Hello there! I'm trying the demo in the hope that MoI can handle some kinds of objects that are difficult to produce in modo or Sketchup--in particular, things like plumbing fixtures (faucets, sinks, tubs, toilets etc). I've been trying to to produce a tub/shower spout (see image), and have made some progress and had some fun. I love the MoI user interface! The problem is that the spout has a giant surface (in the real world) that runs from the opening where the water comes out, along the side and then wraps up around the circumference at the back. How to create this surface or others like it? Any help would be greatly appreciated!

Hi pelanglo,

> The problem is that the spout has a giant surface (in the
> real world) that runs from the opening where the water
> comes out, along the side and then wraps up around the
> circumference at the back.

Can you post an image of this big surface so we can get a better idea of what it looks like?

But yeah for a large flowing surface you're most likely going to be drawing in some guide curves and using either Sweep or Network to construct the surface from those guides.

One thing I notice from your screenshot above is that it looks like you're building your spout by building just individual surfaces edge-to-edge that fill in a wireframe outline.

That can work, but a lot of times it can be easier to initially build a larger more complete solid to start with and then carve off scalloped out bits using a boolean command, rather than trying to directly build each little surface directly and individually. Incorporating some cutting operations rather than only all edge-to-edge surfacing can tend to make things a lot easier.

So for instance to make a cut out part you might start with a solid like this:



Then go to a side view and draw in a 2D curve something like this:



Then select the solid, in the 3D view it looks like this:



Then run the Construct > Boolean > Difference command, and select the 2D curve as the cutting object. That will slice the solid up into 2 pieces by the projection of the 2D curve - select this piece here:



And then just delete that piece you don't want to get this result:



So note that the key thing here is that a portion of the final model came from a cutting operation that was done by a 2D curve (where the projection of that 2D curve becomes part of the model), instead of trying to build a full 3D outline of those edges and trying to build a surface directly between those 3D outlines.

If you have any area of a model that seems like it is a carved away portion, it's generally much better to model it in that actual way, starting with a larger extended piece and then carving it.

This is the area where a NURBS modeler is very different than a polygon based modeler - you want to use booleans and cutting operations as a primary way of working with NURBS when possible, while in a polygon modeler you are probably used to avoiding them and only using them as a last resort.

- Michael

Thanks for the reply Michael. MoI definitely requires a new way of thinking, which is very challenging! I didn't know about slicing with a curve like that--very useful!

Here's the spout from the side, where you can get an idea of what I'm talking about:



At the opening, the side surface I'm trying to model is essentially vertical, and very slightly convex (if you looked at it from above). Conversely, where the spout is attached to the wall, the surface has become cylindrical. To me, there doesn't appear to be an obvious base shape to use that could then be carved away with booleans or trimming, which is why I was assembling part by part (after having no luck with sweeps, lofts or networks...). It seemed like such an easy project when I began!

See if you like this one... I made it with your curves.

One limitation of MoI is that it doesn't have surface continuity options when creating patches or network surfaces.
If I was making this in Solidworks, I would do what Burr has done but cut away the surface at the top and re-patch it with a curvature continuous surface.

Perfect--just what I was hoping to see. How did you accomplish it?

I swept the back profile to the outlet profile (I had to modify the outlet profile to get a good sweep) with the 2 bottom rails... Then I took the curve from that original little top cutout you had made, and used to to boolean away the top (as Michael had just showed you... You can extract the edge of that cutout piece and flatten it in the top view with the edit frame, then extend the ends to be beyong the new swept surface) Then I deleted the flat surface from the boolean difference and created 2 segments of that inner edge to run a blend command on.. So that top piece is G2 curvature.. I could do this with the bottom piece too, but left it as it was because you had drawn it that way and figured you might want it to be shaped like that..

If this is too hard to follow, I could do some screen grabs for you..

Hi Steve.. The spout I posted is G2.. In my last post, I stated that it was only the top, but pretty sure it is the top and bottom piece also... FYI.

Hi pelanglo, ok I see what you mean now - sorry I had misinterpreted what you wrote earlier and I somehow thought you were talking about some kind of custom elaborate water catcher thing coming down from the spout.

So yeah something like that where there is more of a gradual continuous change from one shape to another probably won't really work with just one simple boolean, you will need to do either sweeps or networks to form the surfaces in that case.

But working on a shape that has no strong 2D profile element to it means that your project isn't really leveraging the greatest strengths of NURBS modeling as compared to polygon/sub-d modeling.

As a model becomes more sort of amorphous or all melty looking in shape, those are actually the kinds of shapes that polygon/sub-d modeling can work really well for.

You can still do such things with NURBS, but you will be working with a more advanced and harder to learn toolset area of doing a bunch of freeform surfacing with 3D curve networks.

Models where you're able to leverage 2D curves and booleans for producing your model is really where NURBS modeling greatly excels when compared to polygon/sub-d modeling.

Shapes like you want to do here are kind of a bit in a gray area, not really driven by 2D profiles very much but also not so fully organic like a human face or something like that either.

- Michael

So if you want to see it, you can open the file I posted and delete these 2 surfaces here:



After you delete them, look from the right side view and notice it is just a cutout of a sweep, like michael posted..

Then run the blend command on the 2 opposing edges from the top, then the bottom pieces.. Adjust, rinse and lather...

Thank you both for the *extremely* useful replies--it's particularly helpful getting both the theoretical/conceptual info as well as the workflow approach on how to use MoI on these kinds of objects. Actually, just knowing that there are relatively straightforward solutions for shapes like the spout is encouraging, and the final result is much cleaner than I could get out of modo, so I'll keep playing around with the demo. Seems like there is definitely a spot in the toolbox for MoI.

So what Steve was pointing out was using the network tool, has no mechanism for maintaining the tangency to surrounding surfaces...

So here if I broke this edge here to enable a blend at a much higher value in this upper area:



To look like this... I might try to fill in this last area with a network:



So I could select these curves and run network on them:



And I would get a nice surface patch in there:



But at the moment, MoI doesnt have a means for the network patch command to "Know about the surfaces next to it"... So you can get a lack of tangency from the surface previously made. You can see the hard edge here now..



So, building by "Patchwork" would be fairly hard or advanced as michael mentioned....

I think Michael said he was working on some surface continuity options.

I'm not working on them right this moment, but I have some good ideas on how to pursue some continuity functions for v3 though.

- Michael

That would be awsome Michael.

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