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<title>GPU-Skinned Herds: One Draw Call for 1,000 Animated Characters in Godot — Tinqs Blog</title>
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<meta name="description" content="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.">
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"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."
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<!-- POST -->
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<article class="post">
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<a href="/blog/" class="post__back">← All Posts</a>
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<span class="post__date">14 June 2026</span>
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<h1 class="post__title">GPU-Skinned Herds: One Draw Call for 1,000 Animated Characters in Godot</h1>
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<p class="post__lead">Godot gives you one <code>Skeleton3D</code> per character. Want 200 animals in a herd? That's 200 skeleton nodes, 200 draw calls, and 200 <code>AnimationPlayer</code> ticks every frame. Want 1,000? Now you're measuring in seconds per frame, not frames per second.</p>
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<div class="post__body">
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<p>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.</p>
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<h2>Why the engine needs to change</h2>
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<p>The standard Godot approach — one <code>Skeleton3D</code> + one <code>MeshInstance3D</code> per character — works for a handful of animated entities. It breaks down hard at crowd scale:</p>
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<ul>
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<li><strong>CPU bone transforms.</strong> Computing <code>global_pose</code> for 200 skeletons × 100 bones each = 20,000 matrix multiplies per frame, all on the main thread.</li>
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<li><strong>Draw call explosion.</strong> Each <code>MeshInstance3D</code> is its own draw call. Even with MultiMesh, there's no built-in path for skinned meshes — <code>MultiMeshInstance3D</code> only handles static geometry.</li>
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<li><strong>AnimationPlayer sprawl.</strong> Each skeleton needs its own <code>AnimationPlayer</code> and its own <code>process()</code> tick.</li>
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</ul>
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<p>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.</p>
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<p>What we need is simpler: <strong>share the skeleton, drive per-instance poses from a single animation, batch the draw call.</strong> That's what <code>agent_skinned</code> does.</p>
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<h2>How it works: two classes, one texture</h2>
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<p>The module lives in <code>modules/agent_skinned/</code> inside <a href="https://tinqs.com/tinqs/engine" style="color: var(--c-lime);">Tinqs Engine</a>. Two classes, one job:</p>
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<h3><code>MultiSkinnedMeshInstance3D</code> — the data plane</h3>
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<p>Holds the CPU-side bone matrices. Allocates an <code>ImageTexture</code> of size <code>[4 × max_bones, max_instances]</code> in RGBA32F — each texel is one column of a 4×4 bone matrix. For a 130-bone crocodile with 256 instances:</p>
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<pre><code>Texture: 520 × 256 RGBA32F ≈ 2 MB</code></pre>
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<p>That's the entire pose state for 256 animated crocodiles in a single GPU texture. The API is simple:</p>
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<pre><code class="language-gdscript">var data := MultiSkinnedMeshInstance3D.new()
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data.set_mesh(crocodile_mesh)
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data.set_skeleton(skeleton) # rest pose + bone hierarchy
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data.set_max_instances(256)
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data.set_max_bones(130)
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# Each frame: push poses from the animated skeleton
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for instance in herd_positions:
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data.set_instance_pose_bones(instance.id, bone_transforms)
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data.update() # upload only dirty instances, not the whole texture</code></pre>
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<h3><code>MultiSkinnedInstance3D</code> — the renderer</h3>
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<p>A <code>MultiMeshInstance3D</code> subclass. Set its multimesh with the skinned mesh and instance transforms, point it at the data plane, call <code>refresh()</code> — it uploads the bone texture into the shader material's <code>bone_matrices_tex</code> uniform and the mesh is drawn in one call.</p>
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<p>The shader does 4-bone linear-blend skinning on the GPU:</p>
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<pre><code class="language-glsl">mat4 get_bone(int b) {
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return mat4(
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texelFetch(bone_matrices_tex, ivec2(b * 4 + 0, INSTANCE_ID), 0),
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texelFetch(bone_matrices_tex, ivec2(b * 4 + 1, INSTANCE_ID), 0),
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texelFetch(bone_matrices_tex, ivec2(b * 4 + 2, INSTANCE_ID), 0),
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texelFetch(bone_matrices_tex, ivec2(b * 4 + 3, INSTANCE_ID), 0)
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);
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}</code></pre>
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<p><code>INSTANCE_ID</code> 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.</p>
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<h2>Two bugs we shipped and fixed</h2>
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<p>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.</p>
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<p><strong>Bug 1: Shader compile failure.</strong> The default skinning shader compared <code>TANGENT</code> as <code>vec4</code>. Godot 4 exposes it as <code>vec3</code>. Fixed in one line, added <code>albedo_tex</code> uniform so herds texture out of the box.</p>
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<p><strong>Bug 2: Bone matrices stored transposed.</strong> The data plane wrote basis rows (standard Godot <code>Transform3D.basis</code> 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.</p>
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<p>The lesson: doctests catch logic. Rendering catches truth. You need both.</p>
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<h2>What's driving it</h2>
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<p>In <a href="https://www.arikigame.com" style="color: var(--c-lime);">Ariki</a>, the sim tracks animal migration across a 12km archipelago. <code>AnimalHerdRenderer.cs</code> groups sim <code>ViewerState.animals</code> by type, feeds positions to <code>skinned_herd.gd</code> (a reusable per-type herd backend), which drives the renderer. One <code>AnimationPlayer</code> animates a single driver skeleton; poses propagate to every instance.</p>
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<p>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.</p>
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<h2>What's deliberately not here</h2>
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<ul>
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<li><strong>No C# wrapper.</strong> Instantiate from GDScript via <code>ClassDB.instantiate()</code> — the binding surface is small and stable.</li>
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<li><strong>No automatic <code>AnimationPlayer</code> integration.</strong> You drive poses. We give you the texture. Freedom to animate however you want.</li>
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<li><strong>No GPU occlusion or LOD.</strong> That's the game's job. The engine provides the tool; the game decides what to draw.</li>
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</ul>
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<h2>Get the build</h2>
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<p>Pre-built editor binaries with <code>agent_skinned</code> baked in — no engine compile required. The game's <code>animal_perf_test.tscn</code> lets you toggle 10 / 100 / 1000 animals and read live FPS:</p>
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<p>| Platform | Binary | Engine commit |</p>
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<p>|———-|——–|—————|</p>
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<p>| <strong>macOS ARM64</strong> | <a href="https://tinqs.com/tinqs/builds/media/branch/main/engine/macos-arm64/tinqs.macos.editor.arm64.mono" style="color: var(--c-lime);"><code>tinqs.macos.editor.arm64.mono</code></a> | <code>4fe1323</code> (4.6.4, Xcode 26.3) |</p>
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<p>| <strong>Windows x64</strong> | <a href="https://tinqs.com/tinqs/builds/media/branch/main/engine/windows-x64/tinqs.windows.editor.x86_64.mono.exe" style="color: var(--c-lime);"><code>tinqs.windows.editor.x86_64.mono.exe</code></a> | <code>64fb5cc</code> (4.6.4, MSVC 2022) |</p>
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<p>All builds live in the public <a href="https://tinqs.com/tinqs/builds" style="color: var(--c-lime);"><code>tinqs/builds</code></a> repo — engine source is private, but the binaries are yours. See <a href="https://tinqs.com/tinqs/builds/src/branch/main/manifest.json" style="color: var(--c-lime);"><code>manifest.json</code></a> for checksums and build details.</p>
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<p>The engine source lives in <a href="https://tinqs.com/tinqs/engine" style="color: var(--c-lime);"><code>tinqs/engine</code></a> (private). Module docs: <code>modules/agent_skinned/README.md</code> and <code>.agents/wiki/agent-skinned-gpu-herd.md</code>.</p>
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<hr>
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<p><strong>Related:</strong> <a href="fork-dont-build" style="color: var(--c-lime);">Fork, Don't Build</a> — why we modify existing platforms instead of building new ones. <a href="godot-optimisation" style="color: var(--c-lime);">Streaming a 12km Archipelago in Godot 4</a> — the terrain and vegetation streaming layers that work alongside this.</p>
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</div>
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<div class="post__author">
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<div class="post__author-avatar">OB</div>
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<div class="post__author-info">
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<span class="post__author-name">Ozan Bozkurt</span><br>
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CTO & Developer, Tinqs
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</div>
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</div>
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</article>
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