Some of your 3D models will look like a series of triangles making a mesh.…
Vectorworks Tip #158 – Document Preferences – Cropped Perspective
The option for showing a cropped perspective used to be in the View menu, but in Vectorworks 2015 this has now been moved to a Document Preference. The assumption is that you will always want to use a cropped perspective all that you will always want to use and a cropped perspective. Therefore you can set this up as your preference and you won’t have to go back and change it again.