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post: merge into single GPU-skinned herds article

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---
title: "GPU-Skinned Herds: One Draw Call for 1,000 Animated Characters in Godot"
slug: gpu-skinned-herds
date: "2026-06-14"
description: "Godot has no built-in way to render 1,000 skinned characters in one draw call. We built a GPU skinned-instance renderer into Tinqs Engine that does — 25 crocodiles verified, 1,000+ projected. Pre-built binaries for macOS and Windows."
og_description: "One draw call, 1,000 animated characters. GPU-skinned herd renderer built into the Tinqs Engine fork of Godot."
date: "2026-06-15"
description: "Godot has no built-in way to render 1,000 skinned characters in one draw call. We built a GPU-driven crowd animation platform into Tinqs Engine that does — 1,000 animals at 60 FPS, each with its own clip and phase, zero per-frame CPU. Pre-built binaries for macOS and Windows."
og_description: "One draw call, 1,000 animated characters, zero CPU. GPU-driven crowd animation platform built into the Tinqs Engine fork of Godot."
og_image: "https://www.tinqs.com/img/og-cover.jpg"
excerpt: "Godot can't batch-render 1,000 animated characters. We built a GPU skinned-instance herd renderer into the engine itself — already driving crocodile herds in Ariki. Pre-built editor binaries for macOS and Windows."
excerpt: "Godot can't batch-render 1,000 animated characters. We built a GPU-driven crowd renderer into the engine itself — bake every animation frame into a texture once, let the GPU drive every instance. 1,000 animals, 60 FPS, zero skeletons. Pre-built editor binaries."
author: "Ozan Bozkurt"
author_initials: "OB"
author_role: "CTO & Developer, Tinqs"
---
Godot gives you one `Skeleton3D` per character. Want 200 animals in a herd? That's 200 skeleton nodes, 200 draw calls, and 200 `AnimationPlayer` ticks every frame. Want 1,000? Now you're measuring in seconds per frame, not frames per second.
Godot gives you one `Skeleton3D` per character. Want 200 animated animals? That's 200 skeleton nodes, 200 draw calls, and 200 `AnimationPlayer` ticks every frame. Want 1,000? You're measuring in seconds per frame.
We built a GPU skinned-instance renderer into Tinqs Engine that packs every pose into a single texture, uploads once, and draws every instance in one call. 25 crocodiles confirmed first. Then we threw 1,000 animals — 12 types mixed, random-walking — at it and the GPU didn't flinch. Same bone count, same animation fidelity, a tiny fraction of the cost.
We built a GPU-driven crowd animation platform into Tinqs Engine that doesn't use skeletons at all. It bakes every animation frame into a bone-matrix palette texture once, and the GPU drives every instance's playback from then on. 1,000 animals at 60 FPS on integrated graphics. Each plays its own clip at its own speed and phase. Zero per-frame CPU cost. This is how AAA engines do crowds — and now it runs in our Godot fork.
## Why the engine needs to change
The standard Godot approach — one `Skeleton3D` + one `MeshInstance3D` per character — works for a handful of animated entities. It breaks down hard at crowd scale:
- **CPU bone transforms.** Computing `global_pose` for 200 skeletons × 100 bones each = 20,000 matrix multiplies per frame, all on the main thread.
- **CPU bone transforms.** Computing `global_pose` for 1,000 skeletons × 60 bones each = 60,000 matrix multiplications per frame, all on the main thread.
- **Draw call explosion.** Each `MeshInstance3D` is its own draw call. Even with MultiMesh, there's no built-in path for skinned meshes — `MultiMeshInstance3D` only handles static geometry.
- **AnimationPlayer sprawl.** Each skeleton needs its own `AnimationPlayer` and its own `process()` tick.
The alternative — baking animations to vertex textures — works for static crowds but locks you out of per-instance variation. No blending, no phase offsets, no reactive behaviour.
Vertex animation textures (VAT) can solve this — bake every vertex position into a texture and sample it in the shader. But that stores **vertices × frames**, not bones × frames. A 2,500-vertex animal with 500 animation frames needs 14 MB of VAT data. For 30 animal types: 426 MB. That doesn't fit on a Steam Deck. And VAT can't blend frames for smooth playback, can't skin normals for correct lighting, and locks you into one animation per bake.
What we need is simpler: **share the skeleton, drive per-instance poses from a single animation, batch the draw call.** That's what `agent_skinned` does.
Our answer: **bone-matrix palette.** Bake every bone pose into a texture, keep the skinning in the shader. The GPU samples the bone matrices and skins the mesh itself — same 4-bone linear blend as a real skeleton, same correct normals and tangents. But the CPU never touches a bone.
## How it works: two classes, one texture
The module lives in `modules/agent_skinned/` inside [Tinqs Engine](https://tinqs.com/tinqs/engine). Two classes, one job:
The module lives in `modules/agent_skinned/` inside [Tinqs Engine](https://tinqs.com/tinqs/engine). Two classes, one job.
### `MultiSkinnedMeshInstance3D` — the data plane
Holds the CPU-side bone matrices. Allocates an `ImageTexture` of size `[4 × max_bones, max_instances]` in RGBA32F — each texel is one column of a 4×4 bone matrix. For a 130-bone crocodile with 256 instances:
Holds the bone-matrix palette. Allocates an `ImageTexture` of size `[4 × max_bones, total_frames]` in RGBA32F — each texel is one column of a 4×4 bone matrix, each row is one baked animation frame. At load time, we play every animation clip on a temporary skeleton and record the bone matrices for every frame:
```
Texture: 520 × 256 RGBA32F ≈ 2 MB
Goat: 53 bones × 9 clips × 496 frames
Texture: 212 × 496 pixels, RGBA32F
VRAM: 212 × 496 × 16 bytes = 1.6 MB
```
That's the entire pose state for 256 animated crocodiles in a single GPU texture. The API is simple:
That's every frame of every clip — walk, run, idle, attack, death, eat, sleep — in 1.6 MB. Across 30 animal types: **48 MB total.** Compare to VAT at 426 MB. Bone-matrix is 9× smaller because bones ≪ vertices.
After the bake, the skeleton is destroyed. It never runs again. The API is straightforward:
```gdscript
var data := MultiSkinnedMeshInstance3D.new()
data.set_mesh(crocodile_mesh)
data.set_skeleton(skeleton) # rest pose + bone hierarchy
data.set_max_instances(256)
data.set_max_bones(130)
data.set_max_bones(53)
data.set_max_instances(496) # palette rows = baked frames
# Each frame: push poses from the animated skeleton
for instance in herd_positions:
data.set_instance_pose_bones(instance.id, bone_transforms)
data.update() # upload only dirty instances, not the whole texture
# Bake: play each clip, seek to each frame, record bone matrices
for clip in clips:
for frame in clip.frames:
skeleton.seek(frame.time)
data.set_instance_pose_bones(row, bone_transforms)
```
The data plane stores matrices column-major — 4 texels per bone = 4 columns of a 4×4 transform. The getter matches the layout, and a doctest asserts it so a transpose can't silently regress.
### `MultiSkinnedInstance3D` — the renderer
A `MultiMeshInstance3D` subclass. Set its multimesh with the skinned mesh and instance transforms, point it at the data plane, call `refresh()` — it uploads the bone texture into the shader material's `bone_matrices_tex` uniform and the mesh is drawn in one call.
A `MultiMeshInstance3D` subclass. Set its multimesh with the skinned mesh and instance transforms, point its `data_source_path` at the data plane. Call `refresh()` once — it uploads the bone texture into the shader material's `bone_matrices_tex` uniform.
The shader does 4-bone linear-blend skinning on the GPU:
Each MultiMesh instance carries 4 numbers in `INSTANCE_CUSTOM` (enable `multimesh.use_custom_data`):
| Channel | Meaning |
|---------|---------|
| `.x` | Which clip (start row in the palette) |
| `.y` | How many frames in this clip |
| `.z` | Playback rate (baked-fps × ground speed — foot-sync) |
| `.w` | Phase offset (golden-ratio spread — no two adjacent animals share the same frame) |
The vertex shader derives each instance's current frame from TIME:
```glsl
mat4 get_bone(int b) {
return mat4(
texelFetch(bone_matrices_tex, ivec2(b * 4 + 0, INSTANCE_ID), 0),
texelFetch(bone_matrices_tex, ivec2(b * 4 + 1, INSTANCE_ID), 0),
texelFetch(bone_matrices_tex, ivec2(b * 4 + 2, INSTANCE_ID), 0),
texelFetch(bone_matrices_tex, ivec2(b * 4 + 3, INSTANCE_ID), 0)
);
}
float fpos = mod(TIME * INSTANCE_CUSTOM.z + INSTANCE_CUSTOM.w * INSTANCE_CUSTOM.y,
INSTANCE_CUSTOM.y);
int f0 = int(fpos);
int f1 = int(mod(float(f0) + 1.0, INSTANCE_CUSTOM.y));
float fr = fpos - float(f0);
// Blend between two adjacent frames for smooth playback at low bake fps
int r0 = int(INSTANCE_CUSTOM.x + 0.5) + f0;
int r1 = int(INSTANCE_CUSTOM.x + 0.5) + f1;
// For each bone (up to 4 per vertex), reconstruct mat4 from 4 texels, blend, weight
mat4 m0 = mat4(
texelFetch(bone_matrices_tex, ivec2(b*4 + 0, r0), 0),
texelFetch(bone_matrices_tex, ivec2(b*4 + 1, r0), 0),
texelFetch(bone_matrices_tex, ivec2(b*4 + 2, r0), 0),
texelFetch(bone_matrices_tex, ivec2(b*4 + 3, r0), 0));
mat4 m1 = mat4( /* same for r1 */ );
skin += (m0 * (1.0 - fr) + m1 * fr) * weight;
// Apply skin to vertex, normal, tangent
VERTEX = (skin * vec4(VERTEX, 1.0)).xyz;
NORMAL = normalize((skin * vec4(NORMAL, 0.0)).xyz);
```
`INSTANCE_ID` is a Godot built-in — the GPU already knows which instance it's rendering. We just use it to index into the bone texture. No uniform arrays, no SSBOs, no compute shaders. Just a 2D texture and a custom vertex shader.
The shader uses `INSTANCE_CUSTOM` to pick the palette row — not `INSTANCE_ID`. This is the key: the texture's rows are baked animation frames, not per-instance slots. Many instances share the same rows (a synchronized airborne flock) or each pick their own (a varied herd). One abstraction, two behaviors.
## Two bugs we shipped and fixed
The blend between two adjacent frames means we can bake at a low fps and stay smooth — the shader interpolates. The golden-ratio phase spread means every animal in a herd reads a different frame. One draw call per animal type. Zero CPU. Per-instance clip, speed, and phase — all in the GPU.
The module had data-plane doctests from day one — round-trip pose get/set, dirty tracking, size clamping, AABB. All green. Then we put it on screen for the first time and the crocodiles looked... wrong.
The shader ships as the default material on `MultiSkinnedInstance3D`. It includes an `albedo_tex` uniform — the caller sets it from the source mesh's material so herds texture out of the box. No `ShaderMaterial` assembly required unless you want custom shading.
**Bug 1: Shader compile failure.** The default skinning shader compared `TANGENT` as `vec4`. Godot 4 exposes it as `vec3`. Fixed in one line, added `albedo_tex` uniform so herds texture out of the box.
## The numbers
**Bug 2: Bone matrices stored transposed.** The data plane wrote basis rows (standard Godot `Transform3D.basis` is row-major), but the shader unpacked as columns. Every bone matrix was transposed — the mesh crumpled. Not a scale bug, not an orientation bug — a layout mismatch. Fixed by storing column-major, with a doctest to prevent regression.
Measured on an M1 Pro MacBook Pro (integrated GPU):
The lesson: doctests catch logic. Rendering catches truth. You need both.
| Agent count | FPS |
|------------|-----|
| 100 | **60** |
| 500 | **60** |
| 1,000 | **60** |
| 10,000 | 8 (with CPU-side culling, pre-optimization) |
**VRAM:** 1.6 MB per animal type. 30 types = 48 MB total. A Steam Deck with 1 GB shared memory fits the entire roster.
**Draw calls:** One per animal type. 30 types = 30 draw calls for every animated animal on screen. Future colonists share the same architecture — one draw call per colonist look.
## What's driving it
In [Ariki](https://www.arikigame.com), the sim tracks animal migration across a 12km archipelago. `AnimalHerdRenderer.cs` groups sim `ViewerState.animals` by type, feeds positions to `skinned_herd.gd` (a reusable per-type herd backend), which drives the renderer. One `AnimationPlayer` animates a single driver skeleton; poses propagate to every instance.
In [Ariki](https://www.arikigame.com), the sim tracks animal migration across a 12km archipelago. `AnimalHerdRenderer.cs` groups sim `ViewerState.animals` by type, feeds world positions and yaw rotations to `skinned_herd.gd` — the reusable per-type herd backend. The herd bakes the palette once at setup, then `set_positions()` updates transforms each sim tick. `set_clip_for_state()` switches the active clip block in the custom data when the sim FSM changes state. `set_speed_scale()` adjusts the per-instance playback rate to match ground speed — feet stay planted.
The crocodile herd scene was 25 instances, one draw call. The perf test scene does 1,000 animals across 12 types — Boar, Cow, Crab, Crocodile, Deer, Fish, Goat, Hen, Pig, Rabbit, Sheep, Tiger — each type its own GPU herd, all mixed, all random-walking, FPS holding steady.
The sim owns all behavior — 30 data-driven animals with per-animal senses, diet, combat stats, and FSM states (graze, drink, sleep, hunt, flee, scavenge, die). The client just renders. This is the same code in single-player and multiplayer — the sim is the host.
Bird flocks use the same system. `BirdFlock.cs` runs boid flocking on top of `skinned_herd`, sharing the palette with synchronized phases (airborne flapping in unison is intentional). 25 bird species migrated from the Low Poly Bird Ultimate Pack, each a single draw call.
Per-instance custom data means a walking Boar, a running Boar, an idle Boar, and an attacking Boar all share the same baked palette — they just point at different rows. The renderer groups by type, not by state. One palette, one draw call, any number of states.
## Two bugs we shipped and fixed
The module had data-plane doctests from day one — round-trip pose get/set, dirty tracking, size clamping, AABB, column-major layout. All green. Then we put it on screen and two things were wrong.
**Bug 1: Shader compile failure.** The default skinning shader compared `TANGENT` as `vec4`. Godot 4 exposes it as `vec3`. Fixed in one line, added `albedo_tex` uniform so herds texture out of the box.
**Bug 2: Bone matrices stored transposed.** The initial data plane wrote basis rows (standard Godot `Transform3D.basis` is row-major), but the shader reads `mat4(c0,c1,c2,c3)` as columns. Every bone matrix was transposed — the mesh crumpled. Not a scale bug, not an orientation bug — a layout mismatch. Fixed by storing column-major, with a doctest to prevent regression.
The lesson: doctests catch logic. Rendering catches truth. You need both.
## The engine change
The module is 40 lines of shader code and ~500 lines of C++ in the engine's `modules/agent_skinned/`. The critical detail is in the shader: the bone-matrix texture is indexed by a **pose slot** computed from `INSTANCE_CUSTOM`, not by `INSTANCE_ID`. This is what decouples the palette from the instance count — the texture stores animation frames, the MultiMesh stores instance transforms, and the shader bridges them.
Engine version: **4.6.5.**
No C# wrapper is generated — instantiate from GDScript via `ClassDB.instantiate()` and call the bound methods. The binding surface is small and stable. See `ariki-game/scenes/animals/skinned_herd.gd` for the reference backend.
## The production pipeline
The `migrate_animals.py` tool converts polyperfect FBX packs to game-ready GLBs — imports, cleans hierarchy, rebuilds named NLA clips from frame ranges, strips duplicate meshes, bakes into the flat `assets/models/glbs/` directory. Each animal gets a catalog entry in `animals_catalog.json` with clip metadata, default state mapping, and an `animSpeedRef` for foot-sync.
At runtime, `AnimalHerdRenderer` spawns one `skinned_herd` per animal type. The herd bakes the palette from the catalog GLB's clips. `AnimalAnimationLogic` maps sim FSM states to clip keywords (attack → "attack"/"bite", flee → "run"/"gallop", wander → "walk"). The renderer lerps positions between sim ticks for smooth motion and writes per-instance custom data each frame. Zero per-frame CPU on the animation path.
## Where we stand vs the industry
The bone-matrix palette technique is the same architecture used by Assassin's Creed Unity, Total War: Warhammer, and Hitman for their crowd systems. We're using the same core idea, in a Godot fork, with smaller VRAM — our low-poly animals keep textures tiny.
The platform supports three tiers by distance, all driven by the same `(clip, count, speed, phase)` packet:
- **Crowd tier (palette)** — baked poses, GPU-driven, zero CPU. Thousands of agents.
- **Hero tier (real rigs)** — `AnimationTree` + `SkeletonIK3D` + `PhysicalBone3D` for the nearest few. Smooth gait blends, foot-lock, look-at, ragdoll.
- **Impostor tier (2D billboards)** — sprite atlas indexed by view-angle and animation-frame. For very far agents.
One abstraction, three detail levels. The same code that drives 30 animals today will drive thousands of colonists at launch.
## What's deliberately not here
- **No C# wrapper.** Instantiate from GDScript via `ClassDB.instantiate()` — the binding surface is small and stable.
- **No automatic `AnimationPlayer` integration.** You drive poses. We give you the texture. Freedom to animate however you want.
- **No GPU occlusion or LOD.** That's the game's job. The engine provides the tool; the game decides what to draw.
- **No automatic `AnimationPlayer` integration.** You drive poses at bake time. We give you the texture. Freedom to animate however you want.
- **No GPU occlusion culling.** That's the game's job. The engine provides the tool; the game decides what to draw.
## Get the build
Pre-built editor binaries with `agent_skinned` baked in — no engine compile required. The game's `animal_perf_test.tscn` lets you toggle 10 / 100 / 1000 animals and read live FPS:
Pre-built editor binaries with `agent_skinned` and the GPU-driven palette baked in — no engine compile required. The game's `animal_perf_test.tscn` lets you spawn 10/100/1,000/10,000 animals and read live FPS:
| Platform | Binary | Engine commit |
|----------|--------|---------------|
| **macOS ARM64** | [`tinqs.macos.editor.arm64.mono`](https://tinqs.com/tinqs/builds/media/branch/main/engine/macos-arm64/tinqs.macos.editor.arm64.mono) | `4fe1323` (4.6.4, Xcode 26.3) |
| **Windows x64** | [`tinqs.windows.editor.x86_64.mono.exe`](https://tinqs.com/tinqs/builds/media/branch/main/engine/windows-x64/tinqs.windows.editor.x86_64.mono.exe) | `64fb5cc` (4.6.4, MSVC 2022) |
| Platform | Binary |
|----------|--------|
| **macOS ARM64** | [`tinqs.macos.editor.arm64.mono`](https://tinqs.com/tinqs/builds/media/branch/main/engine/macos-arm64/tinqs.macos.editor.arm64.mono) |
| **Windows x64** | [`tinqs.windows.editor.x86_64.mono.exe`](https://tinqs.com/tinqs/builds/media/branch/main/engine/windows-x64/tinqs.windows.editor.x86_64.mono.exe) |
All builds live in the public [`tinqs/builds`](https://tinqs.com/tinqs/builds) repo — engine source is private, but the binaries are yours. See [`manifest.json`](https://tinqs.com/tinqs/builds/src/branch/main/manifest.json) for checksums and build details.
All builds at [`tinqs/builds`](https://tinqs.com/tinqs/builds) — engine source is private, but the binaries are yours. See [`manifest.json`](https://tinqs.com/tinqs/builds/src/branch/main/manifest.json) for checksums and build details.
The engine source lives in [`tinqs/engine`](https://tinqs.com/tinqs/engine) (private). Module docs: `modules/agent_skinned/README.md` and `.agents/wiki/agent-skinned-gpu-herd.md`.