If some of your triangles are clockwise and others are anti-clockwise, backface culling will be messed up, and holes will randomly appear in the mesh when viewer in real-time.

• 如果有些用顺时针，有些逆时针，隐面剔除就会发生错误，实时检测模型时就会看见网格上有随机出现的漏洞。