As far as I can tell, this command is designed to "bend" a bounded plane creating a second slope.
But as we've seen with other commands, this happens in a series of operations and "layers" and I've found it helpful to try to pick these things apart to better understand what's going on. When you launch the command you are asked for:
- A grid to modify (we'll call this Plane A)
- A key point on the grid you selected to be modified
- A slope direction
- A slope value
- The boundary of a new plane
Here's what happens:
- A new bounded flat plane is created (we'll call this Plane B) which passes through the key point at the slope and direction you've specified.
- Plane B is dynamically tied to Plane A at the key point. If you raise or lower Plane A, Plane B will move with it. You cannot raise or lower plane B manually.
- A new grid is created by adding Plane B to Plane A using the Bottom Envelope command.
- Also, a new plane is created which is sloped to match Plane B but is bounded within the feature line you selected as prompt #5 above. As of right now, I don't know what this plane is for or why it is created, but maybe I'll figure that out or have it explained to me another day. Interestingly, this plane is the "live" plane that you edit if you want to change the slope of Plane B. If you use the same feature line that bounded to the original plane, then naturally this plane looks exactly like Plane B.