The difference between a POLY and a TRI
by Paul Fassett · in General Discussion · 02/04/2005 (12:19 pm) · 19 replies
I have always been of the belief that a polygon is a square, and a tri is a triangle. Sometimes it seems that people get polygon mixed up with tris and tend to think of them the same way. Like for instance if I say I completed my model, and it is only 2200 polygons, then you take it into blender and it looses the square normals and reports back 4400 what is the deal with that. Does that mean 4400 tris, or does max measure polys different?
I thought that a polygon consists of 2 tris. Is that true? And when someone sets there poly cap to 2200, doesn't that mean the cap would be 4400 tris? This has always bothered me. Can someone clear up the definition for me and everyone else who may not be sure about this. I'm pretty sure I'm right, but I want to make sure.
I thought that a polygon consists of 2 tris. Is that true? And when someone sets there poly cap to 2200, doesn't that mean the cap would be 4400 tris? This has always bothered me. Can someone clear up the definition for me and everyone else who may not be sure about this. I'm pretty sure I'm right, but I want to make sure.
#2
02/04/2005 (12:25 pm)
Pol
#3
02/04/2005 (12:26 pm)
Ok so how does max measure polys? By the quad? Because once it looses the normal or whatever and gets imported into another program the count usually doubles, and thats where it gets confusing. 
#4
02/04/2005 (12:28 pm)
You are, in fact, not right. Depending on how it converts polys to triangle strips, and how many verts are in those polygons, there is no way to say for X polys you will have Y triangles.
#5
A lot of the tools in MAX tend to produce quads, though, so all the faces/polys you're working with could actually be quads. You can't depend on the polygon count always being (Triangles / 2), but it makes a fairly decent approximation most of the time.
02/04/2005 (12:29 pm)
If I recall correctly, Max counts polygons as polygons, not necessarily triangles or quads.A lot of the tools in MAX tend to produce quads, though, so all the faces/polys you're working with could actually be quads. You can't depend on the polygon count always being (Triangles / 2), but it makes a fairly decent approximation most of the time.
#6
02/04/2005 (12:31 pm)
Ok, so if you are the most stupendous modeler of all and your entire model is comprised of quads, then you just double the poly count to get your tri count. So I could usually double my count and get a fairly approximate number of what my actual count is. Thank you guys for all the quick responses. This will come in handy for the rest of our design team. 
#7
This is most likely what is happening in this case...
02/04/2005 (12:32 pm)
Double counts are usually due to a triangle becoming double sided in the translation process, meaning that each triangle becomes 2 triangles. This is most likely what is happening in this case...
#8
02/04/2005 (12:34 pm)
The show tool reports how many detail polys are in the model. I would expect that to be the most accurate way since it's post export.
#9
02/04/2005 (12:37 pm)
@Nicolas: Ok that makes sense then as the count only jumps when it gets exported to .3ds.
#10
Maya counts polys by n-sided faces, a more true definition of "polygon".
02/04/2005 (12:39 pm)
Max counts polys by triangles.Maya counts polys by n-sided faces, a more true definition of "polygon".
#11
an 'Editable mesh' which is more suited to triangles, and i think returns an actualy triangle count in properties/Faces. edges can be hidden to give the impression of polygons, but it still counts each triangle as a face.
then theres 'editable poly' which can use many sided polygons, this does count the number of polygons as faces.
eg ; my Editable Poly currently has 455 'faces'.
if i convert it to an Editable Mesh it now says 803, the correct triangle count
02/04/2005 (1:04 pm)
From max 4 onwards (i think) theres 2 types of 'mesh'.an 'Editable mesh' which is more suited to triangles, and i think returns an actualy triangle count in properties/Faces. edges can be hidden to give the impression of polygons, but it still counts each triangle as a face.
then theres 'editable poly' which can use many sided polygons, this does count the number of polygons as faces.
eg ; my Editable Poly currently has 455 'faces'.
if i convert it to an Editable Mesh it now says 803, the correct triangle count
#12
install it, hit 7, and select your mesh(es) it gives correct tri count for editable mesh AND editable poly in the top left corner of the active viewport, as well as a few other stats.
02/04/2005 (1:32 pm)
For max, I use this poly counter script: www.juantwo.com/scripts/Macro_PolyCounter.zipinstall it, hit 7, and select your mesh(es) it gives correct tri count for editable mesh AND editable poly in the top left corner of the active viewport, as well as a few other stats.
#13
02/04/2005 (9:07 pm)
Think polys in max are 2 tris with thir interior edge hidden as in Max 7 when you click on the turn button in edit poly all the hidden edges become visible. Usually max exporters export tri's regardless of what you model anyway. You can allways model with patches to get real quads, but I don't know of an exporter that exports quads directly.
#14
If you model with patches, they will be exported as tris at whatever resolution you have the patch subdivision set to.
02/04/2005 (9:48 pm)
I have the 'show all edges' command set up in my right click menu when modeling. If you are in edit poly, it will show the count for polys as 'polys'.. the TGE uses tris.. when someone refers to poly count engine side, it is in tris.. so best to check the counts in max/maya/LW in tris to get an accurate count. Note also that even though it is easier to model with polys, it is important to pay attention to the 'hidden' edges so that you get good tri-strips. If you model with patches, they will be exported as tris at whatever resolution you have the patch subdivision set to.
#15
02/05/2005 (2:00 am)
Paul, I tried to email you back but it bounced, drop me a line from another email email when you get a chance.
#16
02/05/2005 (1:24 pm)
Yes, Paul- definitely e-mail Gonzo from a different account as soon as you get a chance. That explains a lot.
#17
Thats my new email address. I will email you tonight.
02/05/2005 (2:33 pm)
Paul_fassett@yahoo.comThats my new email address. I will email you tonight.
#18
02/05/2005 (2:39 pm)
Also you often have to edit the triangulation in order to get normal smoothing to behave with dynamic lighting the way you want it to in order to avoidugly artifacts across a smooth surface.
#19
09/19/2005 (5:05 pm)
So whats the proper way to generate tri-strips? And what makes up a tri-strip? Is one quad a " tri-strip "? Thanks for any help concerning this matter as I am trying to figure out the science behind all of this. 
Torque Owner Mz
When people are specifically talking about 'squares' in computer graphics, they usually say Quads, not Polys.
It's not common to deal in real, non-triangle polygons in real time graphics - they probably mean to say triangles when you see the word 'polygon' in people's requirements for a model.
Since polygons can have any number of vertices, a single polygon could equate to quite a large number of triangles.