Hi Paul - in general you can't grab individual faces and edges, because often times those edges are not actually edges of the "underlying surface" and are instead "trim edges" which are marking areas of a surface as being holes or cut away parts.

A box that you create with Draw solid > Box is a special case though - you can turn on control points for a box with Edit > Show pts and then select 2 points for one edge, or 4 points that make up one face and then scale or move those points around.

But like I said, that's a special case - after you have done some boolean operations your objects will be made up of surfaces that have trim curves on them instead of all untrimmed surfaces like the box happens to be.

So in general in MoI you don't pull edges or faces around like you would do in a polygon modeling type program - instead the regular way to make something like a pyramid shape would be more to draw it directly by drawing 2 rectangles one above the other, scale the upper rectangle down, and then construct the pyramid by doing a loft between the 2 rectangles.

That's more of the general workflow - draw profile curves, which you can shape however you need (by control point manipulation, scaling, offsetting, whatever), and then construct the final shape that you want from those curves, rather than starting with some other shape like a box and modifying it - that's more how a polygon modeling program works which has a much different workflow.

There is some more information on how an "underlying surface" works in the FAQ answer here:
http://moi3d.com/wiki/FAQ#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F
That tries to explain how objects with trim curves are structured, and why it doesn't really work to try and edit one surface when you've got 2 of them that are meeting up at trim edges.

Also see here for some other various posts with additional explanations on this subject:

http://moi3d.com/forum/index.php?webtag=MOI&msg=4605.7
http://moi3d.com/forum/index.php?webtag=MOI&msg=3628.200
http://moi3d.com/forum/index.php?webtag=MOI&msg=4052.6
http://moi3d.com/forum/index.php?webtag=MOI&msg=4050.3
http://moi3d.com/forum/index.php?webtag=MOI&msg=4360.9
http://moi3d.com/forum/index.php?webtag=MOI&msg=3539.1

 

Basically the way MoI's modeling paradigm works is more like "construct objects from drawn curves" and not so much like "tweak edges and faces of a 3D solid" like a polygon modeling program.

But it's also because of this different style approach that MoI has a totally different set of strengths and weaknesses as compared to a polygon modeling program which is really what makes it a nice companion, because the "construct from curves" approach tends to work really nicely with a wide variety of mechanical or man-made type objects that are defined well by 2D profile curves.


Hope this helps to explain things a bit more!

- Michael

Hi Michael,

Thank you for your rapid response!

Yes, I think i'm thinking of a 'poly modelling' workflow, which is my mistake...even so, I can still do what I need to do, just thought there may have been a 'lazy' way to do this...:)

Great program btw...purchase imminent...:)

Best regards,

Paul

Hi Paul, yeah it's pretty different than polygon modeling, in some other ways too - another thing that tends to throw people with a polygon modeling background off is that in NURBS modeling using trimming and boolean operations is the main way to do things.

A lot of people coming from a polygon modeling background have become accustomed to only using booleans as a kind of last resort since it causes a lot of problems with polygon modeling.

It can take a bit of adjustment to instead look to cutting and booleans as a primary tool.

Often times a particular area that is hard to get thinking of is that some shapes are more easily built by making a larger more simple extended piece initially, and then cutting away parts of it to get the final edge structure. I often see people from a polygon modeling background trying to draw in all the final edges from the start and then try to patch surfaces in between them, but a lot of the time cutting pieces off is way easier than that and more of a natural fit with the NURBS toolset.

Here are some other discussion threads that show some examples of this kind of stuff:

http://moi3d.com/forum/index.php?webtag=MOI&msg=3795.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=4298.4
http://moi3d.com/forum/index.php?webtag=MOI&msg=4163.1
http://moi3d.com/forum/index.php?webtag=MOI&msg=2282.2


There are quite a lot of mechanical shapes that are handled really well by this technique, and the nice thing about doing cutting operations is that you can make cuts with 2D profile curves that are really quick to draw. So for the right kind of mechanical-ish type objects the NURBS modeling approach tends to make those kinds of models come together really fast from just 2D input, that's basically where the toolset shines.


For things that are more fully organic and aren't really well defined by 2D profile curves (think stuff like faces, creatures, etc...) then those types of models are not as good of a fit with the NURBS toolset and those kinds of things tend to work better with a polygon modeling program instead of MoI.

But that's also why MoI makes for a nice companion to use along with a poly modeler - it gives you a really different kind of toolset to use in the right situations.

- Michael

Hi Michael,

Thanks again for your input!

After spending only six hours with Moi3d, i'm already impressed with the results i'm getting....

I shall have more of a read later on today.

Bed calls...:)

Best regards,

Paul