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From: brianw@microsoft.UUCP (Brian Willoughby)
Newsgroups: comp.sys.apple
Subject: Re: Apple IIgs SHR fade
Summary: Idea for fade algorithm
Keywords: fade, IIgs, SHR
Message-ID: <5770@microsoft.UUCP>
Date: 21 May 89 23:22:20 GMT
References: <11472@bloom-beacon.MIT.EDU> <30927@apple.Apple.COM> <2808@puff.cs.wisc.edu> <2335@wpi.wpi.edu>
Reply-To: brianw@microsoft.UUCP (Brian Willoughby)
Distribution: usa
Organization: Microsoft Corp., Redmond WA
Lines: 22

In article <2335@wpi.wpi.edu> dseah@wpi.wpi.edu (David I Seah) writes:
>I was wondering if that algorithm would cause color distortion myself.  Would
>you have to lower each one of red,green, and blue color components
>proportionally so that they all zeroed out at the same time?
>
>In a word, please post it! :)
>
>Dave Seah (dseah@wpi.wpi.edu)

Here is an idea for a fade algorithm that should be fairly simple:
Seems like you could look at the pallette color register that you want to
reduce, and then choose the component with the lowest value. Then
multiply each of the RGB components by a fraction which would effectively
decrement the smallest component. For example. if R=100, B=78 and G=90,
then multiply each component by 77/78. Of course, since I don't have a GS,
I can't predict how much rounding error would mess up this approach.

Perhaps someone could send me a II GS, and I could try it out?

Brian Willoughby                        ...!uw-beaver!microsoft!brianw
                or                      microsoft!brianw@uunet.UU.NET
                or just                 brianw@microsoft.UUCP