Add orb scene

Author: gkjohnson

example/utils/MaterialOrbLoader.js

@@ -0,0 +1,61 @@
+import { RectAreaLight } from 'three';
+import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js';
+
+const ORB_SCENE_URL = 'https://raw.githubusercontent.com/gkjohnson/3d-demo-data/main/models/usd-shader-ball/usd-shaderball-scene.glb';
+
+function assignWatts( light, watts ) {
+
+	// https://github.com/will-ca/glTF-Blender-IO/blob/af9e7f06508a95425b05e485fa83681b268bbdfc/addons/io_scene_gltf2/blender/exp/gltf2_blender_gather_lights.py#L92-L97
+	const PBR_WATTS_TO_LUMENS = 683;
+	const area = light.width * light.height;
+	const lumens = PBR_WATTS_TO_LUMENS * watts;
+	light.intensity = lumens / ( area * 4 * Math.PI );
+
+}
+
+export class MaterialOrbSceneLoader {
+
+	constructor( manager ) {
+
+		this.manager = manager;
+
+	}
+
+	loadAsync( url = ORB_SCENE_URL, ...rest ) {
+
+		return new GLTFLoader( this.manager )
+			.loadAsync( url, ...rest )
+			.then( gltf => {
+
+				const {
+					scene,
+					lights,
+					cameras,
+				} = gltf;
+
+				const leftLight = new RectAreaLight( 0xffffff, 1, 15, 15 );
+				assignWatts( leftLight, 6327.84 );
+				scene.getObjectByName( 'light' ).add( leftLight );
+
+				for ( let i = 0; i < 4; i ++ ) {
+
+					const light = new RectAreaLight( 0xffffff, 1, 24.36, 24.36 );
+					assignWatts( leftLight, 11185.5 );
+					scene.getObjectByName( 'light' + i ).add( light );
+
+				}
+
+				return {
+
+					material: scene.getObjectByName( 'material_surface' ).material,
+					cameras,
+					lights,
+					scene,
+
+				};
+
+			} );
+
+	}
+
+}