2nd/10_Wiki/Topics/Frontend/WebGL 모바일 GPU 성능 관리.md

---
id: wiki-2026-0508-webgl-모바일-gpu-성능-관리
title: WebGL 모바일 GPU 성능 관리
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [WebGL Mobile Performance, Mobile GPU WebGL]
duplicate_of: none
source_trust_level: A
confidence_score: 0.9
verification_status: applied
tags: [webgl, mobile, gpu, performance, thermal]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: JavaScript/GLSL
  framework: WebGL2 / Three.js
---

# WebGL 모바일 GPU 성능 관리

## 매 한 줄
> **"매 thermal throttle 의 적 — fillrate 의 절약"**. Mobile GPU (Adreno / Mali / Apple) 매 tile-based deferred 의 fillrate / bandwidth bound — overdraw + texture size + shader complexity 매 dominant cost. 2026 modern stack 매 WebGPU 매 advanced — WebGL2 매 still ubiquitous fallback.

## 매 핵심

### 매 mobile GPU 차이
- **TBDR (Tile-Based Deferred Rendering)**: Mali / Apple / PowerVR — early-Z + tile cache.
- **IMR (Immediate Mode)**: desktop NVIDIA / AMD — overdraw 매 expensive.
- **Adreno**: hybrid — flexrender (tile + immediate).
- **Bandwidth bound**: mobile DRAM 매 desktop 의 1/5 — texture size 의 major impact.
- **Thermal**: sustained GPU load → throttle → 30-50% perf drop in 30-60s.

### 매 bottleneck 식별
- **Fragment-bound**: fragment shader complexity / overdraw — resolution down / shader simplify.
- **Vertex-bound**: triangle count — LOD / cull.
- **Bandwidth-bound**: texture size + framebuffer — compress / lower precision.
- **Draw call-bound**: state changes — batch / instance.

### 매 응용
1. **Mobile web games**: PlayCanvas / Three.js — 60fps target on mid-tier device.
2. **AR / VR web** (WebXR): Quest browser / iOS Safari WebXR — 72-90fps strict.
3. **Map / data viz**: Mapbox GL — millions of features on phone.
4. **Product 3D viewer**: e-commerce — fast load + smooth orbit.

## 💻 패턴

### Resolution scaling 매 dynamic
```js
let scale = 1.0;
let lastFrameTime = performance.now();
function frame(now) {
  const dt = now - lastFrameTime; lastFrameTime = now;
  if (dt > 22 && scale > 0.5) scale -= 0.05; // <45fps → downscale
  else if (dt < 14 && scale < 1.0) scale += 0.02;
  const w = Math.floor(canvas.clientWidth * devicePixelRatio * scale);
  const h = Math.floor(canvas.clientHeight * devicePixelRatio * scale);
  if (canvas.width !== w) { canvas.width = w; canvas.height = h; gl.viewport(0,0,w,h); }
  render();
  requestAnimationFrame(frame);
}
```

### Texture compression 매 KTX2 / Basis
```js
import { KTX2Loader } from 'three/addons/loaders/KTX2Loader.js';
const loader = new KTX2Loader()
  .setTranscoderPath('/basis/')
  .detectSupport(renderer);
loader.load('texture.ktx2', (tex) => { /* ASTC / ETC2 / BC7 transcode 매 device */ });
// 매 mobile 의 ASTC — 매 4-8x smaller VRAM + bandwidth
```

### Overdraw 매 줄임
```js
// 매 sort opaque front-to-back (early-Z reject)
opaque.sort((a, b) => a.distanceToCamera - b.distanceToCamera);

// 매 transparent back-to-front (correct blending)
transparent.sort((a, b) => b.distanceToCamera - a.distanceToCamera);

// 매 alpha-test 의 alpha-blend 보다 prefer (TBDR-friendly)
material.alphaTest = 0.5; material.transparent = false;
```

### Mipmap 매 always
```js
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
gl.generateMipmap(gl.TEXTURE_2D);
// 매 minified texture 의 cache hit + bandwidth 의 1/3
```

### LOD 매 distance-based
```js
const lod = new THREE.LOD();
lod.addLevel(highMesh, 0);    // 0-10m: 50k tris
lod.addLevel(midMesh, 10);    // 10-30m: 10k tris
lod.addLevel(lowMesh, 30);    // 30m+: 2k tris
scene.add(lod);
```

### Shader precision 매 mediump
```glsl
#version 300 es
precision mediump float; // 매 16-bit on mobile — 매 highp 보다 2x throughput
in vec2 vUv;
uniform sampler2D map;
out vec4 fragColor;
void main() { fragColor = texture(map, vUv); }
```

### Thermal-aware quality scaling
```js
// 매 thermal API (limited) + battery + perf observer
async function detectTier() {
  const battery = await navigator.getBattery?.();
  const memory = navigator.deviceMemory ?? 4;
  const cores = navigator.hardwareConcurrency ?? 4;
  if (memory <= 2 || cores <= 4) return 'low';
  if (memory <= 4) return 'mid';
  return 'high';
}
const tier = await detectTier();
const cfg = { low: { msaa: 0, shadows: false, dpr: 1 }, mid: { msaa: 2, shadows: true, dpr: 1.5 }, high: { msaa: 4, shadows: true, dpr: 2 } }[tier];
```

### Disable expensive features on mobile
```js
const isMobile = /Mobi|Android|iPhone/.test(navigator.userAgent);
renderer.shadowMap.enabled = !isMobile;
renderer.toneMapping = isMobile ? THREE.NoToneMapping : THREE.ACESFilmicToneMapping;
postProcessing.enabled = !isMobile; // bloom / SSAO 매 expensive
```

### Instanced rendering 매 thousands
```js
const mesh = new THREE.InstancedMesh(geometry, material, 5000);
for (let i = 0; i < 5000; i++) {
  mat.setPosition(randomPos());
  mesh.setMatrixAt(i, mat);
}
// 매 1 draw call 매 5k objects — mobile 의 huge win
```

## 매 결정 기준
| 증상 | 원인 | 처방 |
|---|---|---|
| Frame time spike | Overdraw | Front-to-back sort + alphaTest |
| Sustained slowdown | Thermal | Resolution scale + reduce shader |
| Memory OOM | Texture VRAM | KTX2 ASTC + mipmap + atlas |
| Stutter | GC / draw calls | Instance + pool |
| Low FPS on Adreno | Shader complexity | mediump + simplify |

**기본값**: WebGL2 + KTX2 textures + LOD + dynamic resolution + mediump shaders + InstancedMesh.

## 🔗 Graph
- 부모: [[WebGL API]]
- 변형: [[Threejs WebGPURenderer]] · [[Threejs WebGPURenderer|WebGL Optimization]]
- 응용: [[Threejs]] · [[WebXR]]
- Adjacent: [[KTX2]] · [[Basis Universal]]

## 🤖 LLM 활용
**언제**: mobile-targeted WebGL app — 60fps 의 mid-tier device 의 hold / thermal throttle 의 prevent.
**언제 X**: desktop-only / WebGPU available 매 flagship — WebGPU compute path 매 better.

## ❌ 안티패턴
- **`devicePixelRatio` 의 fixed**: 매 retina 의 4x fragments — clamp 1.5-2.
- **Uncompressed PNG**: 매 mobile VRAM 의 폭주 — KTX2 / Basis 의 사용.
- **Real-time shadows on low-end**: 매 30%+ frame budget — bake / disable.
- **Postprocessing on mobile**: bloom / SSAO 매 fillrate killer — disable.
- **No LOD**: distant 50k-tri mesh 매 vertex bound — LOD.
- **`highp` everywhere**: precision 매 mediump 의 충분 (color / UV).

## 🧪 검증 / 중복
- Verified (Khronos WebGL spec / Arm Mali best practices / Apple Metal docs).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — TBDR, KTX2, LOD, dynamic resolution, thermal awareness |