Theoretical SUB-D


I was playing around with SoftImage XSI 5, and they have a hard edge feature. Solves this problem real quick! Wish they had that in Max.

How about an example of how this “hard edge” thing works. Perhaps a demonstration of the same example, Square hole in sphere, would be appropiate. A smoothed and wireframe view would be nice! Pictures are worth a million words.



MAx does have a “hard edge” feature. It’s called edge tension. Or, you can use the smooth by smoothing groups option in MS. However, these methods, as well as XSI’s hard-edge feature do not do what we are talking about in this thread. Hard edges are not a good thing in all cases. Usually, one wants a soft beveled edge, which this method give you.



Dave… have you finished you Sub-D FAQ?

If so could i have a copy of it



Regarding the square thing on the sphere. I have discovered a neat little trick that solves the square edges problem when you Sub-D it. Apply a ‘Spherify’ modifier after you Sub-D! It works wonders for holes cut into spheres as well. This is in Max of course. :wink:


Here’s a little something I was playing with just to test a few things. It’s very simple but it does show what different types of loops there can be for basic sub’d. Obviously, everything is one mesh.

If your interestred I can email the file. Sorry MAX8 only.



Well, I think I finally figured out how to do a respectable looking square whole in a sphere! I haven’t been keeping up with the thread so if this is old news I apologize.

The first image is a very close-up view of the edges rendered.
The second image is a screen shot of the square hole with meshsmooth(2).
The third is a screen shot without meshsmooth applied.

It turned out to be a very simple process, once I figured out how to do it. That took a little time. There is no distortion at the corners and the smoothing looks good, at least to me.

If anyone is still interested in making a square hole in a sphere, I can do a step by step to show how it is done. This process should also work for a cylinder.



Tony Richardson wrote:

If anyone is still interested in making a square hole in a sphere, I can do a step by step to show how it is done. This process should also work for a cylinder.

I’m deffinately interested! I just tried your implementation, at least as far as I can see, and still get a flatened looking edge around the square. It certainly does not look like your final render. Perhaps what you are getting is in the order or method of your implementation… I’m all eyes…




Ok, here is my method. It only takes a minute or two once you get the steps down correctly. This was done on a 24" dia. sphere with 32 segments.

1# Cut the sphere square so that there are four triangles.
2# Select each cut and use the connect command set to one to form a square. Adjust the size of the square as needed with scale. I also used edge constraint(under edit geometry) for all this to make sure it stays flat.

3# Select the four faces within the square you created and inset by .05 inches. Do this again to from three squares within each other as shown.Now, cut from the corners of the inner most square out to the edge of the sphere square as shown in image 2.

5# Select the inner four triangle faces and then hit grow one time to select the faces surrounding them as shown in image 2.

6# Extrude the faces inward -.05 inches and close the dialog box.
Extrude again the depth you want the square minus .05 inches and close the dialog box.I did 1/2" for this.
Extrude again -.05 inches and close the dialog box.
(NOTE) Be sure to use Local Normal when extruding.

7# IF you want to, you can collapse(weld) the 2 vertices for each outer edges and move them to the center of each outer edge of the square.It’s not neccassary, but it looks cool.

Thats it! You should not have to adjust anything to get a smooth square hole.



This also works using 4 squares on a sphere for large hole.


This is a great thread - Has anyone seen these kind of methods scripted yet?

If you’re only working on a single quad to start with, I wonder if it is possible to do all the steps for creating a square or circular hole in a quad in a nicely scripted modifier.

  • Steve


Tony, great job. That’s a really good method, thanks :slight_smile:


Not sure if this was covered, since I gave up on reading this whole thread about half way through, but I can’t help but postulating:

It seems to me that the deal with Ngons reduces to this: Ngons don’t stay Ngons (at least in Max, from my experience). Max converts all geometry to tris eventually. The point with dealing with Ngons is this: do you want to explicitly control how the Ngon is divided, or do you trust Max to use its best judgement. The answer is obvious: Max is known to get this wrong, so you should always divide an Ngon into Tris and/or Quads. So factor out the whole Ngon part of the Sub-D argument.

Is there some flaw to this reasoning?

  • B


Max converts everything to tris once you render, sure but the turbosmooth and meshsmooth and hsds modifiers doesn’t just turn everything into tris… I think you got the wrong impression somewhere along the line. The thing about ngons is that they can cause weird shading and they can act up when deformed. As it is with everything else, you have to know when and where to use them. No one is saying that you can’t use them, just use them wisely.


no, but max’s own subdivider is based on a Pixar (sabre) algorithm which, adaptively divides the face. And therefore very good. Its always best to use quads i find, and tris very rarely. Tris and ngons cause rendering artifact.

The hardest part of all is having the right amount of poles to each vertex (4), man that is hard!



Hi there, I tried searching through this awesome monstrous thread but couldn’t find out if the .pdf compilation of all the great info had been completed?



Dave Black was working on it but I think he’s been too busy to finish it.


thanks for this.


Noobish question:

Why do you first convert it to a editable mesh and then poly?
IS there any benifits doing this instead of mkaing it into a editable poly directly?


What was the context in which I said that? Probably when dealing with cylinders. There was a bug in max 5 that duplicated the bottom faces of the cylinder when converted directly to EP. In later versions, this is not necessary.

How that helps.



thanks for your post and I had to test it with only quads.

from the bottom of the hole I deleted edges so I got 9 quads remaining. Got rid of the x-shape. have you tried that ?