head offset The head on some entity types appears slightly rotated or offset from where it should be relative to the body.

Unscanned entities show as magenta cubes Any entity type that was not present when the mesh cache was built will appear as a spinning magenta placeholder cube. Enable Scan Mode and rejoin a world containing those entities to fix it.

No Iris/shader support Entities rendered by Rentities appear unlit and flat when shader mods like Iris are active. Disable Rentities when using shaders for now.

AMD and Intel GPUs not yet supported The mod detects NVIDIA and disables itself on other vendors. AMD/Intel support is planned.

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Planned

• Fix armor stand pose reading
• Fix entity facing direction
• Vanilla-accurate animations
• Fix texture UV orientation issues
• Indirect draw calls with GPU-side frustum culling
• Skip vanilla render state allocation for batched entities entirely
• Player skin rendering
• AMD and Intel support
• Iris compatibility

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FAQ

Does this work without Nvidium? Yes, completely standalone.

Does this work with Nvidium? Yes, they are compatible. Nvidium handles terrain, Rentities handles entities.

Why does toggling batching off/on in settings work instantly? The renderer is created and destroyed at runtime without requiring a world reload.

Why NVIDIA only right now? AMD/Intel support is coming. The rendering code itself uses standard OpenGL 4.5 — the restriction is temporary while stability is confirmed.

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Consider Supporting

Rentities is free and open source. If it helped your performance and you want to support continued development:

→ Patreon

No obligation — enjoying it and sharing it is already more than enough.

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Fun Fact

The name Rentities comes from Re + Entities — a nod to the fact that the entire entity rendering pipeline was rewritten from the ground up. It also sounds like "re-entities", which is exactly what this mod does: takes vanilla entities and gives them a fundamentally different rendering path.

The core vertex shader that handles all 21 animation categories is 500+ lines of GLSL and runs entirely on your GPU. Your CPU has no idea how any of those zombies are moving.

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MIT License · BalancingLight · Minecraft 1.21.11