Hi rodney,


> 1. is it possible to hide selected points on a spline?
> I have a lot of points on a helix that confuse me when
> editing from the top view looking down the barrel.

No, currently control points can't be individually hidden, only objects and sub-objects (edges, faces) can be hidden.


> 2. is it possible to transform/manipulate/scale splines that
> make up a surface? i.e. I create a revolve of a spline, the
> resulting object has feature curves that define the surface.
> I can select those curves but can't move or scale them.

What you are describing is a lot more how a polygon modeler works - MoI is a NURBS modeler and NURBS solids work a lot differently than a polygon modeler.

One of the big differences is that edges may not be the "natural edge" of the underlying surface but rather trim curves that are living on the surface.

See This FAQ answer for some description and illustration on what an "underlying surface" means.

So in general you don't yank NURBS solids around by their edges to manipulate them, instead you generally construct objects from profile curves rather than trying to start with some different shaped object and smush it around.

But this different approach (with "underlying surfaces", etc...) is also why NURBS solids work a lot better for boolean operations than polygon models.

You're generally better off using NURBS for models that are somewhat more "machined" in nature, where the 2D profile curves that you draw more fully define the shape of the model, although possibly in many different sub sections that you then combine with booleans.


> 3. is there any way to bend a surface after it has been constructed flat?

You can turn on control points for an individual surface and manipulate them. I do plan on adding some more kinds of deformation tools in the future, but they are not quite a natural fit with NURBS solids, see the FAQ answer above for some description.


> 4. is it possible to pick the object or point the camera revolves around? like
> a focus point. this would help a lot when zoomed in on a part of an object.

You can use the "Reset" button that is on the semi-transparent toolbar at the bottom of a viewport to center the view and the pivot point on the selected objects. Click it once to center on selected objects, click it a second time to switch to the whole model regardless of selection.

You can also use the Zoom Area button on the same toolbar to pick a specific point to focus in on, that point that you pick for the center of the zoom window will become the rotation pivot of the viewport.

- Michael

thanks so much for these explanations. I guess that explains why there aren't currently any deformation tools. I was going to suggest in the wishlist WIKI that it would be super cool to have falloff influences like Modo uses to make changes to a surface, i.e. scale that only influences the bottom of an object and gradually falls off towards the top (using various falloff curves). But I guess this isn't possible?

I'm thoroughly impressed with the amount of your involvement on this forum considering that you are also the main developer of this software. As a graphic designer i don't think I would have ever bought or dabbled in a nurbs modeling package if it weren't for MOI. Thank you for making this complex process so accessible.

Hi rodney,

> I was going to suggest in the wishlist WIKI that it would
> be super cool to have falloff influences like Modo uses to make
> changes to a surface, i.e. scale that only influences the bottom
> of an object and gradually falls off towards the top (using
> various falloff curves). But I guess this isn't possible?

Well, it is theoretically possible... But it involves a lot more complex stuff than how it works with polygons.

With polygons, you can deform all the "control points" of the mesh the faces stay connected together.

But with a NURBS solid where pieces have been booleaned, the underlying surface's control points are not necessarily aligned with the trim edges, it's more like the edges live on the surface but they only mark different areas of the surface as being active or inactive (inactive areas are holes), the edges don't actually define the shape of the surface, the surface shape completely comes from the "underlying surface" only.


It is possible to do some deformation with NURBS solids by a more complex mechanism though where surfaces are kind of resampled and reconstructed to have a bunch of control points added to them in the areas where you want them to deform, but that method kind of works better for more of "whole object" deformations like bending the whole object at once and not so much for doing sculpting-like tweaks.

If you want behavior more like you are sculpting points, it's really better to work in a polygon modeler for that kind of thing, they are much more set up with that kind of a workflow.

Most of the time in a NURBS modeler you'll be doing things that I'd describe more like "drawing curves and constructing" rather than "sculpting".


When your object is well defined by a set of 2D profile curves (a lot of mechanical type shapes fit into this category), then that's when the NURBS modeling approach works really well.

- Michael

I was remembering an image of a vintage looking microphone someone modeled in MOI and thinking it would be a lot easier to build the wire mesh windscreen on the mic if you could build it flat first and then deform the whole assembly of parts into a cylindrical form. some parts like this would be easier to break down into simple building blocks in a linear fashion and then modify later into a curved form. This might end up opening a whole world of possibilities with what people attempt to model in MOI as well. Just dreaming, and thanks for the education on Nurbs.

Hi rodney, yes I do want to work on making some deformation and bending type tools in MoI in the future. I think there is a good chance for this to happen in MoI v3.

For the time being if you want to do that kind of a thing you can make it happen by using Rhino in combination with MoI.

Copy/Paste your objects into Rhino, use the bending/warping tools (which were new for Rhino version 4.0) to alter the straight stuff into bent stuff, then Copy/Paste back into MoI.

In fact, if I remember right that microphone screen that you are referring to was actually made in this exact way by transfer to Rhino and back again.

- Michael