hello , did someone know if it''s better to use triangles insteads of quads with opengl or the computer (opengl or the graphic card) divise itself polygons to make some triangles ??? tanks ! Dominique

as far as I know, most accelerators break quads into two triangles anyway (this is likely the case for all as there is no test to see if the points all lie on the same plane) so it shouldn''t matter which you use, just depends on which one you like best and what format you data''s coming in (if you''re given data in quads might as well draw them as quads rather than making two triangles, just saves time



OGAPO

if u are gonna be using quads be aware of problems that can arise when the card clips it and draws only the one tri
___ ___
|\.| |./|
|_\| |/_|
colour shading results can change cause its interpolation the blend from differnent vertices



http://members.xoom.com/myBollux

Triangles may require 2 more calls, but in the end, anyone that uses quads will be sorry. Quads are auto-triangles, split up by the gfx card, but there is a problem. Many cards are buggy, and distort the quad.

It is also MUCH faster for the card to take in 2 triangles and shove them on the screen then it is to take a quad, split it into 2 triangles, and THEN spit it out.

Triangles = da bomb



L8r,
The Rainmaker
Biendschmofan''s Tutorials Of OpenGL Glander

I''ve red somewhere in the OpenGL Red Book that the fastest primitive to render is the triangle strips, so I think that using tringles as often as possible should be faster than using quads.

My Web Page

Hi,

Quads theoretically should be faster than triangles, assuming non-buggy drivers of course.

This is because only four sets of coordinates have to be sent to the graphics card instead of six (with two triangles) and doesn''t cause as much of a bottleneck on the PCI/AGP bus. Some 3d cards have there rendering rate slowed just waiting for more data to come from the CPU. This is also why Tri-strips are generally the fastest way of rendering things, as they are sent using less data.

If you are worried about buggy drivers, why not send the quad as a small tri-strip instead?

Seeya,

Dan

Ummm guys... The compiler spits out the same info whether you use tris or quads. Basicly it looks like this

push ptr vertex1
push ptr vertex2
push ptr vertex3
call glVertex3f

even if you use QUADS or TRIANGLES the output is the same. I personally use triangles because I won''t want to write a macro to split up the QUADS.

use GL_TRIANGLE_STRIP; its the fastest

it uses only 4 vertexes, too, but it''s faster than quads. This is not a, because the graficscard does this or this blabla.
ITS FASTER USING TRIANGLES, BECAUSE ITS FASTER!!

i just tested it, and its faster...

oh, and, dont look at the asm-code, because this is not a problem by the function-call, its a "problem" of the function, and thats written in the driver.. so, you cant find it in your source

by the way, GL_TRIANGLE_STRIP''s are even more usefull than quads, cause there you could create real strips; like this:

____
|\ |
|_\| //no really nice, the line should go from left to right
|\ |
|_\|

and so on..

but, you arent stupid if you use quads, just not in a large count..

for examples, for menus, you could use quads, without big problems.. just dont create a landscape just done with quads.. thats to slow

we wanna play, not watch the pictures