# Materials: VMap Commands {#mat_vmap}
## vmap_invert
### Syntax

**vmap_invert**

### Overview

Inverts a surface normal. Works on brush faces, models and patches. Used
in celshading to achieve the inverted backfacing hull.

Can be used with a material that is targeted by
[vmap_cloneMaterial](vmap_cloneMaterial)
for something similar to
[vmap_backMaterial](vmap_backMaterial).