Hi NightCabbage,

> I think I understand it, but I'm still not sure why you
> couldn't change the trimming curves, except for the one
> problem of if you tried to move then outside the surface.

Well, you can't re-shape the surface by changing the trimming curves, which would probably be normally what you would expect to do by editing them like you would in a polygon modeling program.

For example, when you edit edges in a polygon program, it is not unusual to move the edge up or down in 3D or stuff like that to mush the points all around.

It would be theoretically possible to edit the trimming curves but it would not behave like the polygon modeling editing, it would be more like you would drag the curves around within the surface but not be able to move them up or down off the surface or stuff like that.

In the future at some point it would be good to try and enable that kind of special trim curve editing, but it will take quite a bit of work since there are all kinds of situations to look out for, like you can't make trim curves cross over one another or have outer loops cross over inner loops, deal with other edges and loops that are joined with that one, etc... etc...

- Michael

I think I'm beginning to understand the complexities of a NURBS system...

I'm glad to see that you're interested in adding these features in, however, as I really think you have a great product :)

Hi NightCabbage, yup I'm definitely interested in them, but they aren't really a "natural fit" with the NURBS structure and will require quite a lot of work to make them happen in a way that does not make broken or invalid objects too easily.

So that means I don't really know when it will happen, possibly not for a fair amount of time.

- Michael

I usually use the command 'ShrinkTrimmedSurface' which shrinks the underlying surface to the boundaries of the new shape.
You can find the explanation here....... http://moi3d.com/wiki/Hidden_Secrets
12th Secret from the top.

Cheers

I also struggled a bit with NURBS at the start. I had only just started to get the hang of polygons :-)

I try to think of NURBS more as a block that I am going to cut bits away from to make my final shape. I use other shapes to cut the block into whatever you want. I use booleans and extrudes more than planes.

For your building I would have started with a block then used another block to cut out the corner. This would have left me with a solid model.