code: function separateFaces(geometry) {
      var vertices = [];
  
      for (var i = 0, il = geometry.faces.length; i < il; i++) {
        var n = vertices.length;
        var face = geometry.faces[i];
  
        var a = face.a;
        var b = face.b;
        var c = face.c;
  
        var va = geometry.vertices[a];
        var vb = geometry.vertices[b];
        var vc = geometry.vertices[c];
  
        vertices.push(va.clone());
        vertices.push(vb.clone());
        vertices.push(vc.clone());
  
        face.a = n;
        face.b = n + 1;
        face.c = n + 2;
      }
  
      geometry.vertices = vertices;
    }
docs: Duplicates vertices so each face becomes separate.
  Same as THREE.ExplodeModifier.
  
  @param {THREE.Geometry} geometry Geometry instance to modify.