VertexColorBoxGeometry.js

class VertexColorBoxGeometry extends THREE.BoxGeometry {
    constructor(width: number, height: number, depth: number, widthSegments?: number, heightSegments?: number, depthSegments?: number) {
        super(width, height, depth, widthSegments, heightSegments, depthSegments);

        let faceIndices = ['a', 'b', 'c', 'd'];
        for (let face of this.faces) {
            let numberOfSides = (face instanceof THREE.Face3) ? 3 : 4;
            for (let i = 0; i < numberOfSides; i++) {
                let vertexIndex = face[faceIndices[i]];
                let point = this.vertices[vertexIndex];

                let color = new THREE.Color(0xffffff);
                color.setRGB(0.5 + point.x / width, 0.5 + point.y / height, 0.5 + point.z / depth);
                face.vertexColors[i] = color;
            }
        }
    }
}