code: function(cam, shader, assembly) {
      var gens = assembly.generators();
      for (var i = 0; i < gens.length; ++i) {
        var gen = gens[i];
        var affectedVAs = this._vertArraysInvolving(gen.chains());
        this._drawVertArrays(cam, shader, affectedVAs, gen.matrices());
      }
    }
docs: draws vertex arrays by using the symmetry generators contained in assembly