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Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 8:54 am
by mswf
I opened up this topic because I wanted to ask a few questions about how some parts of 3d modelling work. I've searched through a lot of forums on the internet, but I just couldn't find any good answer.
My question is;
Why is it that almost every experienced 3d modeller tries to avoid triangles? I know that they sometimes cause the shading to look weird, but quads sometimes have their "ugly" downside in use as well.

And my second question is (this one would probably has a bit more of a theoretical answer to it); Why do people advise to triangulate models for use in SWBFII? I know what happens when you don't, but I'm wondering just why this is.

I'm asking all these questions because I wan't to indulge myself deeper and deeper in the use of 3d modelling applications and because I ultimately hope to become good enough with it to find an actual job in it (yes, I am aware that there are a lot of people who want this, but I hope to be taken more seriously by knowing some of reasons behind the tips that are presented. I'd also like to express that I have already practiced a lot at making realistic real-life drawings, concept drawings and so on, with the great critical advise from the art teacher at my school.)
I hope I'm not coming over like some sort of streber, I'm just trying to express why I'm asking all these questions :)

Re: Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 9:43 am
by AceMastermind
1. Many modelers stick to quads because they may want or need to increase the subdivisions later to add more detail like round edges or take the model in other sculpting software to produce normal maps etc and quads subdivide better than triangles, tris tend to cause pinching and produce shading artifacts when subdivided. This is not an issue when it comes to game models, tris and/or quads are fine to use on lowpoly game models.

http://www.guerrillacg.org/home/3d-poly ... -artifacts

2. I'm not sure, i've never had to purposely triangulate a model for SWBF2 but if you use MshEx then you have to pre-triangulate since it is required for this utility to function properly, it isn't required by the game though.

Re: Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 9:47 am
by mswf
DarthD.U.C.K. once mentioned (to Codarez, if I remember correctly) that he should make sure to triangulate some small faces on his model because they would otherwise disappear in-game, that's why I asked.
I'm watching the video you linked to, thanks for linking to it.

Re: Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 10:08 am
by AceMastermind
mswf wrote:DarthD.U.C.K. once mentioned (to Codarez, if I remember correctly) that he should make sure to triangulate some small faces on his model because they would otherwise disappear in-game, that's why I asked.
Ok, yeah pre-triangulation was believed to somehow negate the point tolerance witnessed in this game. It can also prevent the computer from performing random triangulation which may produce undesirable results ingame.

Re: Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 5:07 pm
by mswf
So, say I'm going to export my model for SWBFII, it would be advisable to triangulate certain pars on my model were the quads strongly affect the flow of my model. But, were I to use my 3d model in nice renders, I should keep an un-triangulated version. How many parts I triangulate being completely dependent on how I'd the situation.
I hope that I got that right?

Re: Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 5:39 pm
by Maveritchell
mswf wrote:So, say I'm going to export my model for SWBFII, it would be advisable to triangulate certain pars on my model were the quads strongly affect the flow of my model.
By default, I would just not do any work you don't have to do. Manually triangulating parts of a model is an occasional patchwork fix for small polies that may disappear/be unrendered after a munge.

Re: Questions about 3d modelling; mostly about triangles

Posted: Sun Mar 07, 2010 7:27 pm
by FragMe!
Working with quads is preferred yes, tris are find too, from tuts I have seen what you want to avoid is polygons with 5 or more sides* as that can end up with unpredictable results by the game engine. There is and easy tool in XSI to find them.
Select your mesh then on the right side click on where it says Select on the pop up click on Select n Sided Polygons then click on Five Sides or more. It will highlight the polygons that meet that criteria, then just add lines, \ is the shortcut, to the offending polygons until all the 5 sided ones are gone. You may have to repeat the select 5 sided thing once or twice as you go along to confirm or get a reindication that you have gotten rid of them all.

As for why to triangulate, as mentioned it helps on sharply rising edges, like the back of weapons, that would otherwise disappear if you didn't. Once again you do not have to do the whole model just the parts that required it.



*for those that are going to mention it yes I know it goes against the reduce poly count philosophy but I am a control freak and I would rather decide how the shape is handled rather than having the munge engine decide. Since it will triangulate a hexagon into 4 segments by putting in 3 lines anyway why not just put in one line and make it 2 quads. End of FragMe! does things funny rant.

Re: Questions about 3d modelling; mostly about triangles

Posted: Mon Mar 08, 2010 6:32 am
by VF501
Doesn't matter how you Tiragulate n-gons anyways. Game engine only counts tris not n-gons because a Triangle is the smallest sided shape.

Splitting a hexagon into 2 quads, or using three lines from one vertex still makes 6tris.