XS1100

05-01-2003, 11:50 AM

Is there any performance difference between rendering triangles or quads? I heard that triangle are more efficient.

Thanks

Thanks

View Full Version : quads or triangles

XS1100

05-01-2003, 11:50 AM

Is there any performance difference between rendering triangles or quads? I heard that triangle are more efficient.

Thanks

Thanks

yaro_dup1

05-01-2003, 11:57 AM

Yes it's true. The fastest is TRIANGLE_STRIP.

Graphics cards are optimized to render triangles faster.

Cheers,

yaro

Graphics cards are optimized to render triangles faster.

Cheers,

yaro

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.

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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.

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.

Obli

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.

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.

M/\dm/\n

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

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