Re: [info-performer] ClipTexture mipmapping algorithms?

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From: Allan Schaffer (allan++at++sgi.com)
Date: 07/14/2003 22:53:26

Hi Curt,

Curt Schroeder wrote:
> OK, to the best of my understanding, ClipTexture mipmapping uses a
> bilinear mipmap algorithm. Is it possible to replace the Performer
> provided algorithm with a better one (trilinear for instance)?
>
> I would like to reduce some of the high frequency "crawl" artifacts that
> are visible when flying over my high resolution (1 m/pixel)
> ClipTexture. I'm currently using Perfomer 2.2.13 in conjunction with
> MultiGen-Paradigm's Vega 3.6.1 on an Onyx2/IR3 platform.

I am talking a little out of my domain but I think the "crawling" may be
something else; it's something that's come up before, look for "jello"
and "wobble" in the mailing list archives.

To answer the question directly: the sampling algorithm is done by the
hardware, so it can't be replaced; however it is my understanding
(subject to correction) that it already uses a trilinear algorithm when
sampling the levels in the clip stack.

Allan 

-- 
Allan Schaffer                                            allan++at++sgi.com
Engr. Manager, Core Rendering                            1-650-933-2160
Silicon Graphics                                     http://www.sgi.com

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