Message-ID: <3725ABC1.10943C7D@softhome.net>
From: Chris Mears <chris_mears AT softhome DOT net>
X-Mailer: Mozilla 4.04 [en] (Win95; I)
MIME-Version: 1.0
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Fading in/out with 16 bit colours
References: <8D53104ECD0CD211AF4000A0C9D60AE301330CC6 AT probe-2 DOT acclaim-euro DOT net>
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Lines: 30
Date: Tue, 27 Apr 1999 22:21:21 +1000
NNTP-Posting-Host: 139.134.192.84
X-Trace: newsfeeds.bigpond.com 925215347 139.134.192.84 (Tue, 27 Apr 1999 22:15:47 EST)
NNTP-Posting-Date: Tue, 27 Apr 1999 22:15:47 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Shawn Hargreaves wrote:
> 
> Chris Mears writes:
> > In mode 13h, with a 256 colour palette, you could fade the whole screen
> > in and out simply by changing the values in the palette.  And it was
> > fast.  Now, my question:  is there a fast and easy way to achieve the
> > same effect with 16 bit colours?  Using djgpp and allegro, of course.
> 
> There is no such easy way. You have to manually modify every single
> pixel on the screen to make them darker or lighter. The Allegro
> translucency and lighting functions can do this (eg. draw translucent
> black rectangles to darken the screen down), but it will be very
> slow and probably not look too smooth.
> 
> Alternatively you could sacrifice a 128k lookup table, and use that
> to store the color one level darker than each 16 bit pixel, then
> just loop through the screen memory and replace each pixel with the
> version from your table. Allegro won't do that for you, though, and
> it still might be too slow, depending on video resolution and the
> speed of your PC.
> 
> In truecolor modes, it is much more useful to swipe things on and off
> from the side of the screen, rather than trying to fade them :-)
> 
>         Shawn Hargreaves.

I had a feeling it might be that way.  Sliding things from the sides of
the screen sounds good though.  Thank the gods for masked_blit().

Chris