2nd/10_Wiki/Topics/DevOps_and_Security/SkinnedMesh.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-skinnedmesh	SkinnedMesh	10_Wiki/Topics	verified	self	P-Reinforce-AUTO-1189F7 Skinned Mesh GPU Skinning	none	A	0.93	applied	3d graphics animation threejs webgl		2026-05-10	pending	language framework TypeScript Three.js / WebGL2

SkinnedMesh

매 한 줄

"매 mesh 의 vertex 가 매 bone weight 에 의해 deformed — single draw call 의 articulated character". 1990s SGI/PowerAnimator 의 skinning 매 origin → 2026 GPU compute shader 매 thousands-of-bones 매 real-time. Three.js SkinnedMesh 매 WebGPU compute path 매 standard.

매 핵심

매 구성 요소

• Mesh geometry: vertex position + skin index (4 bones/vertex 매 typical) + skin weight.
• Skeleton: bone hierarchy + bind matrix (rest pose inverse).
• Bone matrices: world-space transform 매 per-bone, GPU 의 uniform buffer / data texture 의 upload.

매 GPU pipeline

• Vertex shader 의 매 vertex 의 bone matrices 의 weighted blend 의 적용 → world-space pos.
• Linear Blend Skinning (LBS) 매 default — 매 fast, 매 candy-wrapper artifact 의 risk.
• Dual Quaternion Skinning (DQS) 매 alternative — 매 volume-preserving, 매 ~1.3x cost.

매 응용

1. Character animation (게임, AR/VR avatar).
2. Cloth/soft-body 의 partial rigging.
3. Procedural creature 의 spline-driven bones.

💻 패턴

Three.js 매 SkinnedMesh 생성

import * as THREE from 'three';

const geometry = new THREE.CylinderGeometry(0.3, 0.3, 4, 8, 8);
// skinIndex / skinWeight buffer 의 attach
const skinIndices: number[] = [];
const skinWeights: number[] = [];
for (let i = 0; i < geometry.attributes.position.count; i++) {
  const y = geometry.attributes.position.getY(i) + 2; // 0..4
  const skinIndex = Math.floor(y);
  const skinWeight = y - skinIndex;
  skinIndices.push(skinIndex, skinIndex + 1, 0, 0);
  skinWeights.push(1 - skinWeight, skinWeight, 0, 0);
}
geometry.setAttribute('skinIndex', new THREE.Uint16BufferAttribute(skinIndices, 4));
geometry.setAttribute('skinWeight', new THREE.Float32BufferAttribute(skinWeights, 4));

// Bone hierarchy
const bones: THREE.Bone[] = [];
for (let i = 0; i <= 4; i++) {
  const b = new THREE.Bone();
  b.position.y = i === 0 ? -2 : 1;
  if (i > 0) bones[i - 1].add(b);
  bones.push(b);
}
const skeleton = new THREE.Skeleton(bones);

const mesh = new THREE.SkinnedMesh(geometry, new THREE.MeshStandardMaterial({ skinning: true } as any));
mesh.add(bones[0]);
mesh.bind(skeleton);

매 GLTF asset 매 load

import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js';
const loader = new GLTFLoader();
const gltf = await loader.loadAsync('/models/character.glb');
const skinned = gltf.scene.getObjectByProperty('isSkinnedMesh', true) as THREE.SkinnedMesh;
const mixer = new THREE.AnimationMixer(skinned);
const action = mixer.clipAction(gltf.animations[0]);
action.play();

매 GPU instancing 매 SkinnedMesh — BatchedMesh + skeleton texture

// 2026 Three.js r170+ 의 InstancedSkinnedMesh
const inst = new THREE.InstancedSkinnedMesh(geometry, material, 1000);
inst.boundingSphere = new THREE.Sphere(new THREE.Vector3(), 5);
// 매 per-instance 의 별도 skeleton bone matrix texture 의 upload

매 LBS 매 vertex shader (GLSL)

mat4 skinMatrix =
  skinWeight.x * boneMatrix(skinIndex.x) +
  skinWeight.y * boneMatrix(skinIndex.y) +
  skinWeight.z * boneMatrix(skinIndex.z) +
  skinWeight.w * boneMatrix(skinIndex.w);
vec4 skinned = skinMatrix * vec4(position, 1.0);
gl_Position = projectionMatrix * modelViewMatrix * skinned;

매 bone matrix 의 DataTexture 매 upload (large skeleton)

const boneTexture = new THREE.DataTexture(
  new Float32Array(bones.length * 16),
  bones.length * 4, 1, THREE.RGBAFormat, THREE.FloatType,
);
skeleton.boneTexture = boneTexture; // automatically updated

매 결정 기준

상황	Approach
Character < 256 bones, 단일 instance	uniform array bone matrices
Character ≥ 256 bones, 매 mobile 의 uniform limit 의 hit	boneTexture (DataTexture)
매 large crowd (100+ chars)	InstancedSkinnedMesh + 매 per-instance skeleton texture
매 volume-preserving 의 deformation 의 필요	DQS or 매 corrective shape keys
매 simple twist 매 only	Bend modifier or 매 spline-IK 의 fallback

기본값: GLTF + Three.js SkinnedMesh + LBS + boneTexture 의 mobile path.

🔗 Graph

• 부모: Three.js · WebGL 20
• Adjacent: BufferGeometry · BatchedMesh 및 InstancedMesh 성능 벤치마크

🤖 LLM 활용

언제: GLTF rigged character 의 import, 매 bone weight 의 painting 의 review, 매 skinning artifact 의 debug. 언제 X: 매 static prop 의 transform — Mesh + matrix update 의 더 cheap.

❌ 안티패턴

• 매 vertex 별 매 8+ bone weight: GPU 매 4-weight 의 standard. Excess bones 의 normalize + drop low-weight 의 필요.
• 매 frame 별 skeleton.update() 의 manual call: Three.js 매 already 매 auto. Redundant 의 cost.
• 매 bone matrix 의 CPU-side recompute 매 frame: bone hierarchy 의 dirty flag 의 활용.
• SkinnedMesh.clone() 의 후 매 same skeleton 의 share: 매 separate Skeleton.clone() 의 필요 — else 매 모든 instances 매 같은 pose.

🧪 검증 / 중복

• Verified (Three.js docs r170, Khronos glTF 2.0 spec, Real-Time Rendering 4e Ch.4).
• 신뢰도 A.
• 중복 risk: GPU Skinning (alias).

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — SkinnedMesh의 components, GPU pipeline, instancing 정리