error C2338: YOU_MIXED_MATRICES_OF_DIFFERENT_SIZES

使用Eigen时报以下错误：

error C2338: YOU_MIXED_MATRICES_OF_DIFFERENT_SIZES

参考https://blog.youkuaiyun.com/Charles_ke/article/details/89067150得知应该是Eigen矩阵维度不相同导致的问题

通过注释相关代码定位到报错的位置：

for (int i = 0; i < loop_size; i++) {
            Vector3d pos = current_V.row(mainLoop[i]);
            new_vertices.row(i) = pos + expansionDirections.row(i);
        }

由于expansionDirections.row(i)既可以代表行向量又可以代表列向量，使其与列向量pos相加会出现维度不兼容的情况

解决办法如下，将expansionDirections.row(i)赋值为与pos一样的列向量，再与pos进行运算，不再报错

for (int i = 0; i < loop_size; i++) {
            Vector3d pos = current_V.row(mainLoop[i]);
            Vector3d dir = expansionDirections.row(i);
            new_vertices.row(i) = pos + dir;
        }