View Full Version : quads or triangles

05-01-2003, 11:50 AM
Is there any performance difference between rendering triangles or quads? I heard that triangle are more efficient.


05-01-2003, 11:57 AM
Yes it's true. The fastest is TRIANGLE_STRIP.
Graphics cards are optimized to render triangles faster.


05-01-2003, 02:39 PM
Some graphics cards automatically turn each quad into two triangles. Plus, there are three problems with quads in general and neigher apply to triangles.

1. Three points determine a plane so a triangle always has its own plane. You will run into trouble if you try to make a quad where all four points are not on the same plane.

2. A triangle cannot cross over itself. A quad and any other polygon can. This can lead to problems.
[\ /]
[@\ /@]
[@/ \@]
[/ \]

3. A triangle is never concave. Although it is legal, it is not recommended to use concave polygons since there are a lot of priveleges this denies you such as texturing.

05-01-2003, 11:46 PM
Some time ago I made a very simple program to check out that.

It turned out that when there are few vertices, quads are a bit faster (GeForce2, never tested on new cards) but, by increasing the number of vertices, the picture changes.
At higher vertex count, triangles became much faster, up to 673% the quads, even if the extra needed vertices.

Keep in mind however, that it was a "synthetic benchmark", take the results with care.

05-05-2003, 01:51 AM
Think about tri strips, when you are rendering one quad with tristrip you need !4 vertices, 2 quads, !6, 3 quads !8, so lim is going to 2v per quad on higher vertex count http://www.opengl.org/discussion_boards/ubb/biggrin.gif Even Frustum culling can be less efficient than switching to tri strip http://www.opengl.org/discussion_boards/ubb/biggrin.gif