Author Topic: My Absurd Demos from the 90s  (Read 259 times)

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Offline AMSDOS

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My Absurd Demos from the 90s
« on: 08:14, 27 October 18 »
Back in the 90s I was putting together game discs and writing my own little Menus to select the game, though along with that Menu I also had a little demo. Sometime ago I transferred some of those from disc to disk image and came across a couple a few weeks ago and decided to update them :D



They aren't going to set the world on fire in terms of tricks there's no Rasters or Overscan or Split Modes, I did make one little Demo back then which used a program from AA17 Type-ins to split the Colours midway across the screen, though haven't included it here.





Police Car Demo

The original program is called CAR.BAS, which is a BASIC stub file (a file with BASIC followed by MC routines), back when I made it, I was using the Spriting Back Utility which was on the AA106 Covertape, which had it's own Sprite Designer. The idea with it was to draw a rectangle around the sprite and set it to 0 or whatever the background colour was, so it would wipe the Sprite as it moved. Apart from that the routine has it's own guide to how to set coordinates across the screen, I must of known how it work back then because it's quite different to Sean McManus' ESD Advance for example. The other feature of this demo is the Screen I made back then, I probably made it with the early GPaint from the AA80 covertape and then I used the early version of Colombia to compress the screen, which is what you can see in operation onscreen when CAR.BAS is initially RUNning.





Updated BASIC Version

It's still using the Spriting Back Utility from the AA Covertape, though I decided to use BASIC to draw the screen, the hardest part is the nature strip, I had to come up with a simple way of checking both sides of the curve and use MOVE and DRAW to fill those two points in, thus creating a simple FILL routine, I wasn't sure how good it would be, so I straightened out the angled edges, which left me with a bit of line to draw at the end, though generally speaking the general idea is there even if the median strip is slightly different. For the red dots to be placed in the centre of the Grassy area, it was simply a matter of working out Random Values between the 2 Points again, though use some conditioning when the Median Strip changed so it would remain within. Overall, I was happy with the result. The resulting program is called PATROL.BAS


Coding in Hisoft Pascal

From the BASIC version, I was able to come up with a Pascal equivalent, though I've been using Sean McManus' Easi-Sprite Driver Advanced, so I had to convert the sprite so it had dimensions and also changed the sprite to XOR, which means a Border isn't necessary. Since it's only a single Sprite, I also used Hisoft Pascal to build the Graphic up in sets, so the whole program handles everything from within. The most noticeable change between this and the BASIC version is obviously going to be the FILL routine, from the compiled environment it looks similar to the BASIC 1.1 FILL. The resulting Compiled Program being in PATROL.BIN


Police Cars aren't White!

Well maybe not now, but back in the 90s they were, well I suppose some still are here in Australia, a Highway Patrol car perhaps isn't, this looks more like your little Suburban Car doing it's rounds!  :D 







The Cliff Man!

I never really had a title for this, it's simply a little Viking Character I drew up myself charging from one side of the screen to the other, with a Cliff in it's Path. Back when I wrote it I had no concept of Array's so no check routine to check when he should drop, I haven't complicated things by adding one either and have just stuck to the old true method of Drawing this character so far before having them drop, this demo really shows how well my Animation sequencing works and even now it's a simple 2 sprite approach. Like my 1st Demo, this also used the Spriting Back Utility and with again Invisible Box placed around.




I updated again using ESD Advanced with Hisoft Pascal just to see how well the Animation with a Background in play would perform, was also an opportunity to use the simple mask pattern generator to draw a background, however while I was in the process of using it, I found a bug which relates to when the position changes (from the left side of the screen it works perfectly fine, but offsetting the x-coordinate and problems begin to emerge, the solution which I hadn't done in my BASIC example was to add X to the Final value from within the FOR loop, thus correcting that), in this demo the pattern shifts when the 1st lot of ground on the left side is found and needs to follow down to the displaced ground that the Viking Falls down to. Overall again I'm happy with the result.  :D




« Last Edit: 08:19, 27 October 18 by AMSDOS »
* Using some of the hardly used Amstrad compilers :D
* I use Firmware in my Assembly code :P
* Have interpreted some BASIC 1.1 programs for BASIC 1.0. :)

Offline AMSDOS

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Re: My Absurd Demos from the 90s
« Reply #1 on: 12:08, 27 October 18 »
Had a bit of a read up on the Spriting Back Utility from the AA106 Covertape Page, it appears Simon Forrester was going to write a followup article about it, though it appears it never eventuated. It's been setup though for someone new to Sprites and looking to add Sprites into a simple program. The Coordinate system is setup to be quite broad though, it's not a true Text Coordinate system, although in a sense it's setup as a grid 80 squares across (equivalent to MODE 2), 50 squares down, which would make that every 8 pixel lines, which when running in conjunction with my earlier Demos is the reason why the Sprites Move quickly across the screen.
* Using some of the hardly used Amstrad compilers :D
* I use Firmware in my Assembly code :P
* Have interpreted some BASIC 1.1 programs for BASIC 1.0. :)

Online Gryzor

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Re: My Absurd Demos from the 90s
« Reply #2 on: 16:34, 01 November 18 »
Thanks for sharing :)