9
$\begingroup$

For curved meshes I've often noticed that in my desperation to avoid tris, I tend to extrude the mesh in a way which creates these long rectangular quads:

enter image description here

In this case at least, the mesh is all quads, however the edge flow causes loopcutting to be awkward in some places:

enter image description here

I tried creating the same mesh with more even topology, however I found tris unavoidable. Maybe it was because I was starting with the long-quad mesh, but I also found myself using the knife tool for everything..

enter image description here

This makes loopcuts less necessary and easier to place in most cases, though the occasional tri does get in the way.

An annoying thing about the tris are the poles, though they aren't too noticeable in this particular case.

enter image description here

Both techniques seems to have their advantages and their disadvantages:

enter image description here

Which is considered "better", if any? Are there any better workflows for creating even topology with as few tris as possible? Or is there some trick I'm missing altogether?

Blendfile

$\endgroup$
  • $\begingroup$ Perhaps you could upload the blend for this piece so we can experiment with topology? Personally I'd go for a sort of mixture of both methods, but it's hard to explain without showing you. $\endgroup$ – Greg Zaal Jun 10 '14 at 7:01
  • $\begingroup$ @GregZaal Whoops, I actually did mean to put the file up, but somehow forgot.. Added :) $\endgroup$ – gandalf3 Jun 10 '14 at 18:22
10
$\begingroup$

Topology is a weird thing. It can be done a few different ways, and there isn't always a right answer. However, a few rules to keep in mind while modeling:

  1. Edge loops should be around defining features and edges. For example, if you have a hole in your mesh, there should be a loop around it. It makes the shape easier to change and makes creasing the mesh with more edge loops much simpler.

  2. Try to keep a quad based mesh. If you are forced to use a triangle or n-gon, try to hide it away on a flat surface, or a hidden part of the mesh, where, when it messes with the subsurface modifier, the distortion will not be as noticeable.

  3. Try to keep quads even sized and square. Otherwise you'll have weird stretching issues.

So, to answer your question, you want an edge loop around the bottom with squarish quads inside:

topology diagram

It will be easy to change the shape of your mesh and it will work nicely with the subsurface modifier.

$\endgroup$
  • $\begingroup$ This looks pretty much like the "long quads" example, except with some loop cuts down the middle. I guess the only problem with that is I end up with a rather lot of cuts close together at the back, where the model is narrower than the front. Should I just fudge it and try to space them out as much as possible? or is there another trick? $\endgroup$ – gandalf3 Jun 10 '14 at 18:21
  • 1
    $\begingroup$ @gandalf3, the main point is the edgeloop around the side. It separates the flat part out (so it won't affect the shape). $\endgroup$ – CharlesL Jun 10 '14 at 18:49
2
$\begingroup$

I think you already know this but anyways, for loop-cuts, there is a hidden option that works well with curved and irregular geometry.

Once you've set the loop and it's in slide-mode(yellow), then you can now press the e to enter edge-parallel* mode. This mode has 2 options that can be toggled using the f key.
f will determine which parallel edge the loop becomes aligned with.

Now there is also the SIRE outline tool which I rarely use but when its needed it's the best solution that I know of so I always have it installed. I think it would work well as a starting place for the type of model you posted in your question.

enter image description here

Here's a link to the BlenderArtists thread for this addon package.http://blenderartists.org/forum/showthread.php?179375-Addon-Edge-fillet-and-other-bmesh-tools-Update-Jan-11 You can install just the individual tools that you want instead of the whole package. :)

ps. What CharlesL did looks really good. If adding a displace modifier to that model, the high-frequency detail will show up more evenly than it would for quads that have irregular sides and spacing. The same would be true for multi-res sculpting. enter image description here

$\endgroup$
  • $\begingroup$ Actually I didn't know about those shortcuts for edge slide, thanks! $\endgroup$ – gandalf3 Jun 10 '14 at 20:26
  • $\begingroup$ I forgot to mention the (e and f)options also work for both of the edge-slide tools. double-g or shift-v. $\endgroup$ – MarcClintDion Jun 10 '14 at 20:52
  • $\begingroup$ And also loops cuts (ctrl+r) $\endgroup$ – MarcClintDion Mar 15 '15 at 7:09
  • $\begingroup$ please do not add text in the images (bad for searching and screen readers), and even more so please do not use squiggly free hand text in images (bad for reading). $\endgroup$ – David Jun 2 '15 at 0:17
1
$\begingroup$

Which method is better will depend, at least in part, on how the mesh is to be used. Since some game engines, especially older ones, convert meshes to tris for rendering, meshes used for creation of game assets on these platforms engines, tris are of rather less concern. On the other hand, preparing meshes for 3D printing seems to be a "tri-phobic" (to invent a term) endeavor.

But each additional vertex in a mesh adds to rendering time, as a general principle, in the absence of any other considerations, the mesh with the largest possible faces, and thus the fewest number of vertices consistent with the desired result, would be better than one with more vertices.

$\endgroup$
  • 1
    $\begingroup$ All game engines and render engines convert quads (and ngons) to tris for rendering. $\endgroup$ – Greg Zaal Jun 10 '14 at 12:29
  • $\begingroup$ Why would tris be a particular concern in 3D printing? I've never printed anything before. $\endgroup$ – gandalf3 Jun 10 '14 at 18:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.