Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!well!ewhac
From: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Newsgroups: comp.sys.amiga
Subject: Re: Questions about 3-D glasses.
Message-ID: <5115@well.UUCP>
Date: 31 Jan 88 08:17:05 GMT
References: <2444@crash.cts.com>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: Amiga Biotechnology Labs and Nuclear Test Grounds, Nevada.
Lines: 79

In article <2444@crash.cts.com> haitex@pnet01.cts.com (Wade Bickel) writes:
>In a letter crash!eniac.seas.upenn.edu!ranjit (Ranjit Bhatnagar) writes me:
>> 	- why no intuition or multitasking?  Speed isn't really a factor
>> here, because the fastest possible swap between eyes is 30 swaps/second.
>> I'm no expert, but I can think of several ways to do this under multitasking
>> and intuition that at least seem feasible.  For instance...
>> 
>		Essentially, speed is the factor.  In order to create reason-
>	   able 3-D the highest possible switching rate must be maintained.
>	   On most (but not all) Amiga's this is constrained to 60 switches
>	   per second.  Since Intuition's screen update options all require
>	   re-merging of the copper lists, they are out of the question be-
>	   cause they take too long.
>	   
	Sez you!						:-)

> but intuition doesn't have enough to offer to make it worthwhile.  [ ... ]

	Oh, I dunno.  Screen dragging is pretty nice...

>	     Multi-tasking is stopped here because if another task tries to
>	take the screen this server (VBlank) will try to take it back.  [ ... ]

	There is no, repeat, NO excuse for disabling multitasking for this
application.

>> 	+ use a normal interlace screen, and write left-eye pictures on even
>> 	lines and right-eye pictures on odd lines.  [ ... ]
>
>	      This is out of the question for a number of reasons (some of
>	 which you point out.  In particular, it messes up the vertical 
>	 orientation of things just a bit, and of course the drawing functions
>	 are non-functional.
>
	They ARE???  Gee, I guess my 'box' program is working by black magic
then....

>> Though I am quite interested in the use of LCD glasses for 3D, I would 
>> not buy a package with these limitations, and I'm sure others
>> would feel the same way - preferring to wait for a competitor to do the
>> same thing with multi-tasking and intuition compatibility.  [ ... ]

	I guess we have a sale right here....

>	There comes a point of diminishing returns for trying to support
>these features.  [ ... ]

	On the other hand, if you don't support multitasking or Intuition,
you're going to get flamed to a crisp on the Net and elsewhere for it.

	I've written a number of programs utilizing our 3D technology.  The
most esoteric I've gotten is to use raw ViewPorts and pingpong between them
using an interrupt routine.  This in no way impedes multitasking; you
simply can't bring the workbench to the front in this case.

	I've written a program that bounces a ball around in a 3D box.  It
uses an Intuition screen that can be dragged, and uses standard graphics
calls.

	I've written a 3D viewer for Videoscape 3D objects.  It uses
Intuition screens, windows, gadgets, layers, and standard graphics calls.
If the application demanded it, I could have used menus, too.  It multitasks.
It works.

	Mind you, you have to pull some coordinated tricks, but it's
doable.

	We'll be using the Sega glasses, but I'm very interested to see
yours.  Ours should be out Real Soon Now.

	See you on the shelves....			:-)

	(Consider this article the friendly posting that it is.  I'm not
attacking you.  I'm sure you do stuff we don't.)

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Leo L. Schwab -- The Guy in The Cape	ihnp4!ptsfa -\
 \_ -_		Recumbent Bikes:	      dual ---> !{well,unicom}!ewhac
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