combine/cut out 3D polygons

[Dieter @ DWorks]

How can you combine or cut out 3D polygons?

I can't see to find it.

[islandmon]

Select>3dPoly>Edit ( enter Group )>2d master

[Dieter @ DWorks]

?? I do not understand what you mean

[islandmon]

There are 2 possibilities:

1) The 3dPoly was extruded from a 2dpoly .. hence can edit via >enter>Group and using the 2d editing Tools like add & clip surface.

2) 3dPoly was created using the 3dPoly Tool and must then be edited using the

various 3dEditing Tools like combine, project, subtract surface.

If surface ( not 3d vertexial ) editing of the poly will be required I usually extrude the thing first for ease of editing and wait until the final version to convert it to 3dPoly or NURBS surface.

[Petri]

How can you combine or cut out 3D polygons?

I can't see to find it.

You don't. 3D-polygons with more than 3 vertices are not necessarily planar and therefore are "non-determined". The intersection "line" of two generic 3D-polygons is, I think, almost impossible to determine unambiguously (if at all - how do you define the path of points at the intersection of two non-determined surfaces!)

By and large, avoid 3D polygons altogether. Having said that, I use them quite a lot in my parametric objects, where I can be certain that they are planar.

EDIT

Not one my finest moments. I know what this is about. I am essentially a mathematically-oriented person. I just don't know enough to communicate the concept, because mathematics never interested me.

Edited September 28, 2007 by Petri

[Dieter @ DWorks]

So I need to do a lot of work to edit 3D polys?

I thought that it would be easy. Just like you can use 'some' 2D tools on 3D objects.