fix in serializer, wrong cast
fix in serializer, wrong cast

JianpingCAI/libigl,JianpingCAI/libigl,aaronzou/Shape-Deformation,JianpingCAI/libigl,JianpingCAI/libigl,JianpingCAI/libigl,aaronzou/Shape-Deformation,aaronzou/Shape-Deformation,JianpingCAI/libigl,aaronzou/Shape-Deformation,aaronzou/Shape-Deformation