This question came up today and it is a tough one - however with some testing you can solve it using the Curtting Plane View. The things you need to know about Cutting Plane View are
- Any object that you draw in the cutting plane will have a UCS (User Coordinate System)
- Define the plane using the TBC Plane Manager
- You can remove the UCS on an object drawn in Cutting Plane View using the Convert to Linestring command - this makes it a normal 3D object in TBC allowing you to draw to it / from it
- Objects drawn in Cutting Plane View while they have a UCS cannot be drawn to, joined to etc by objects in the normal Plan and 3D views that do not have a UCS - but remove the UCS and you can use them like any other object.
- If you draw a Polyline in the Cutting Plane View it is drawn on the cutting plane automatically.
- If you draw a linestring in the cutting plane view, because a linestring can have variable Z then it does not necessarily get drawn in the cutting plane unless it has UCS 0 elevation.
- If you use the Change Elevation Command on objects in the Cutting Plane View, it moves them perpendicular to the cutting plane (this is very handy)
Anyhow - now you know some of the secrets here - the video shows how to construct the perpendicular from a point in space to the plane and also from a point in the plane to an offset location to the plane but perpendicular to the plane.
Computations perpendicular to an inclined plane