Grounded Skybox (#27448)

* initial change * mrdoob approves * updated example * update screenshot
mrdoob · Dec 28, 2023 · 36f9019 · 36f9019
1 parent dfbee3c
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diff --git a/examples/jsm/objects/GroundProjectedSkybox.js b/examples/jsm/objects/GroundProjectedSkybox.js
diff --git a/examples/jsm/objects/GroundedSkybox.js b/examples/jsm/objects/GroundedSkybox.js
@@ -0,0 +1,49 @@
+import { BackSide, Mesh, MeshBasicMaterial, SphereGeometry, Vector3 } from 'three';
+
+/**
+ * A ground-projected skybox. The height is how far the camera that took the photo was above the ground - 
+ * a larger value will magnify the downward part of the image. By default the object is centered at the camera, 
+ * so it is often helpful to set skybox.position.y = height to put the ground at the origin. Set the radius 
+ * large enough to ensure your user's camera stays inside.
+ */
+
+class GroundedSkybox extends Mesh {
+
+	constructor( map, height, radius, resolution = 128 ) {
+
+		if ( height <= 0 || radius <= 0 || resolution <= 0 ) {
+
+			throw new Error( 'GroundedSkybox height, radius, and resolution must be positive.' );
+
+		}
+
+		const geometry = new SphereGeometry( radius, 2 * resolution, resolution );
+
+		const pos = geometry.getAttribute( 'position' );
+		const tmp = new Vector3();
+
+		for ( let i = 0; i < pos.count; ++ i ) {
+
+			tmp.fromBufferAttribute( pos, i );
+			if ( tmp.y < 0 ) {
+
+				// Smooth out the transition from flat floor to sphere:
+				const y1 = - height * 3 / 2;
+				const f =
+						tmp.y < y1 ? - height / tmp.y : ( 1 - tmp.y * tmp.y / ( 3 * y1 * y1 ) );
+				tmp.multiplyScalar( f );
+				tmp.toArray( pos.array, 3 * i );
+
+			}
+
+		}
+
+		pos.needsUpdate = true;
+
+		super( geometry, new MeshBasicMaterial( { map, side: BackSide } ) );
+
+	}
+
+}
+
+export { GroundedSkybox };
diff --git a/examples/screenshots/webgl_materials_envmaps_groundprojected.jpg b/examples/screenshots/webgl_materials_envmaps_groundprojected.jpg
diff --git a/examples/webgl_materials_envmaps_groundprojected.html b/examples/webgl_materials_envmaps_groundprojected.html
@@ -14,7 +14,7 @@
 	<body>
 		<div id="container"></div>
 		<div id="info">
-			<a href="https://threejs.org" target="_blank" rel="noopener">threejs</a> - Ground projected environment mapping. By <a href="https://twitter.com/CantBeFaraz" target="_blank" rel="noopener">Faraz Shaikh</a>.<br>
+			<a href="https://threejs.org" target="_blank" rel="noopener">threejs</a> - Ground projected environment mapping.<br>
 			Ferrari 458 Italia model by <a href="https://sketchfab.com/models/57bf6cc56931426e87494f554df1dab6" target="_blank" rel="noopener">vicent091036</a><br>
 			<a href="https://polyhaven.com/a/blouberg_sunrise_2" target="_blank" rel="noopener">Blouberg Sunrise 2</a> by <a href="https://gregzaal.com/" target="_blank" rel="noopener">Greg Zaal</a>
 		</div>
@@ -31,16 +31,15 @@
 		<script type="module">
 			import * as THREE from 'three';
 
-			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';
 			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
-			import { GroundProjectedSkybox } from 'three/addons/objects/GroundProjectedSkybox.js';
+			import { GroundedSkybox } from 'three/addons/objects/GroundedSkybox.js';
 			import { GLTFLoader } from 'three/addons/loaders/GLTFLoader.js';
 			import { DRACOLoader } from 'three/addons/loaders/DRACOLoader.js';
 			import { RGBELoader } from 'three/addons/loaders/RGBELoader.js';
 
 			const params = {
-				height: 20,
-				radius: 440
+				height: 15,
+				radius: 100
 			};
 
 			let camera, scene, renderer, skybox;
@@ -64,8 +63,8 @@
 				const envMap = await hdrLoader.loadAsync( 'textures/equirectangular/blouberg_sunrise_2_1k.hdr' );
 				envMap.mapping = THREE.EquirectangularReflectionMapping;
 
-				skybox = new GroundProjectedSkybox( envMap );
-				skybox.scale.setScalar( 100 );
+				skybox = new GroundedSkybox( envMap, params.height, params.radius );
+				skybox.position.y = params.height - 0.01;
 				scene.add( skybox );
 
 				scene.environment = envMap;
@@ -115,7 +114,6 @@
 						} )
 					);
 					mesh.rotation.x = - Math.PI / 2;
-					mesh.renderOrder = 2;
 					carModel.add( mesh );
 
 					scene.add( carModel );
@@ -142,12 +140,6 @@
 				controls.enablePan = false;
 				controls.update();
 
-				const gui = new GUI();
-				gui.add( params, 'height', 20, 50, 0.1 ).name( 'Skybox height' ).onChange( render );
-				gui.add( params, 'radius', 200, 600, 0.1 ).name( 'Skybox radius' ).onChange( render );
-
-				//
-
 				document.body.appendChild( renderer.domElement );
 				window.addEventListener( 'resize', onWindowResize );
 
@@ -168,9 +160,6 @@
 
 				renderer.render( scene, camera );
 
-				skybox.radius = params.radius;
-				skybox.height = params.height;
-
 			}
 		</script>
 	</body>