Re: Scale in View Matrix.

New Message Reply Date view Thread view Subject view Author view

Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Fri, 14 Feb 1997 15:39:49 +0000


The clip stays in the same place but the model will be scaled.

You scale < 1 the world gets smaller around the eye and so the
near clip appears more distant but it isn't.

This will also affect Z values and fog.

It doesn't surprise me that the performer cull doesn't look for scale in
the channel matrix, but this is just a performer implementation issue rather
than a fundamental discovery.

Cheers,
Angus.

On Feb 13, 2:58pm, Andrew Ng wrote:
> Subject: Scale in View Matrix.
> Hi there,
>
> Has anyone had any experience of using a uniform scale in the view matrix
> of a pfChannel?
>
> I've been playing around with this and it appears to have some strange and
> unexpected effects on the near clip plane. I've been using pfChanViewMat to
> set the pfChannel matrix.
>
> If I use a scale of < 1, then objects appear to clip sooner than I would
> have expected. If I use a scale of > 1, then objects don't appear to clip
> as soon as I would expect, in fact sometimes the objects are culled out
> before they are clipped.
>
> I'm using Performer 2.0.2 and IRIX 6.2 on an Indigo 2 Max Impact.
>
> I'd be grateful for any ideas or suggestions.
>
> Thanks.
> ------------------------------------------------------------------------
> ------
> Andrew Ng (Software Engineer)
> Division Limited, 19 Apex Court, Email:
> nga++at++division.co.uk
> Woodlands, Almondsbury. Tel: +44 (0)1454
> 615554
> Bristol BS12 4JT. Fax: +44 (0)1454 61
> 5532
>
>
> =======================================================================
> List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
> Submissions: info-performer++at++sgi.com
> Admin. requests: info-performer-request++at++sgi.com
>-- End of excerpt from Andrew Ng

=======================================================================
List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
            Submissions: info-performer++at++sgi.com
        Admin. requests: info-performer-request++at++sgi.com


New Message Reply Date view Thread view Subject view Author view

This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:54:39 PDT

This message has been cleansed for anti-spam protection. Replace '++at++' in any mail addresses with the '@' symbol.