Migrating to modo from lw. Got trouble :p

bac9i4mo · Aug 2011

Hi there!
I'm a newcomer to modo and will probably have several mind conflicts till i fully adapt.

First, i see modo is not very good at triangulating complex >4pt polygons. ;p

Same as lw, actually. But this is never a pain if you got the tool to fix it.
My eye detects these non-fair lengthy edges automatically, so i can simply select them, merge and triple again. Or do a direct quad spinning to pairs. In this mesh, for example, i'd spin 5 groups of polys for a more optimized/beautiful mesh.

But this is manual labor, which eats time. LW has a nice dxs_relax plugin (wrote by Dratov Denis), which effectively does this edge spinning job without modifying point coordinates. Proof here:

Any similar method in modo?

Another question is about planar/cubic mapping. Procedural planar or cubic mapping a is very useful technique for building levels.
But to push these meshes any further (export to .fbx in my case) i need this mapping data converted (baked) to UVs? I did this in LW using Texture Guide tool with Make UVs option enabled. Is this possible in modo? Been digging for a day, found nothing yet.

Please refer to these q's as 1. (optimised triangulation) and 2. cubic mapping.
Thanks in advance! ;p

bac9i4mo · Aug 2011

Tell me, modo/lw guys. Does anyone actually use cubic mapping in level design?

Farfarer · Aug 2011

You can spin just an edge - doesn't have to be a pair of polys. Just select the edge you want to spin and run the same command. It shouldn't mess with the UVs unless it's a border.

I've got it bound to v... but I can't remember if that's standard any more.

bac9i4mo · Aug 2011

Heh, thats manual labor. Check that circle on a second picture, wonder how much time will it take to spin them edges

EarthQuake · Aug 2011

Yeah, but why would you end up with such a nasty mess of topology in the first place? I've used LW in the past and have used Modo for the last 5 or so years, and I wouldn't ever really have this problem in either.

Swizzle · Aug 2011

I'm honestly not sure what kind of mesh would lead to that sort of UV map, so this seems like a slightly odd request.

That said, Modo isn't very good at guessing the best triangulation for complex n-gons. High-detail extrusions like text are often pretty bad if you just let Modo handle everything, but in that case you should just add some point-to-point cuts in a few key places and it'll sort out triangulation fairly well. I do that all the time and it only requires minimal readjustment later on. Think of it a little like adding support edges to a high-poly mesh.

bac9i4mo · Aug 2011

A simple example of modo's triangulation algorithm:

Well, i'm not happy about the left example, but i get really pissed off about that crap on the right. Thats a clear degenerate (almost zero area) plus Tjunction/hole. Why would modo want to do it this way?! It completely ignores unbalanced weights of resulting polygons area.

I know many artists simply dont know how their things get triangulated and leave it like that. Some of these problems will be fixed only if they get noticed in a game by QA team. Several game engines have their built-in tools to detect such bad polygons.

But no matter how good is your engine or QA guy, such cases should never leave your modelling tool. Or even never come up in your modelling tool.

So, i guess we are forced to manually select these polygons/edge and spin, spin, spin. Which wastes a lot of our time.
Or there is some alternate triangulation tool around?

EarthQuake · Aug 2011

Generally, in cases where triangulation will tend to be unpredictable, I will simply cut in the mesh flow I want. I try to avoid doing a lot of work with messy ngons that are a mix of concave and convex edges like you have on the right. So yeah, just the cut tool. I would do this in any app though, not just modo.

Its always a good idea to manually set your edgeflow in areas that you know will be prone to poor triangulation.

The left example, while it could be slightly better by spinning that one edge, the bigger problem is you simply would not want to use that sort of topology for a game asset. You want to avoid long, thin triangles because of issues with texture resolution(resolution based smoothing errors with normal maps) and the fact that drawing these long, thin triangles is generally a rendering bottleneck.

In practice, these issues should be very minor, and you shouldn't have a problem if you're working cleanly.

EarthQuake · Aug 2011

I was just curious so i did a couple tests, I actually had to try very hard to get triangulation like your right example, it seemed to almost always triangulate how you expect, until i finally pushed and tweaked a vert around to get apparently the worst case sort of triangulation, like you have there.

However, thats with a nasty T shaped ngon, that you generally shouldn't end up with anyway.

Another test:

A. Potential to be bad
B. However, triangulates exactly how you would expect.
C. Is how this should look in the final, clean lowpoly model anyway, no chance of bad triangulation.

Now, in addition to all of that, relying on a tool or scripts to properly clean up your topogy at the end of the day, I really wouldn't recommend it. Its much better to simply be in control of the situation.

Especially when you start talking about baking normal maps and such, if you need to make revisions, its an awful pain to make a copy of your mesh, run it through your tool/script, do you bakes, and then find out you need to make changes, revert back to the original, make your changes, rinse, repeat. Because this certainly isn't something you can do after baking a normal map for instance. Just make a clean mesh in the first place, that will save you more time than anything.

bac9i4mo · Aug 2011

EQ, you got a perfect T-shape. But when you cut through bricks or do some damage to asphalt using pen tool on a textured poly, you never get that kind of perfect mesh shapes.
So, in my case avoiding this problem is not possible. Well, i believe thats not strictly my own unique case - its a pretty common problem in game level creation.

bac9i4mo · Aug 2011

Ok, so I've found a person who understands me and my problems and.. He made a script that fixes all triangulation errors made by modo.
Example image here:
http://mymodo.ru/sites/default/files/object/smarttriangulation.png
Download page here:
http://mymodo.ru/preset/smart-triangulation
That's a russian modo community site, everything is written in russian, but the link to that script is clearly visible.
It works both with poly/edge selection and with no selection at all. It swallows any type of polygons (3-,4-,n-) and outputs a nice triangulated mesh.
Run as an external script (@smarttriangulation.pl x) where 'x' is an optional int which sets the number of iterations. 5 iterations are set by default, which is enough in most cases.
Updates planned also, so check back (balancing polygon areas, for example).
Credits to Dmitry Bersenev aka Mynglam.

Happy spinning, everyone else

Migrating to modo from lw. Got trouble :p

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