Double buffer demo

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Double buffer demo

Post by Indyuk2000 » Mon Sep 26, 2022 8:37 pm

Hi Keith,

It's been a while since I last posted on here. Hope you're doing well. I've still been dipping in/out of CPC Z80 development. Here's something that I've been working on lately and thought I'd post a video (link) for all to see.

I set myself a target of seeing what can be achieved with just using firmware and a bit of careful planning and tweaking. I know there are many advance techniques out there for the CPC but, I was more interested in experiencing what it would have been like to be a CPC developer at the CPC's launch (1984?) when no one knew what could be done with the CRTC

The demo you see is nothing special and doesn't come close to what you did in your Chibi games but, I think it's not too bad when you consider it's rendering every frame;

1x player sprite 8x16
12x alien sprites 8x8
8x stars
anything between 8-10 alien bullets on-screen, each 3x3
anything between 6-8 player bullets on-screen, each 3x3

I'm using double-buffering to get smooth as possible graphics and think it's doing a pretty good job. Player control is just simple left/right and fire and, aliens are just continously dropping from top to bottom and firing as they travel. There's no sound so not sure how much overhead to expect from that but, not worrying about that yet and, besides, if this ends up as a potential game, this would not have so many sprites at once.

Let me know what you think.


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Re: Double buffer demo

Post by akuyou » Thu Sep 29, 2022 11:12 pm

That looks great!

The animation looks really smooth, and there's lots going on on-screen.

Out of interest, are you clearing the buffer and redrawing all objects each frame (how chibiakumas worked) or just what moved since the last buffer (I guess that could be faster)

Anyway, It looks great! it reminds me of the Galactic Plague game from Amsoft, which for some reason it seems everyone hates, but I thought was kinda fun.

Your comments on the firmware are a good point people often forget, I hear a lot of people ask why 'games were so limited' back in the 80s, when they don't seem to recognize that the developers where having to try to adhere to the specification docs to ensure compatibility and future proofing

Good luck with your programming!
Chibi Akuma(s) Comedy-Horror 8-bit Bullet Hell shooter! // 「チビ悪魔」可笑しいゴシックSTG ! // Work in Progress: ChibiAliens

Interested in CPU's :Z80,6502,68000,6809,ARM,8086,RISC-V
Learning: 65816,ARM,8086,6809

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