解答:改變 someObject() 的 faces.push:
geometry.faces.push( new THREE.Face3( 0, 1, 2 ) );
// the order of the face is flipped (was 2, 0, 3):
geometry.faces.push( new THREE.Face3( 2, 3, 0 ) );
另外還有兩種解法:
geometry.faces.push( new THREE.Face3( 3, 0, 2 ) );
跟
geometry.faces.push( new THREE.Face3( 0, 2, 3 ) );
面向關係到頂點的排列順序,第一個點從哪個頂點開始不重要。