PDA

View Full Version : Newbie Question - In game design, can a poly only have three edges, or can it be any?


mitchelhunt
11-03-2006, 06:24 AM
i know its a really newbie question, but im just starting out...

JeffPerryman
11-03-2006, 07:26 AM
Well the term "poly" varies somewhat from software to software, and shop to shop, but for the most part the terms are interchangeable.

I work in 3DS max for example and in there, there are “faces” the triangles you talk of and “Polys” which are quads or two triangles together.

To answer your question, however, at rendertime, in a game, everything is converted into Tri’s as far as I know. There are different methods out there that work on strips of tri’s or in some cases just count the number of verts in a model. But if I understand what you are asking, yes a "poly" in the game world, is only 3 sides.


I hope that helps

doylle
11-03-2006, 08:05 AM
This is a very interesting question. Because, alot of people are asking about polycount when they probably mean triangle count. (if we're talking game design).

i did a little test in 3dsMax. drew a spline with 8 vertexes, and converted it to editable poly.

http://img81.imageshack.us/img81/6617/polyfy0.jpg

http://img157.imageshack.us/img157/7605/trisgz8.jpg

so, basicly what does max do, Whatever lies within a number of edges, is counted as 1 poly. Doesn't matter how many edges there are. If you count triangles, then max hypothetically connects vertexes so that all the polys have exactly 3 edges, and counts again.

and of course, the triangle count is what matters in game design (as far as my knowledge goes)

NikLG
11-03-2006, 10:31 AM
That being said, some game engines / consoles ( if not all ) prefer quads . Though everything is made of tris, if you model in quads as far as possible and set the mesh and UVs up to 'strip' nicely they can be rendered quicker. As far as I know it's because the engine knows where the first 3 points of the first quad are ( that'd be a tri ) and uses the first point of the next quad to know where the fourth point of the previous quad is ( if that makes sense ). So you are effectively getting 2 tris drawn for the price of one. If you break up the stripping though, you're back to having to calculate the position of all points which defeats the object of modelling in quads.

Nik

Johny
11-03-2006, 11:18 AM
All game engines convert the models to triangles , so every 5 sided or 6 sided gets converted to triangles .
Still , when you model i would get past the quads ( except for cilinders, etc ) character wise, having a clean mesh helps you see the edge flow and deformation , but that doesnt mean you cant have tris , you just have to use it friendly to create a good edge flow :)

mitchelhunt
11-05-2006, 02:55 AM
Thanks for all of your answers, they really help alot!

JuddWack
11-05-2006, 02:03 PM
Are you confused about the mathmatical properties of a poly or how to optomize poly usage for game design? I was writing up a description of what a poly actually is because no one has really included one, but that's stuff that should be learned in a highschool education. These damn chinese kids are learning it in 3rd grade.

mitchelhunt
11-05-2006, 04:22 PM
Well I am in highschool, but I know what a polygon is, I learned that in...5th grade I think. But we did go over it again in math. Anyway...yeah I was just wondering about the game design aspect. But I guess the end result is always triangles.

CGTalk Moderation
11-05-2006, 04:22 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.