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List:       mesa3d-users
Subject:    Re: [Mesa3d-users] Efficient Drawings
From:       "Brian Paul" <brian.paul () tungstengraphics ! com>
Date:       2007-08-15 11:03:34
Message-ID: 833c00720708150403k14da9a00lfc0da0284639419a () mail ! gmail ! com
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On 8/14/07, Kent Eschenberg <eschenbe@psc.edu> wrote:
> Note: Mesa users, please ignore the VTK- and ParaView-specific questions.
>
> vtkStructuredGrid can blank cells and vertexes but vtkDataSetSurfaceFilter pays
> no attention. I've fixed that on our local version with a new section of code
> that generates quads. This filter could generate many millions of quads so it
> makes sense to think about efficiency.
>
> Do modern graphics cards and Mesa draw quads as fast as the equivalent two
> triangles?

Every OpenGL implementation (both hw and sw) that I know of draws
quads as two triangles.


> If I generate triangles do modern graphics cards and Mesa work that much faster
> using triangle strips?

Tri strips should probably be used whenever possible instead of
separate triangles since the ratio of triangles to vertices is higher
(basically 1:1 vs. 1:3).

But if rendering time is dominated by rasterization, strips vs.
separate prims won't make much difference.

As usual, this all depends on exactly what you're doing and the best
answers are gained through experimentation.

> If I generate strips how does this interact with the ParaView option to
> generate triangle strips (under "3D View Properties" in 2.6.1)?
>
> TIA!
> Kent
> Pittsburgh Supercomputing Center

-Brian

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