Hi SurlyBird, that shortcut that Burr shows above helps out a lot to locate the areas that are have open edges.

> I got it to work one time, but subsequent attempts to repeat
> it have failed. I get a good sweep, but when I try to make a solid
> by joining the pieces, I get a joined surface as a result.

You may have fixed just one area and not all of them yet - it looks like there are about 4 or 5 areas in the model that have open edges, if you set up that shortcut that Burr posted and run it they will highlight.


Looking more closely at one of those problem edges here:



If you zoom in to that area closely you can see there is some space between the edges there:




Looking at the bottom surface, it appears to be a surface of extrusion. Probably what happened here is the extrusion is coming from this curve back here:




And that curve from back there does not exactly align with the other curve that has been used to make the front face of the model.

To make an extrusion join up with something else like that, they have to have a very precise alignment between them.

Otherwise, instead of using extrude for that bottom piece for example you could use Network or Sweep, which constructs a surface that hugs all of those boundary curves rather than only being defined by the shape of the curve on one side like an extrusion.


For these ones here, there is a simliar gap:



To fix those, delete those half-circle like surfaces, then select these 2 edges:



and run Construct > Loft to build a surface between them. That can then be joined in to solve those ones.

- Michael



EDIT: Ooops, looks like Burr beat me to it, this is mostly a repeat of what Burr wrote above.

Alway a much better explanation from Michael and I look forward to those. Also if you go to the MoI home page and look on the resources page, there is a link called "Petr's MoI Page" which has all the scripts available. Browse through those and find some gems.

Hi Surly,

Have you got any reference photographs of the gun with the area in question, reason I ask is that the model you posted isn't very 'clean' and I thought that if we had some reference the forum could help out further with some techniques to achieve what you want.

Cheers

Hi Danny,

Thanks for asking. Here are some links to images of the barrel:

http://world.guns.ru/handguns/deagle19-kit.jpg

http://www.dreadgazebo.com/gunporn/wp-content/uploads/2007/05/deserteagle.jpg

This probably the best pic I've found so far:

https://www.hyattgunstore.com/images/P/main-708.jpg

I'm not striving for super-accuracy, since the direction we're taking with this project is a bit more stylized. However, I want the gun to have a certain authenticity to it as well, so I've done a lot of scrounging for images. Probably the thing that needs the most work on my model is the scallop that terminates the groove down the side, right before the cylindrical part at the rear. My attempt really isn't accurate at all. It works well enough for my purposes, but I would like to to take a stab at it again at some point. I had to move on and finish up other parts of the gun, but I will probably revisit it again when I get the chance.

I'm interested in how others would go about creating it. My process was kind of klugey - definitely a result of my fledgling knowledge.

Hi SurlyBird, thanks for posting the pictures, those help a lot.

So one thing that can be good is to imagine how that part is actually physically manufactured.

It's not going to be built in little pieces welded together which is basically how you're approaching it in MoI - instead it is going to start with a piece of stock and then have pieces removed by drilling and cutting. Try going through more of a similar process, but you can use a lot more custom cutting heads than what an actual machine shop uses.

So like that scalloped area would probably be easiest as one long sweep that just continues to extend outside of the object instead of worrying about building pieces that are flush to one another all the time.

I'll try to make some steps to illustrate.

- Michael

Hi SurlyBird, some of the proportions here would need to be adjusted but this may give you an idea on how you could use a solids approach to building this rather than going patch-by-patch.

One part of particular interest is probably how the scalloped parts are done here - notice that I don't attempt to create those directly to their final edges but instead create them as a longer sweep that then gets intersected with other pieces. The final edges come from those intersections rather than as directly drawn curves.


I started by making a circle that I split in half and then stuck some pieces out like this:



That gets extruded:



Now select these other parts of the initial profile segments (note the bottom circle half is selected now and not the top half) :



Those also get extruded but not as far, that produces another solid which you boolean difference away from the first piece to produce this:



Now for the scallopy parts - draw in a path curve that looks something like this:



Then a closed profile curve that looks something like this:




Then use Sweep to take that profile along the path curve, to make the part that will cut the scallops out, like this:



That sweep solid gets mirrored to the other side, and then both pieces are used as cutting objects in boolean difference to make this result:



Then some other lines drawn in and boolean difference again to carve off other pieces:









So that's a pretty good illustration on how you would use a solid modeling approach keeping things more as solids at each step to build something like this, rather than going around and building it one small individual surface patch at a time.


One thing you do need to be careful of when making something bendy like the scallop cutter piece here, is that it does not bend so tightly that it starts to bunch up and intersect itself.

- Michael

Or another way that might be a bit easier to think of for building the starting piece would be something like this:

Extrude this piece short:



Extrude this circle long:



Then boolean union them together to make this:




Then continue cutting and slicing parts off as above...


- Michael

Michael,

Thanks so much for breaking the process down in such clear steps. I really appreciate your taking the time to demonstrate how things in the solids world work. I had attempted something similar to the second method you described (albeit it was still too complicated), but the scallops were still giving me grief. I like both those approaches a lot. I'm beginning to grasp it little by little and I must say, I really prefer this method of modeling over the tedious pushing and pulling of verts that I end doing in a poly modeler. I can make many, many attempts at something without feeling too invested in the process - something I never get with poly modelers. It can be a real hassle to make minute adjustments with polys, but it is *so* easy to refine a curve and regenerate a surface in MoI. Thanks for making such a great tool!

:) I knew you'd jump on this Michael once I asked for the reference photos, If you didn't, I was going to eventually.
It's the same approach that I would of taken.

Thanks!

Hi SurlyBird, yeah definitely the cool part about NURBS modeling is that you can often make things happen quickly by using some drawn 2D profile curves.

One of the key things is to think about extended shapes - if your desired result has a kind of irregular shape in some area (like with the scalloped part in this case), try thinking if the irregularity is actually more of a cut away of a larger extended simple surface.

Then if you can build those more simple extended surfaces and cut them back or intersect them with other parts, that's when you're really using the toolset to its greatest advantage over polygon vertex pushing.

But it can take a while to get used to this method if you come from a polygon modeling background since it is quite a bit different.

When the model you're trying to make is not easily defined by 2D profile curves, like if it has a lot of little lumps and bumps in it or stuff like that, that's when poly vertex pushing would tend to be the way to go.

- Michael

Hi Danny, yup it turned out to be a good example of what that means to build an extended surface!

- Michael

Damn I love these kinds of threads!

-Will