PDA

View Full Version : Do I need to use Triangles?


lazzhar
03-06-2004, 06:54 PM
Hi,


I've never tryed modeling for games, but recently I've been involved in a game project, well.. I'm kinda confused because I never modeled for games.

I've seen lot of low poly models designed for games and it seems modelers like using triangles too much.
So my question is: May I use quad poly? or for game engines I have to triangulate each polygon?

ps: I didnt find where to post this ! Maybe there is other place where should i post a quetion about games..

Staffan Norling
03-06-2004, 07:20 PM
Well...your graphics card can only draw triangles, so yes, you have to use them. Don't worry about that though, the exporter will probably handle the triangulation for you. Modelling in quads is preferred becouse you'll get both better geometry flow and triangle stripping that way. Check the stiky thread about tips and trick in this forum for info...

commy
03-06-2004, 07:28 PM
modeling in quads is not prefered at all quads should be used on areas where the diagonal cross edge doesnt need to be defined ie planar or flat quads, tri's should be used in areas of deformation like faces etc to preserve symetry and help the flow. u cna model all in quads and then hand triangulate the faces etc if u want thats fine but done leave them as quads.

btw u cant "use tri's too much" everything is tri's even hi poly models the fact is on hipoly work with smoothing and subdivision most quads are small and planar so hand triangulation isnt needed

quads are easier to work with but u must hand triangulate curvy surfaces to ensure the geometry flows correctly

lazzhar
03-06-2004, 07:50 PM
Thanks, I'm using Maya and I could show in the ViewPorts the Number of faces used in my model. Is it what guys in games call polygons? (ie: 3000 poly..etc)

I could use Triangulate frunction in Maya but the number of faces would be X2.

Edit: I've found the theard in the top and it seems answering all my question. thanks for your help.

Matt
03-06-2004, 09:36 PM
The number of faces are X2 anyway. Your graphics card draws triangles, not quads.

mtague
03-07-2004, 01:03 AM
I was wondering about this too, and I'm still a bit confused.

So if the exporter does the triangulation for me, it's all ok?

And if I wanted to hand triangulate, I should do parts like the character's face and such?

Modeling for games at times seem harder than just for fun.

3bleadpencil
03-07-2004, 01:40 AM
Commy:...that's interesting...I never knew that.....so I should (when needed triangulate areas of deformation.....can I assume that such areas would be the knees/elbows/ neckarea????...pretty much anything that bends?
...if anyone can illustrate this with wire frames that would be greatly appreciated cause I've been working totally in Quads.
Would totally be helpful for newbies to understand such an issue.
Regards To the Community
Carlo

Dargon
03-07-2004, 02:19 AM
I guess what to keep in mind is that the game engine will use triangles no matter what you do.

So, if you want to make sure that it breaks one way instead of the other, break it yourself.

Also, there's no reason to avoid triangles for low poly, because it will end up that way anyway, and maybe a little reason to avoid quads, because the exporter may make different decisions than you would of.

I often use quads and triangles, only quads when it's not going to make a difference either way. Then, before handing in my model to the appropriate agent, create a triangulated version.

Just never have any more than 4 sides (n-sided polygons) anywhere on your model. By rule of thumb, these will almost always get split in the worst way possible, and hardly ever in the way that makes sense. Plus it's just bad modeling habit.

Dargon
03-07-2004, 02:22 AM
Originally posted by lazzhar
Thanks, I'm using Maya and I could show in the ViewPorts the Number of faces used in my model. Is it what guys in games call polygons? (ie: 3000 poly..etc)

I could use Triangulate frunction in Maya but the number of faces would be X2.


Oh yeah, a P.S. ...

Download bonus game or bonus tools for Maya. It comes with a triangle count HUD, plus a whole helluva lot of great poly tools, without which, Maya's poly workflow is limited.

(get it for free from alias's website)

lazzhar
03-07-2004, 05:50 PM
Thanks for help
I'm still wondering about the right workflow used when modeling for games. All we know that there is a limited PolyCount that you should consider, so when you model in Maya (without BonusTools) you should always think in counting the triangles not the quads.
I started my first lowpoly model, and I want you tell me if I'm wrong when modeling in quadri-Polygons? You could see that it has 1270 faces and when triangulating it would become ~3000 tri.

I've seen most recent Characters using ~3000 tri, do they model this way then triangulate or they aoid quads from the begining?
http://lazzhar.arabcg.com/odin/lowpolychartri.gif

3bleadpencil
03-07-2004, 06:05 PM
Lazzhar:...I was wondering that too....do the pros model in quads first then do the triangulation afterwards?..
Hope someone can shed more light on this because is a major issue in my 3d class. So far...no clear answers...
Regards
C.

Dargon
03-07-2004, 06:34 PM
Originally posted by 3bleadpencil
Lazzhar:...I was wondering that too....do the pros model in quads first then do the triangulation afterwards?..
Hope someone can shed more light on this because is a major issue in my 3d class. So far...no clear answers...
Regards
C.

Well, as a pro, I'll step in...

I model in mostly quads, but I don't care if I end up with a few triangles.

This changes slightly depending on your polycount. The lower it is, the more careful you'll have to be, and the more tricks you'll have to pull to get anything worthwhile.

For polycounts between 500 tris - 1200 tris, I'd say more than likely you'll be modeling in triangles. Each facet of the character will be so important, you can't leave it up to chance how a quad will get divided.

That also opens up the topic of modeling techniques - sometimes it's not a good idea to have all your objects line up like quads promote. Quads will have a tendency to straighten out your lines and deformations. Another technique is geodesic modeling, always modeling with triangles aranged in hexes. It gives better round forms, and better organic deformation. If modeling this way, you never even touch quads.

I do tend to do a lot of quads, and for wireframe shots, if it's modeled in quads, I like to see it as such. It's a lot easier to tell what's going on, and where edgeloops are going when in quads. I just don't avoid triangles. I do avoid n-sided polys, though.

commy
03-07-2004, 06:43 PM
ok kiddies :)

lesson 1)it will not "end up" as triangles its has been and always shall be triangles! it may look like a quad or an n-sided poly but it is infact a group of triangles, max users can see these as faces (the dotted lines within ure polys) and im sure other programs can too, if u do not specify where the edges lie the computer adds them itself! u just cant see them!

lesson2) its not a question of wanting or not wanting to hand triangulate, when u export ure model it gets triangulated this means any 4 or more sides polys, there faces become fixed, it draws the edge line i mentioned above in as a solid edge. hand triangulation is done on areas where u want the edge to lie a certain way.

lesson 3) a triangle is always flat, if u dont believe me make a triangle in ure program and try to make the surface non planar, u cant, this is why triangles are the base of all 3d, they are always flat! smoothing is an algorythm that controls the shading across polys the actual polys will always be flat the viewport/engine just uses vertex info to generate smooth shading across polygons

lesson 4) quads can be non planar, draw a grid and raise 2 oposite edges so u get a V shape, now try drawing from 1 raised point to another, now delete that edge and draw across the 2 bottom points, u see the difference? this is the reason u hand triangulate areas such as faces etc to ensure u get a continous surface! (example below both grids share identical points but the hand triangulation has radicaly altered their apearance!) if u dont hand triangulate the converter may pick either method, on areas where shape is important and u want a flowing surface dont trust the converter to choose the right method!

http://www.matthewdickinson.com/files/triexample.jpg

lesson 5) theres no need to model in either quads or polys exclusivly, what u should aim to do is to have the best use of polys on ure model, if somewhere doesnt need detail, dont add it! always use ure poly budget wisely and dont forget to add enough polys to deformable areas such as knees elbows etc, low poly modeling is balance between model and textures

think thats everything really maybe some more ill add later :)

BurrowingDuck
03-07-2004, 06:54 PM
I prefer modeling in both at once. If I'm trying to make an irregular shape, I use triangles to try and minimize polycount.

Staffan Norling
03-08-2004, 11:04 AM
Originally posted by 3bleadpencil
Lazzhar:...I was wondering that too....do the pros model in quads first then do the triangulation afterwards?..
Hope someone can shed more light on this because is a major issue in my 3d class. So far...no clear answers...
Regards
C.

When i create characters, i mostly model in quads. Ofcourse, ending up with a few triangles is inevitable. I keep the quads during the uv-mapping process becouse it makes it less messy.
then i triangulate to create triangles that are all aimed in the same direction. It's important (in maya, at least) to triangulate before you rig the character. Otherwise, maya's own triangulation proces will kick in and flip edges while you deform the model.

When modelling props and levels, i don't care much about number of corners in my polygons...i like to keep then large to simplify the uv-mapping process. Then i triangulate and split polygons before the export.

Try to avoid the built-in triangulation tools (in maya atleast), it is made to triangulate complex high-polygon models, not game models. It will try to triangulate your model for maximum continuity, wich is not always prefered for game models, since it will make it difficult for the triangle-stripping process of the exporter and make your model draw slower in the game engine.

Triangulating by hand or using a plugins that triangulates all polygons in the same direction is prefered (but watchout, this will create unacceptable continuity in som cases, and you'll have to go trough your model and fix that by hand).

Staffan Norling
03-08-2004, 11:08 AM
Originally posted by lazzhar
Thanks for help
I'm still wondering about the right workflow used when modeling for games. All we know that there is a limited PolyCount that you should consider, so when you model in Maya (without BonusTools) you should always think in counting the triangles not the quads.
I started my first lowpoly model, and I want you tell me if I'm wrong when modeling in quadri-Polygons? You could see that it has 1270 faces and when triangulating it would become ~3000 tri.

I've seen most recent Characters using ~3000 tri, do they model this way then triangulate or they aoid quads from the begining?
http://lazzhar.arabcg.com/odin/lowpolychartri.gif

The model looks really good, both in aspects of triangle-strip friendliness and continuity. I don't thing it will deform well, though. Shoulders, knees and elbows should be built differently if you want to avoid a painful rigging process. Check threads of other character modelers in this forum to get an idea of how to fix it...

commy
03-08-2004, 02:34 PM
also u may want to consider using the polys uve put into the model, its very flat linear not very exciting, u have a fairly large poly count add some interest and funk to the model, make his pants slightly more flared or bell bottomed add some suggestion of muscle to his arms and chest, as steffan mentioned ure shoulder/elbow/knee areas are going to be a pain, try not to use such a rigid grid like approach and model with the form in mind, u seem to have done it on the face alot better than the body from what i can see

Staffan Norling
03-08-2004, 03:20 PM
The top of the head seams a little too complex too...the area above the eyes is a typical area where you have to accept lots of triangles and bad triangle stripping..

lazzhar
03-09-2004, 07:24 PM
Thanks,
I've just started deleting edges from a highpoly head I modeled before thinking in this idea. This model is meant to be a basic shape I'd like to use as a starting point for eventual models. I just wished to ask about that issue before going far and maybe in the wrong direction.
But I'm still wondering what to do right now? triangulate it then add details or what ?

Staffan Norling
03-10-2004, 09:48 AM
It's obviously up to you to decide that, since we all seams to have different oppinions. Find a workflow that works for you. Just remember to riangulate before you rig the character. :)

CGTalk Moderation
01-17-2006, 03:00 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.