Bad shading toggling for slope based models.

Currently switching shading off on the slope based models results in brown everywhere due to the hacky way I handled the "land" shading. 

<img width="773" height="907" alt="Image" src="https://github.com/user-attachments/assets/60ea03b9-7806-4f41-9e10-746fc45a160d" />
<img width="773" height="907" alt="Image" src="https://github.com/user-attachments/assets/3a54970f-fb32-4724-8562-602cd4944dfa" />