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*                                                                             *
*   Demo:   Heat Demo          Type:    Amstrad CPC Emulator DSK File         *
*   Author: Odiesoft           Webpage: http://www.odiesoft.de                *
*   Size:   1 * 194816 Bytes   Date:    24. February 2004                     *
*   File:   Odiesoft Demos - Heat Demo (1996).DSK                             *
*                                                                             *
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Title: Heat Demo
Year:  1996


I've created the first fire effects on my Acorn Risc PC back in 1995. After
finishing Megablasters on the CPC I turned a little more to the Risc PC I've
bought in 1993 from Leather Rebel, hoping to master this machine in order to
create games and demos on this computer as well. At one time I was even planning
to release a Risc PC version of Megablasters, but I never started it.

During my first steps on the Risc PC I've also created a fire effect, which was
very popular among the demo coders of that time. Even though this effect is
calculation intensive I wanted to try to convert it to the CPC. Of course the
first version was pretty slow and I've worked a lot on the program in order to
get more speed out of it.

The final version was still slow, but considerably faster than the first version
I had created. The fire effect runs in a 64 bytes by 160 lines screen size which
enables the programmer to use 8 bit display routines only (instead of 16 bit,
which takes more time). Each point is being calculated by an interpolation using
the four next neighbours, which were added up, subtracted by a number specifying
the decay of the fire over time and then divided by four (through two right
rotations of the register). So the CPC has to do 40960 additions, 10240
subtractions and 20480 right rotations for each frame.

It's no wonder that the small CPC with just 3.75 Mhz speed is overcharged with
all this.

I've created special green screen and CPC plus versions of the demo. The CPC
doesn't have this many hues of the color red available, so the demo doesn't look
this good on a regular CPC. At one point I even considered using blue fire
instead of red since there are more blue hues available than red, but it would
have looked dumb I guess.

The green screen version makes use of the fact that the 26 colors on the CPC are
lined up according to their hue on a green screen. So color 1 (Blue) is the
darkest color on a green screen and color 26 (white) the brightest. It was easy
to fix the program to make use of these colors. And the program looks pretty
good on a green screen.

For the CPC plus version I've added not only more colors since I was able to
choose 16 out of 4096 colors, but I've also included hardware sprites for the
match that floats around the screen and later for the sparks that are emitted by
the fire.

This demo was meant to be part of a megademo. I've made it in advance, so
whenever somebody asked me whether I wanted to participate in another megademo
(like I did in Divine, Shinings XMas Party Demo, the Castle Party Demo, Jubilee
Joy and the Syscrash Megademo) I already had a finished demo part at hand.

But nobody ever asked me again and so this demo was left unreleased on a disc in
the cupboard. I finally passed it around on the CPC Reunion in 2001. I told
everybody that this was an old demo and that I won't have the time to come back
to the CPC, but somehow the rumour surfaced anyway that I was working on the CPC
again.

So here's it for everybody to write down and remember: I won't come back to the
CPC! Sorry, but I just don't have the time for that anymore!

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*                                                                             *
* This program can be distributed freely and without the need of a written    *
* of a written permission by Odiesoft, as long as it is distributed free of   *
* charge!                                                                     *
*                                                                             *
* If you had to pay for this, you've been ripped off!                         *
*                                                                             *
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