View Full Version : Tri's VS Quads

06 June 2009, 05:12 AM
OKAY I don't know if I'm posting in the wrong section or not, I don't run around and post on forums much But I suppose I should go ahead with my question. I know its kinda noobish but, I have this buzzing confusion; How come video game models are usually in Tri's (Triangles) whereas when we model it should be in quads? Yes running around in topology threads and researching about it I learned quads help keep the flow of topology and Tris screw up animation if its in a bendable area. I'm just confused as to how come in video games alot of the models are in Tris (some have quads with triangles wich perplexes me even more). I model alot and of course I avoid triangles as much as possible when modeling a human being, but when I go reference hunting and look at references, even some of any human mesh given, they are in triangles. Does anyone have a reasonable explanation for this so I can clear up some of this funky smoke? :shrug:

06 June 2009, 11:11 AM
First thing to know is, that ALL models are made out of tris. In every modeling pakage. The internal triangulation is just hidden. (You can try this...create a quad and move one vertex downwards. You'll notice a invisible edge, where the quad is folded...)

When creating a game model, you want to watch the polycount (number of tris). To get most control over your model with the lowest polycount, you model in tris. You can, of course, model in quads and let the program do the triangulation automatically, but in some areas this triangulation might not be what you want.

AFAIK, most modellers model in quads (or even NGons, where you can get away with it) and then do the triangulation for problem areas by hand and let the programm handle the rest (at least that's what I'd do ;)).

07 July 2009, 06:09 AM
The games we make at work are typically for the Nintendo DS
And on this platform there are only a certain amount of polys that can be used on screen at a time.
So our models tend to be a blend of tris and quads.
Say you have a 250 poly limit per character, (A 250 poly quad model is a 500 poly tri model) obviously you'd want to use quads right? you maximize the poly limit by using quads.
But sometimes the quads end up being non-planar and drop out on screen (end up looking like holes in the characters) so they have to either be manually flattened or triangulated to be fixed.

As for workflow, most of our artists build characters in quads (mainly because it's just easier) and then triangulate and reduce the character where necessary.

As for the model below, I imagine the reason that it is fully triangulated is because 1. the engine can only handle tri's, or 2. to avoid any potential problems like the poly drop out mentioned above.
The model in the image could have been triangulated more efficiently - but it looks as though they dont really have a poly limit to work within.

My advice to you is to model in quads and don't worry about triangulating your models, and don't be restricted to just quads, it's nice to have all quads but triangles aren't the abomination that people make them out to be.

Hope this helps!

07 July 2009, 09:33 AM
The simple answer to your question is poly count.

Games characters and model have a restricted polycount if you make it too realistic then the games will run sluggish and no one wants a slow and sluggish game even with the pretty graphics. PS had i think 500 polycount as their main character. PS2 was something like 5000.

As for a technical answer. When meshes are being process, ( i.e rendered to screen) it is broken down to the smallest polygon which is a trangle. This is the fastest way to process meshes before it gets displayed on screen.

However in movies they are not so limited because optimization is not as strict like the console platforms. So they can push out the best quality without having this worry on their minds.

Hope that answers your question or at least makes thing clearer.

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07 July 2009, 09:33 AM
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