three
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JavaScript 3D library
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JavaScript
import { Mesh, MeshBasicMaterial, SphereGeometry, Vector3 } from 'three';
/**
* A ground-projected skybox.
*
* 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.
*
* ```js
* const height = 15, radius = 100;
*
* const skybox = new GroundedSkybox( envMap, height, radius );
* skybox.position.y = height;
* scene.add( skybox );
* ```
*
* @augments Mesh
*/
class GroundedSkybox extends Mesh {
/**
* Constructs a new ground-projected skybox.
*
* @param {Texture} map - The environment map to use.
* @param {number} height - 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.
* @param {number} radius - The radius of the skybox. Must be large enough to ensure the scene's camera stays inside.
* @param {number} [resolution=128] - The geometry resolution of the skybox.
*/
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 );
geometry.scale( 1, 1, - 1 );
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, depthWrite: false } ) );
}
}
export { GroundedSkybox };