View Full Version : polygons vs. triangles
phantomgti2 05072002, 02:36 AM hey everyone!
i got a really simple question that is kinda confusing me.
what's the difference between polygon and triangle counts?
thanks. T


FBMachine
05072002, 03:46 AM
Triangles are polygons, but polygons aren't necessarily triangles. All polygons that have more than 3 sides can be broken down into triangles. The polygon count is the total number of all polygons ( including triangles ), while for the triangle count, the polygons are broken down into triangles, so it's not longer a mix of nsided polygons and triangles, it's all triangles. For instance, say there is 1 quad, and 1 triangle in a scene. The poly count would be 2, but the triangle count would be 3 because a quad is broken down into 2 triangles.
Dan
Katachi
05072002, 09:49 PM
@@Triangles are polygons, but polygons aren't necessarily triangles.@@
Wrong! Polygons are always triangles. Just because the application shows you a nsided polygon it doesnīt mean it isnīt a triangle. ;) Normally nsided polygons do not exist. You can see it as a fake. Programmers should know it! :) This is a shakedown!!! :))
Every Polygon that is "not" a triangle are several triangles.
Cheers
FBMachine
05072002, 11:21 PM
First, I was talking about polygons in a geometrical sense, which certainly do exist you goofball. :p I am a programmer as a matter of fact, and I know that polygons are triangulated before they are rendered, but that doesn't mean nsided polygons aren't really there, as far as the storage of the geometry in the file goes, there are nsided polygons.
Dan
Katachi
05072002, 11:35 PM
Hi,
@@but that doesn't mean nsided polygons aren't really there@@
Oh yes, thatīs exactly what it means! :p
@@as far as the storage of the geometry in the file goes, there are nsided polygons.@@
Thatīs partly correct, but the storage of the geometry in the file is just a reference for the programm. The real code is of course converted by the app internally. And the app does not know any nsided polys at all! Conclusion: nsided polygons do not exist! :applause:
But I guess thatīs not the kind of answer phantomgti2 wanted to have! :p
Of Course I know what you wanted to say! :)
Cheers
FBMachine
05072002, 11:55 PM
"And the app does not know any nsided polys at all!" Here you are wrong. Programs do some operations on nsided polygons, it does not necessarily triangulate for everything. Triangulation is only good for certain operations. Don't make me bust out my graphics programming books. :)
Dan
LFShade
05082002, 12:07 AM
Best answer to the question:
Triangles are just that  3sided faces. Polygons can have 3 or more faces. Some applications which distinguish between trianglebased geometry and polygonal geometry will report polygon count differently between these two object types. 3dsmax, for instance, will always report the number of triangles on an Editable Mesh object even when it appears in the viewports to have faces with greater than 3 sides. But for an Editable Poly object, Max will report the number of true polygons.
The difference may only be one of semantics, but it becomes important if you're making models for a game, since game engines triangulate everything. If you're working with nsided faces in your modeling package, you'll still need to keep the triangle count in mind so that you don't exceed your geometry budgets for the target application.
FBMachine
05082002, 12:16 AM
phantomgti2 skip all the other replies and just read LFShade's, it's much clearer.
Dan:thumbsup:
Katachi
05082002, 12:23 AM
graphics books? Got three of them always besides me! :)
But I agree, just read the answer of LFShade. :wavey:
We are just talking ****! :scream:
Cheers
LFShade
05082002, 12:58 AM
Oh yeah, forgot to mention. Here's a rule of thumb for the triangulation of polys with greater than 3 sides:
A polygon with n sides will break down into n2 triangles.
phantomgti2
05082002, 03:18 AM
thanks guys for all your input.
windarr
05082002, 06:36 PM
Originally posted by LFShade
Triangles are just that  3sided faces. Polygons can have 3 or more faces.
I believe you mean Polygons can have 3 or more sides.
;)
LFShade
05082002, 10:17 PM
Thanks. I really need to read over my scribblings before I post them:thumbsup:
windarr
05092002, 05:35 AM
HA HA HA LOL. Yeah I have to be careful too.
:)
CGTalk Moderation
01132006, 06:00 AM
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.