---
id: wiki-2026-0508-ifcjs
title: IFCjs
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [That Open Engine, web-ifc, Three.js IFC, BIM viewer]
duplicate_of: none
source_trust_level: A
confidence_score: 0.85
verification_status: applied
tags: [bim, ifc, web, three-js, aec, webgl]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: typescript
  framework: web-ifc-three
---

# IFCjs

## 매 한 줄
> **"매 browser 안의 IFC (Industry Foundation Classes) reader/viewer — 매 BIM 데이터를 매 Three.js scene 으로"**. IFCjs (현재 매 "That Open Engine" 으로 rebrand) 는 매 web-ifc (WASM IFC parser) + 매 Three.js based 매 viewer 의 묶음. 매 AEC (Architecture/Engineering/Construction) 매 web 진입의 standard. 매 2026 현재 매 OpenBIM 운동 의 매 핵심 component.

## 매 핵심

### 매 stack 의 layer
- **web-ifc (C++ → WASM)**: 매 IFC2x3 / IFC4 / IFC4x3 STEP file 의 매 streaming parser.
- **web-ifc-three** (legacy): 매 Three.js mesh 로 변환, property set 추출.
- **@thatopen/components**: 매 modern (2024+) — Three.js 위 UI/tool framework.
- **@thatopen/ui**: 매 web-component 기반 panel/grid/property card.

### 매 IFC 의 본질
- **STEP physical file**: ASCII textual, 매 entity reference graph (`#1=IFCBUILDING(...)`).
- **EXPRESS schema**: 매 IFC4 는 매 1700+ entity types.
- **Geometric representations**: 매 boundary representation, swept solid, CSG, tessellated mesh.
- **Property sets (Psets)**: 매 entity 별 매 metadata bag.

### 매 web vs desktop trade-off
- 매 desktop (Revit, ArchiCAD): full editing, plugin ecosystem.
- 매 web (IFCjs/ThatOpen): zero-install, collaborative review, lightweight viewer.
- 매 hybrid: 매 export IFC from Revit → web viewer.

## 💻 패턴

### Basic IFC viewer (ThatOpen Components 2024+)
```ts
import * as OBC from '@thatopen/components';
import * as THREE from 'three';

const components = new OBC.Components();
const worlds = components.get(OBC.Worlds);
const world = worlds.create<
  OBC.SimpleScene, OBC.SimpleCamera, OBC.SimpleRenderer
>();

const container = document.getElementById('app')!;
world.scene  = new OBC.SimpleScene(components);
world.renderer = new OBC.SimpleRenderer(components, container);
world.camera = new OBC.SimpleCamera(components);
world.scene.setup();

components.init();

const fragments = components.get(OBC.FragmentsManager);
const ifcLoader = components.get(OBC.IfcLoader);
await ifcLoader.setup();

const file = await fetch('/models/building.ifc');
const buffer = new Uint8Array(await file.arrayBuffer());
const model = await ifcLoader.load(buffer);
world.scene.three.add(model);
```

### Property extraction via web-ifc directly
```ts
import { IfcAPI, IFCWALLSTANDARDCASE } from 'web-ifc';

const api = new IfcAPI();
api.SetWasmPath('/wasm/');
await api.Init();

const data = new Uint8Array(await fetch('/m.ifc').then(r => r.arrayBuffer()));
const modelID = api.OpenModel(data);

const wallIDs = api.GetLineIDsWithType(modelID, IFCWALLSTANDARDCASE);
for (let i = 0; i < wallIDs.size(); i++) {
  const id = wallIDs.get(i);
  const wall = api.GetLine(modelID, id, true); // recursive expand refs
  console.log(wall.GlobalId.value, wall.Name?.value);
}
api.CloseModel(modelID);
```

### Picking + property panel
```ts
const highlighter = components.get(OBC.Highlighter);
highlighter.setup({ world });

highlighter.events.select.onHighlight.add(async (fragmentMap) => {
  const indexer = components.get(OBC.IfcRelationsIndexer);
  for (const fragId in fragmentMap) {
    const expressIDs = [...fragmentMap[fragId]];
    for (const id of expressIDs) {
      const psets = await indexer.getEntityRelations(model, id, 'IsDefinedBy');
      console.log('expressID', id, 'psets', psets);
    }
  }
});
```

### Convert IFC → fragments (compact binary)
```ts
// fragments are ThatOpen's optimized binary mesh format
const fragmentManager = components.get(OBC.FragmentsManager);
const buffer = fragmentManager.export(model);
await fetch('/upload', { method: 'POST', body: buffer });
```

### Server-side conversion (Node + web-ifc-node)
```ts
import { IfcAPI } from 'web-ifc/web-ifc-api-node';
import { promises as fs } from 'fs';

const api = new IfcAPI();
api.SetWasmPath('node_modules/web-ifc/');
await api.Init();
const buf = await fs.readFile('input.ifc');
const id = api.OpenModel(buf);
const flatMesh = api.LoadAllGeometry(id);
// ... extract triangles, write to glTF
```

### BIM clash detection (rough proxy)
```ts
import { Box3, Vector3 } from 'three';

function findClashes(meshes: THREE.Mesh[]) {
  const boxes = meshes.map(m => {
    const b = new Box3().setFromObject(m);
    return { box: b, mesh: m };
  });
  const clashes: [THREE.Mesh, THREE.Mesh][] = [];
  for (let i = 0; i < boxes.length; i++)
    for (let j = i + 1; j < boxes.length; j++)
      if (boxes[i].box.intersectsBox(boxes[j].box))
        clashes.push([boxes[i].mesh, boxes[j].mesh]);
  return clashes;
}
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Web-only IFC viewer | ThatOpen Components |
| Server-side IFC parsing | web-ifc-node |
| Property extraction only | web-ifc API directly |
| Heavy editing | desktop (Revit) export |
| Massive models (>1GB) | fragments format + tile streaming |
| Clash detection on web | use AABB pre-filter + GPU mesh-mesh |

**기본값**: 매 modern AEC web app — ThatOpen Components + fragments.

## 🔗 Graph
- 부모: [[BIM]] · [[3D Web Viewer]]
- 변형: [[Bimsync]] · [[Speckle]] · [[Forge / APS]]
- 응용: [[Digital Twin]] · [[Construction Management]] · [[Clash Detection]]
- Adjacent: [[Three.js]] · [[glTF]] · [[USD]] · [[OpenBIM]]

## 🤖 LLM 활용
**언제**: IFC entity 의 mapping 설명 (IFC → glTF), property set 매 자연어 query, 매 UI panel scaffold.
**언제 X**: 매 large IFC parsing performance 최적화 — 매 measure 매 직접.

## ❌ 안티패턴
- **Loading 1GB IFC into browser memory directly**: 매 OOM — 매 fragments + streaming 사용.
- **Recursive GetLine on every entity**: 매 N² — 매 IfcRelationsIndexer 사용.
- **Treating IFC as glTF**: 매 IFC 는 매 graph + semantics, 매 mesh-only X.
- **No coordinate system handling**: 매 IFC 의 IfcSite localPlacement 무시 → 매 wrong global pos.
- **Missing wasm path**: 매 web-ifc 의 매 WASM file 의 매 hosting failure — `SetWasmPath` 명시.

## 🧪 검증 / 중복
- Verified (ThatOpen Engine docs 2026, web-ifc GitHub).
- 신뢰도 A.

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — IFC stack + ThatOpen Components patterns |
