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Heat Demo


Heat demo
Introduction screen to the "Heat demo".

Burning match
The burning match on the CPC Plus
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.

Odiesoft logo
The Odiesoft logo is burning (regular CPC)
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.

Burning match
The burning match 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!


Fading Odiesoft
Fading Odiesoft logo (on regular CPC)
Fading Odiesoft
Compare: Fading Odiesoft logo on a CPC Plus


Lighted match
Lighted match (on regular CPC)
Lighted match
Compare: Lighted match on a CPC Plus


Moving match
Match moving around (on regular CPC)
Moving match
Match moving around on a CPC Plus


Moving match
Match moving around (on green screen)
Burning screen
Burning inferno on a regular CPC


Match and fire
Match and fire with sparks (on CPC Plus)
CPC Comparison
Compare (from left to right):
CPC Plus, Green Screen, regular CPC


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last updated on Sunday, December 22. 2002 by Odiesoft

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