Sierra AGI Interpreter Update November 2024

Talk about your programs in progress. Discuss how to implement features, etc.
Forum rules
This section is for testing Commander X16 programs and programs related to the CX16 for other platforms (compilers, data conversion tools, etc.)

Feel free to post works in progress, test builds, prototypes, and tech demos.

Finished works go in the Downloads category. Don't forget to add a hashtag (#) and the version number your program was meant to run on. (ie: #R41).
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Manannan
Posts: 69
Joined: Fri Oct 14, 2022 7:23 am

Sierra AGI Interpreter Update November 2024

Post by Manannan »

This post is to provide an update on the Sierra AGI Interpreter I’ve been working on, which I’ve previously shared.

The focus over the last three months has been on achieving a 3D effect. If you’re unfamiliar with these games, they were marketed as “3D” back in the day, though they are what we would now call pseudo-3D. In simple terms, this means that the character can move in front of or behind background objects based on the sprite’s y-position. Later Sierra games using the SCI engine included perspective, but this feature was never supported in AGI games.

For those interested in the technical aspects, here’s a link: http://agiwiki.sierrahelp.com/index.php ... ty_Screens

I’ve also prepared an animated GIF that illustrates this concept better than words. (Note the dithering effect is just an artifact of the animated gif tool)
3dDemo.GIF
3dDemo.GIF (5.53 MiB) Viewed 302 times
Currently, I am handling this 3D effect in the IRQ handler. This works in most cases, but there are occasional IRQ overruns with large split sprites, such as the credits in certain introduction sequences.

My major goals for the next three months are:

- To implement a 3D effect backbuffer to reduce the risk of IRQ overruns.
- To add sprite garbage collection to free up VRAM for the buffer. The introductions contain many large, short-lived sprites (e.g., credits in the King’s Quest III intro), so garbage collection could effectively reclaim VRAM.
- To implement a "wander" feature, so that the chickens in King’s Quest III will roam around their cage without leaving, and the crocodiles in the moats will move around naturally.
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desertfish
Posts: 1094
Joined: Tue Aug 25, 2020 8:27 pm
Location: Netherlands

Re: Sierra AGI Interpreter Update November 2024

Post by desertfish »

woah, is that gif from running on the x16? This has come a long way already! Amazing job
Manannan
Posts: 69
Joined: Fri Oct 14, 2022 7:23 am

Re: Sierra AGI Interpreter Update November 2024

Post by Manannan »

desertfish wrote: Sun Nov 03, 2024 12:14 pm woah, is that gif from running on the x16? This has come a long way already! Amazing job
Yes, this is running on the Commander x16!
voidstar
Posts: 490
Joined: Thu Apr 15, 2021 8:05 am

Re: Sierra AGI Interpreter Update November 2024

Post by voidstar »

We had fun demo'ing KQ1 on the X16 in VCF earlier this year!!

Though - sound support? It was something the CoCo systems never tackled. The early Sierra games had subtle background audio effects, like birds. Then the ultimate was that organ in KQ4.
cosmicr
Posts: 34
Joined: Tue Nov 14, 2023 4:29 am

Re: Sierra AGI Interpreter Update November 2024

Post by cosmicr »

The engine is looking close to finished! Well done on the job! Are the views sprites or drawn to the bitmap layer? In my version I was using sprites which presents it's own challenges but I always assumed they'd be faster than a heap of pixel gets/sets.

I had sound working in my unfinished implementation of the AGI interpreter: https://github.com/cosmicr/astral_body/ ... in/sound.c

Feel free to steal it and butcher it how you like.
We had fun demo'ing KQ1 on the X16 in VCF earlier this year!!
You should have asked me for my Another World port - you could have demoed it too!
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