I find a bug also :) https://www.freecadweb.org/tracker/view.php?id=3418 I build a simple box ant export to html , it can not open by browser. geom.faces.push( new THREE.Face3(0L, 1L, 2L) ); geom.faces.push( new THREE.Face3(3L, 1L, 0L) ); geom.faces.push( new THREE.Face3(4L, 5L, 6L) ); geom.faces.pu...