View Full Version : Creating Planar Polys

07-08-2004, 06:55 PM

I did a search and read some stuff here on non-planar polys and how to prevent them, but I wondered if there was a way to do so other than selecting points and setting a specific value, subpatching or tripling. I don't subpatch all the models I make (not that there've been a terrible lot so far), and I've read over and over that nothing but quads will do. Quads are king.

And going thru a model and setting points for each poly -- well, that's a bit mind boggling.

Also, are non-planar polys really that terrible? I noticed some of the objects that ship with LW have lots of non-planar polys, and they look fine to my newbie eye.


07-08-2004, 10:16 PM
I beleive that non planar polys are not really described very well. What non planar polys do is place points on different planes in the 3d universe. Some people just use triple for a quick fix. I suppose there maybe times that is the only fix, but I am not going to debate that. Let's take a four point poly for example. If your were to use the knife tool on that poly and kill the poly and then create poly, there is a chance you will end up with a non planer poly.
Odds are if you check the four corners of that poly, you will find at least one corner that has two or more points. Lightwave is trying to create a poly using multiple points in one corner or more of your poly. Therefore the poly is existing on more than one plane. Even if the two points share the same location in 3d space, LW still sees this as an error and visually shows you by displaying a black poly.
Another way to get non planer polys is to unweld your points, kill the polys, create poly by selecting multiple points for your poly.
I am sure there are other ways that I have not discovered yet, that someone else will point out, or even correct my discription. But, I think this should at least give you an idea of what causes this modeling error.

07-09-2004, 02:55 AM
While modeling with mainly quads is nice, it's not the only way to do things, trigons and ngons all have their place. And that's just it, it's all about placement and use. Arbitrarily tripling your polys is 99% of the time the wrong way to go.

The easiest way to prevent non-planar polys is to model with subpatch turned off. If your polys are all facing the correct way (assuming the polys are one sided), then a poly face will disappear if while moving points it becomes non planr. Just by moving a point back into a plane with all the other points it shares with a polygon, the face will return and become planar again. You can check to see if yor polys are aligned by using the align command under the detail tab in modeler. Flip any polys that aren't.

Don't make it too complicated by setting any point values. All a non planar poly is, is a polygon with a corner that's not on the same plane as the other corners. Simply moving the point is the easiest way.

Another thing to remember is that polys can become non planar while being animated because again, a point can move out of a plane with the other points shared on the same poly.

07-09-2004, 04:57 AM
Thanks a lot for the info. Very helpful! :)


07-09-2004, 09:37 AM

Another point to mention would be the "flatness limit", found in Modeler - general options. If that value is zero, then even the slightest out-of-planeliness will cause a non-planar-failure. By default that value is at 0.5%, and so there is a little tolerance with non-planars.
Basically, when you use the standard LW create- and multiply-tools (bevel, extrude, mirror etc) you will never get a non-planar poly, only with modifying single points with drag, bend, twist etc you can create them, and that is the point where "triple" comes into play.

07-09-2004, 11:30 AM
When creating organic models I find it near impossible to create a mesh that isn't mostly non-planar in the poly state but when I turn on subpatches the non-planars seem to disappear. I have been working on a hand that has 826 quads. In subpatch mode no non-planars are listed, but in poly mode there are currently 802 non-planars. I assume that the process of subpatching is triangulating the model. It renders just fine.

07-09-2004, 11:31 AM
And the drag tool is one of my favorites...as are the move and rove tools. :)

You're right about the standardized tools -- when I make a shape using ball, square, etc. -- no non-planars. Guess I'll just stick to subpatch mode to straighten the others out. :) Maybe if I just wanted more polys w/o SubD, I could use subpatch at a low setting and then freeze?

But I can't think why I wouldn't want subpatches unless I was modeling an object with a standard shape anyway. :)

Thanks for the info Shliome -- and again, hr and silkchicken. ;)

07-09-2004, 11:33 AM
Hey, bloontz:

We were posting at the same time. That's my situation exactly! In non-SubD mode, I have non-planars galore. But subpatching fixes 'em, thank goodness. :)


07-09-2004, 11:37 AM
Subpatches can take longer to render, sometimes freezing can speed things up. I admit to being a subpatchaholic though.

07-09-2004, 08:53 PM
It's impossible to have non-planar subpatch polygons because each one is made of multiple 'real' polygons after being calculated/subdivided.

07-10-2004, 05:07 AM
That's good news. Hit a button, and the non-planars are fixed. I wonder if you set the subpatch level to 0 and hit freeze, it'd still fix the non-planars while retaining the poly count.

Gonna try it out.

07-10-2004, 05:12 AM
Sheepish grin...:eek:

You can't set the patch level to zero evidently -- duh on me. And the poly count stays the same no matter what the level of subpatching. I thought it changed.

You can tell I'm a newbie. :eek:

07-10-2004, 05:26 AM
Nope, doesn't work. So much for my blast of inspiration. :rolleyes:

In subpatch mode, no non-planar polys. After freezing, at levels 1 & 2, the non-planars return.

Sure smooths out the appearance of the model though. :)

07-11-2004, 12:48 AM
"but I wondered if there was a way to do so other than selecting points and setting a specific value,

And going thru a model and setting points for each poly -- well, that's a bit mind boggling."

I'm not sure if this is what you're looking for but here's a dirty trick. In order for you to determine the newly created points to lie on the same plane without regards to their numeric value.. you will need at least 3 points from adjacent polygons.. Select the 3 points, make triangle poly and then use the "add point" tool to create an extra point anywhere on one of the triangle's segment that lay in the open. Select the new point.. copy new point and delete the the triangle poly. Paste new point and reconnect the points to make a new quad poly.

You want to move the point further away from the triangle's segment limit? When creating the triangle poly, use the bevel tool with zero shift inset. Or hold down the control key while you use the bevel tool and bevel outwards. This will give you additional geometry that lays on the same axis as the original triangle poly. Add points anywhere on the newly created polys' segments and copy points. Delete all polygons, past the new points.. and reconnect. I hope this helps.

07-11-2004, 05:55 AM
Thanks! It does help. I love those kinds of tricks. :) I'm gonna try 'em both out.