Re: A82: Contrast

Re: A82: Contrast

• To: assembly-82@lists.ticalc.org
• Subject: Re: A82: Contrast
• From: "Thomas J. Hruska" <thruska@tir.com>
• Date: Wed, 20 Aug 1997 16:53:31 -0400
• In-Reply-To: <3.0.1.32.19970820101831.007dc640@mail.geocities.com>
• References: <3.0.1.32.19970820181122.00795b50@m1.314.telia.com>
• Reply-To: assembly-82@lists.ticalc.org

At 10:18 AM 8/20/97 -0700, you wrote:
>At 06:11 PM 8/20/97 +0200, you wrote:
>>Hi!
>>I want to add a flashing effect to my game, and I figure that using the
>>contrast would be the most effective way. Does anyone have any routine for
>>this (I have ROM version 18)?
>>
>>
>>Erik 

"Flashing effects" are annoying (at least I think so) unless you can
implement them with the user in mind.  If you do this, you have to also
detect what contrast setting the user currently has or your game will be
either too dim/dark.  The only way to do this is by using the contrast
memory address.

>Check 82-ports.txt for the cool way to do it, there is also a mem address
>that holds the contrast, I've never messed much with this though. A nice
>flashing effect can be added by going through GRAPH_MEM and xor'ing each
>byte with $ff, which will reverse (black pixels->white, white->black) the
>screen, then do that again to restore it to it's previous state.

The CPL statement does the exact same thing as XOR $FF...its faster though.


                 Thomas J. Hruska -- thruska@tir.com
Shining Light Productions -- "Meeting the needs of fellow programmers"
         http://www.geocities.com/SiliconValley/Heights/8504
                    http://shinelight.home.ml.org

• A82: Contrast
• From: Erik Larsson <larsson@alvar.pp.se>
• Re: A82: Contrast
• From: Andrew Von Dollen <warn@mail.geocities.com>

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