Lee,
I have to say that my understanding of this was the same as Kelvin
explained it. That is the way I would expect it to work. It is
similiar to in music having an "attack" "sustain" "decay".
- John Wright
Starfire Research
"J. Lee Dixon" wrote:
>
> Kelvin,
> This doesn't make sense. The JavaDoc for "Alpha" says:
>
> mode -- This can be set to INCREASING_ENABLE, DECREASING_ENABLE, or the
> Or'ed value of the two. INCREASING_ENABLE activates the increasing Alpha
> parameters listed below; DECREASING_ENABLE activates the decreasing
> Alpha parameters listed below.
>
> This DEFINITELY makes it sound that if I use "DECREASING_ENABLE", that
> the 'increasing Alpha parameters' will be inactive. I think the
> computation of "stopTime" is wrong.
>
> This also doesn't make sense because I was able to make the Alpha
> transition from 1 to 0 several times during a single loop. I am sure
> that this is not the intended behavior of Alpha.
>
> Are the any developers in "Java3D land" that expect this type of
> behavior, and would be affected adversely if it was changed?
>
> -Lee
>
> > -----Original Message-----
> > From: Kelvin Chung [mailto:[EMAIL PROTECTED]]
> > Sent: Tuesday, February 06, 2001 4:51 PM
> > To: [EMAIL PROTECTED]
> > Subject: Re: [JAVA3D] Alpha: Setting mode does not disable use of
> > increasingAlphaDurati on
> >
> >
> > Hi Joel,
> >
> > The stopTime of Alpha is equal to:
> >
> > stopTime = triggerTime + phaseDelayDuration +
> > loopCount* (increasingAlphaDuration+
> > alphaAtOneDuration+
> > decreasingAlphaDuration+
> > alphaAtZeroDuration);
> >
> > When alpha is initialize as
> > Alpha a = new Alpha(1, 2000);
> > the increasingAlphaDuration is set to 2 sec
> > the decreasingAlphaDuration is set to 0 sec
> > stop time is therefore 2 sec.
> >
> > After
> > a.setDecreasingAlphaDuration(1500);
> > a.setMode(Alpha.DECREASING_ENABLE);
> > a.setStartTime(System.currentTimeMillis());
> >
> > the decreasingAlphaDuration is 1.5 sec
> > the above functions did not change increasingAlphaDuration
> > which remains 2 sec. (The spec. did not mention
> > that this will reset increasingAlphaDuration to 0)
> > Thus stop time according to the formula is 3.5 sec
> > which is correct behavior.
> >
> > That's why if we later set
> > a.setIncreasingAlphaDuration(0);
> > the stop time becomes 1.5 sec.
> >
> > Thanks.
> >
> > - Kelvin
> > -----------
> > Java 3D Team
> > Sun Microsystems Inc.
> >
> >
> > >MIME-Version: 1.0
> > >Date: Tue, 6 Feb 2001 14:37:13 -0500
> > >From: "J. Lee Dixon" <[EMAIL PROTECTED]>
> > >Subject: [JAVA3D] Alpha: Setting mode does not disable use of
> > increasingAlphaDurati on
> > >Comments: To: "Java3DBugReporting (E-mail)" <[EMAIL PROTECTED]>
> > >To: [EMAIL PROTECTED]
> > >
> > >JDK 1.3, Java3D v1.2.1Beta1
> > >
> > >In my code, I use the same Alpha for doing a simple 2 second
> > up-ramp (0
> > >to 1)...
> > > Alpha a = new Alpha(1, 2000);
> > >This works fine.
> > >
> > >... then later use the same object to do a simple 1.5sec
> > down ramp (1 to
> > >0)
> > > a.setDecreasingAlphaDuration(1500);
> > > a.setMode(Alpha.DECREASING_ENABLE);
> > > a.setStartTime(System.currentTimeMillis());
> > >
> > >This should disable the "increasing" parameters, but it doesn't. The
> > >alpha lasts for 3.5 seconds, going from 1 to 0 every 1.5 seconds and
> > >jumping to 0 after 3.5 seconds. I've included a snapshot of a graph
> > >showing the trend, and the code used to generate the bug data.
> > >
> > > WORKAROUND:
> > > a.setIncreasingAlphaDuration(0);
> > >
> > > <<graph.jpg>> <<AlphaTest.java>>
> > >
> > >J. Lee Dixon
> > >SAIC - Celebration, FL
> > >407-566-1438
> > >[EMAIL PROTECTED] AOL: LeeOrlando
> > >
> >
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> >
>
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