解答：SquareGeometry() 的程式：

// 產生頂點
geo.vertices.push( new THREE.Vector3( 0.0, 0.0, 0.0 ) );
geo.vertices.push( new THREE.Vector3( 1.0, 0.0, 0.0 ) );
geo.vertices.push( new THREE.Vector3( 1.0, 1.0, 0.0 ) );
geo.vertices.push( new THREE.Vector3( 0.0, 1.0, 0.0 ) );

var uvs = [];
uvs.push( new THREE.Vector2( 0.0, 0.0 ) );
uvs.push( new THREE.Vector2( 1.0, 0.0 ) );
uvs.push( new THREE.Vector2( 1.0, 1.0 ) );
uvs.push( new THREE.Vector2( 0.0, 1.0 ) );

// 產生面
geo.faces.push( new THREE.Face3( 0, 1, 2 ) );
geo.faceVertexUvs[ 0 ].push( [ uvs[0], uvs[1], uvs[2] ] );
geo.faces.push( new THREE.Face3( 0, 2, 3 ) );
geo.faceVertexUvs[ 0 ].push( [ uvs[0], uvs[2], uvs[3] ] );