Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-tis!ames!oliveb!sun!kjeld@mcopn1.csc.ti.com
From: kjeld@mcopn1.csc.ti.com
Newsgroups: comp.sys.mac.hypercard
Subject: RE: Visual effects on overhead projectors
Message-ID: <81809@sun.uucp>
Date: 15 Dec 88 17:39:22 GMT
Sender: news@sun.uucp
Distribution: comp
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Approved: hyper-hackers%plaid@sun.com

Jakob Nielsen Tech Univ of Denmark writes
>...
>Last week I gave my tutorial at the ACM Conf. on Document Processing
>where they had a transviewer from Sharp - and it worked with the visual
>effects||

The visual effects have always been there, you just haven't seen them.
Or is that a philosophical conflict in terms?

>I don't know what the  factors are which determine whether HyperCard
>visual effects are shown on a projected screen image. But until
>HyperCard is changed to use visual effects on all types of screens,
>this should be a parameter taken into account when buying screen
>projection hardware for your Mac.

This is not a function of HyperCard.  It is a function of the screen.
Liquid Crystal Displays are inherently slow.  SuperTwist displays yield
greater contrast.  Nematic/Cholesteric (spelling?) transition yields a
faster display.  Some of the new displays have both features.  Sharp has
such a display.  It can change the brightness of a pixel in about 1/9th
of a second.  This means that visual effects that are slower than about
nine frames per second will show.  Faster effects will not.  There are
faster displays.  Either Kodak or Sony (don't remember which) has a 14
frame per second display.  This is about the best you can currently expect.
Some of the slower displays have better contrast ratio.  In either MacWorld
or MacUser (don't remember which) this month, there is a comparison of
some of the available displays.

For some of the slower displays, try doing your effects "very slowly"
and see if they don't show up.  There is nothing the authors of HyperCard
can do to fix this problem.  It is a hardware problem that is out of
Apple's hands.

Kurt Christensen
Lowly Engineer @ Texas Instruments
President/Chief Technical Officer @ Apeiron
One of "The Rest of Us" @ Planet Earth
KJELD%MCOPN1@EG.TI.COM

Disclaimer: My opinions expressed here are my own and do not reflect those
            of Texas Instruments Incorporated.  They do, however, reflect
            those of Apeiron, since my partners believe everything I say.
            The Rest of Us will have to speak for them selves.
***