PDA

View Full Version : noob - Boolean substraction

MacGregg
04-29-2009, 05:20 PM
When doing a Boolean Subtraction the polygons of the area subtracted are generated by the object used for the subtraction so they don't line up with the existing geometry and mess up the seam between these meshes. Is there some "easy or easier" way to generate a better mesh seam here? It almost makes the boolean operation useless since I have to do so much editing to fix it and keeping the same surface shapes it near impossible. Ideally the Boolean operation should "fix" the polygons so they match up with to other surface.

In LW is there some way to re-generate polygons on the imaginary surface made by some polygons. I would like to be able to "slide" the polygons around to make them align better with other geometry.

JeffrySG
04-29-2009, 06:47 PM
Well I think the first thing is to take care when setting up your booleans. And then I alwY assume that there will be some cleanup after the operation. LW will just do what you set up. Depending on what the problem is though there might be different and quick ways to fix it. Until we see some examples it's hard to say.

MacGregg
04-29-2009, 08:49 PM
Well, here is an example of what I mean. Here are 2 Spheres C1 and C2 and I used C2 to carve out a chunk from C1. As you can see by the highlighted Points along the edge very few of them line up to make this mesh a nice clean mesh and it would take a lot of work if I wanted to adjust the points to align and not change the shape of the spheres in the process. Now I did not try to make it easy and align the meshes in some way first because that is not really any easier. If anything starting with spheres should have made it a bit easier, but more often then now you don't have much control over what the polygon layout on the objects would be unless you knew pretty early just what or how you were going to get to some end object.

Surrealist.
04-29-2009, 11:55 PM
Well I think Jeff already covered it.

But it would be very cool if there were tools like that. Right now there is no tool in LightWave to make that easy. Everything in LightWave is polygon based so you are stuck with lining things up. There is Dedge slide - if it still works in 9.6. That will slide the edges around, but then, at this point you are doing just as much editing anyway. And this is currently the crux of great polygon modeling. Doing anything with different shapes like that and keeping the faces smooth and even to their original shape, is exactly why it is a skill to be learned that goes beyond just the tools - in subpatch or poly mode. As it is now. Though I agree, it would be great.

Until then plan ahead, keep it simple. For now the things you are saying you are not willing to do are exactly the things you need to be doing to make it work. So line things up, plan the intersecting edges to be as close as possible, even subdivide one of them until they do if you have to. Then tweak.

Another tool that may help in certain situations is Point Normal Move. Also Shift M for Smooth. Iterations about 3 to 5.

MacGregg
04-30-2009, 06:34 AM
Oh, don't get me wrong I do do this editing... my perfectionism inclination has me spending a lot of time making point level edits. I just thought that maybe there was an easier way... I am LW self taught so sometimes I miss better ways to solve these problems. Sometimes I don't ask the right questions too, so I try to be a bit general just in case.

Like a couple months ago I asked some noob question here and discovered the wonders of MultiShift. It saved me lotsa time. ;D

Surrealist.
04-30-2009, 02:56 PM
OK, Got it. Yeah, your inclinations are correct. But that said, I still agree, there is always a faster way. AFAIK with Booleans planning is key to reducing the amount of editing.

borkus
05-01-2009, 07:27 PM
I haven't had chance to try the latest version of MoI (http://moi3d.com/) , but this is what I used to use when I knew that a model would need any amount of boolean work. It exports nicely into lightwave for the most part. Enough so that I preferred this method. Not free anymore, but it's still a steal for what it is.

MacGregg
05-01-2009, 07:45 PM
Well, the problem I have in this example is that any movement to the points on the seam here is also going to change the surface curvature unless I can keep each point on the correct surface here being a sphere. Moving these points around will make subtle changes in the local shape and can make it look crappy in short order and it can be much worse for more complex shapes.

We really need a way to move the mesh and dynamically change its resolution on the imaginary surface it creates. If I could easily spin and slide the mesh around this and many other editing tasks would be made much easier!

Surrealist.
05-02-2009, 04:24 PM
I think you are wanting something like NURBS which are in other packages not LightWave.

For the example at hand, I would not use Boolean for anything other than a simple starting place for much lower poly start point and then use Subpatches that are much more flexible.

It is really hard to do that with so many points and Booleans are not really designed for that kind of work if you have to go back and edit. If you feel it is something you are going to have to tweak, start simple.

MacGregg
05-02-2009, 09:01 PM
I haven't had chance to try the latest version of MoI (http://moi3d.com/) , but this is what I used to use when I knew that a model would need any amount of boolean work. It exports nicely into lightwave for the most part. Enough so that I preferred this method. Not free anymore, but it's still a steal for what it is.

borkus Mol looks nice, I've been playing around with the trial version. Since the trial version can't save I don't know what the object looks like when I save it for LW. If I make a boolean subtracted object as in the example here how is the NURBS to polygon translation done? Do I get any control over it. \$200 is a lot of money if all I do with this is make boolean objects. It seems like this will take some time to get used to the modeler too. The UI feels rather clumsy for me now.

I also don't know what CORE will be doing to solve this problem.

Surrealist I have done NURBS modeling with an app called Alias Sketch about 10 or 12 years ago, I liked it then but its been a long time since I've used it.

Mol might be overkill just to solve this problem. I would need to think about other 3D apps then too like Modo which looks really nice, if I am going to spend the energy learning a new app. :eek:

MacGregg
05-02-2009, 09:58 PM
Surrealist, I've been all over your website, thanks for your tutorial efforts, I have learned a lot, you really are an elegant modeler! You have great control of polygon flow!

Surrealist.
05-03-2009, 05:03 AM
Thank you. I learned from all the great modelers here over the years. Just trying to codify and pass along. Glad you got something out of it.

If you need any more help settling in with Modeler, I am glad to help. Blender is free, has limited NURBS but a few other nice features. I can help there too if you need it. :)