three.js/examples/jsm/geometries/RoundedBoxBufferGeometry.js

import {
	BoxBufferGeometry,
	Vector3
} from "../../../build/three.module.js";

class RoundedBoxBufferGeometry extends BoxBufferGeometry {

	constructor( width = 1, height = 1, depth = 1, segments = 1, radius = 1 ) {

		super( width, height, depth, segments, segments, segments );

		const geometry2 = this.toNonIndexed();

		this.index = null;
		this.attributes.position = geometry2.attributes.position;
		this.attributes.normal = geometry2.attributes.normal;
		this.attributes.uv = geometry2.attributes.uv;

		//

		const position = new Vector3();
		const normal = new Vector3();

		const box = new Vector3( width, height, depth ).divideScalar( 2 ).subScalar( radius );

		const positions = this.attributes.position.array;
		const normals = this.attributes.normal.array;
		const uvs = this.attributes.uv.array;

		const faceTris = positions.length / 6;

		for ( let i = 0, j = 0; i < positions.length; i += 3, j += 2 ) {

			position.fromArray( positions, i );
			normal.copy( position ).normalize();

			positions[ i + 0 ] = box.x * Math.sign( position.x ) + normal.x * radius;
			positions[ i + 1 ] = box.y * Math.sign( position.y ) + normal.y * radius;
			positions[ i + 2 ] = box.z * Math.sign( position.z ) + normal.z * radius;

			normals[ i + 0 ] = normal.x;
			normals[ i + 1 ] = normal.y;
			normals[ i + 2 ] = normal.z;

			const side = Math.floor( i / faceTris );

			switch ( side ) {

				case 0: // right
					uvs[ j + 0 ] = 0.5 - ( positions[ i + 2 ] / ( depth - radius ) );
					uvs[ j + 1 ] = 0.5 + ( positions[ i + 1 ] / ( height - radius ) );
					break;
				case 1: // left
					uvs[ j + 0 ] = 0.5 + ( positions[ i + 2 ] / ( depth - radius ) );
					uvs[ j + 1 ] = 0.5 + ( positions[ i + 1 ] / ( height - radius ) );
					break;
				case 2: // top
					uvs[ j + 0 ] = 0.5 + ( positions[ i + 0 ] / ( width - radius ) );
					uvs[ j + 1 ] = 0.5 - ( positions[ i + 2 ] / ( depth - radius ) );
					break;
				case 3: // bottom
					uvs[ j + 0 ] = 0.5 + ( positions[ i + 0 ] / ( width - radius ) );
					uvs[ j + 1 ] = 0.5 + ( positions[ i + 2 ] / ( depth - radius ) );
					break;
				case 4: // front
					uvs[ j + 0 ] = 0.5 + ( positions[ i + 0 ] / ( width - radius ) );
					uvs[ j + 1 ] = 0.5 + ( positions[ i + 1 ] / ( height - radius ) );
					break;
				case 5: // back
					uvs[ j + 0 ] = 0.5 - ( positions[ i + 0 ] / ( width - radius ) );
					uvs[ j + 1 ] = 0.5 + ( positions[ i + 1 ] / ( height - radius ) );
					break;

			}

		}

	}

}

export { RoundedBoxBufferGeometry };