question

[mbp]

> 1) Once I have an object displayed, (say, an extrusion) , can I cut
>    a slice through it ? I mean, can I examine an individual
>    cross-section by specifying a cutting plane.

You can adjust the camera's clipping planes to make them very close
together, which allows you to look at a slice parallel to the view
plane.  You adjust them by typing numbers in the "Near clip" and "Far
clip" fields in the "Cameras" panel (be sure to hit RETURN after
typing new values).  The default values are 0.1 for Near and 100.0 for
Far; these are measured in units of distance from the camera position.
The camera is initially 3 units away from the origin, so values near 3
(for example Near=2.95, Far=3.05) will give a cross section through
the middle of an object centered at the origin.


> 2) If I display a surface and some points (almost) lying on it, and
>    examine it using cam orbit etc., I can see the points from both
>    sides of the surface. Is there any way of knowing on which side
>    of the surface a given point lies ?

It depends on how you are displaying the points; if you're displaying
them as VECT objects then they may be affected by the "Lines closer"
value in the Camera panel; try setting this to 0.  The Geomview
manual explains what this number does.

--Mark