ZAD Adventure System - Progress

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PROSM
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ZAD Adventure System - Progress

Post by PROSM » Wed Jan 17, 2018 11:06 pm

Hello there,

I've been writing a graphical adventure system recently which aims to allow one to create games in the style of the old SCUMM adventure games (e.g. Maniac Mansion). It's called ZAD (ZX Adventure Designer) and can produce games which run on a ZX Spectrum with at least 48K of RAM.

So far, the bytecode interpreter has been fully implemented and debugged, along with both the base-level graphics functions and the redraw manager, the walking mode and the keyboard scanning routines. The items that are still yet to be implemented are the interactivity system (being able to select a verb and then position the cursor on the object to perform the action) and the tape system (reading and writing save-files to cassette). Hopefully, I should be able to get these done by the end of January at the earliest, or possibly mid-February.

All background images used in the game are compressed via Einar's wonderful ZX7 tool, without which this project wouldn't have been remotely feasible.

Below is a video, showing a test game which demonstrates the abilities of the engine at this point. I must mention that, while there are full message line capabilities in this build, they are not used in this demo.

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Currently working on ZX Adventure Designer, which lets one create point-and-click graphic adventures for a 48K Spectrum.

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R-Tape
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Re: ZAD Adventure System - Progress

Post by R-Tape » Wed Jan 17, 2018 11:15 pm

This looks fantastic.

I'm not clear - is this a utility that runs on a spectrum or a PC?
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Re: ZAD Adventure System - Progress

Post by PROSM » Thu Jan 18, 2018 6:50 am

R-Tape wrote:
Wed Jan 17, 2018 11:15 pm
This looks fantastic.

I'm not clear - is this a utility that runs on a spectrum or a PC?
The development kit is a set of utilities that runs on Windows (they could of course be ported to other OSes). In reality, there are only two utilities, both of which handle graphics conversion. All of the bytecode compilation is handled via a set of PASMO macros.
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Currently working on ZX Adventure Designer, which lets one create point-and-click graphic adventures for a 48K Spectrum.

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Re: ZAD Adventure System - Progress

Post by Morkin » Thu Jan 18, 2018 8:05 am

Looks cool..!

I like the main sprite's blinking animation.
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Re: ZAD Adventure System - Progress

Post by RMartins » Thu Jan 18, 2018 10:27 am

Nice work, keep us posted on the developments.
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Re: ZAD Adventure System - Progress

Post by Ralf » Thu Jan 18, 2018 10:39 am

Very interesting project! It would be great if you made it to the stage where creating actual games would be possible.

Remember that if you want other people to use it it must be friendly, bug free (mostly ;) ) and well documented. In the past
many people tried to make some engines that turned out unusable in the end.

Also the engine can't take too much memory. If it uses 30 of 40 available kilobytes of Spectrum 48 memory then it would be hard to make any more serious game with it.

How do you store backgrounds? As single, big, compressed pictures or are they built from tiles?

In the video it seems that you have sprite movement by 8 pixels(movement by character)? Are you going to stick to it or more presise movement by 1 or 2 pixels will be available too?

Generally as I said it's very interesting news. Don't forget to write some progress reports here! :)
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Re: ZAD Adventure System - Progress

Post by 4thRock » Thu Jan 18, 2018 4:11 pm

A Windows program is great! :D
Spectrum based game creators are harder to use...

Looking forward to it!
I like the full color, 8x8 animation. Multicolour to sprites would be a nice addition.
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Re: ZAD Adventure System - Progress

Post by PROSM » Thu Jan 18, 2018 7:14 pm

Ralf wrote:
Thu Jan 18, 2018 10:39 am
Very interesting project! It would be great if you made it to the stage where creating actual games would be possible.

Remember that if you want other people to use it it must be friendly, bug free (mostly ;) ) and well documented. In the past
many people tried to make some engines that turned out unusable in the end.

Also the engine can't take too much memory. If it uses 30 of 40 available kilobytes of Spectrum 48 memory then it would be hard to make any more serious game with it.

How do you store backgrounds? As single, big, compressed pictures or are they built from tiles?

In the video it seems that you have sprite movement by 8 pixels(movement by character)? Are you going to stick to it or more presise movement by 1 or 2 pixels will be available too?

Generally as I said it's very interesting news. Don't forget to write some progress reports here! :)
Thank you for your kind words, Ralf. I certainly aim to get this engine to a usable state, as I intend to write a game or two myself with it. The graphics you see in the video are rough drafts of those to be used in my game. As for the manual, I have all of the technical documentation written, but before I release the engine to the public, I will also have to write a tutorial to help people become familiar with the engine. In addition to this, while PASMO is fairly good at compiling the bytecode via macros, I imagine that others would want a dedicated compiler to make things easier.

Memory isn't a big concern, and is extremely unlikely to ever be one. Although it's not definite right now, an estimated 30KB will be available for game data. According to my estimates, a typical in-game room will take some 400 to 800 bytes, so you'll be able to have an average of around 30 rooms, taking into account the extra memory eaten up by frames (the graphics for the movable objects). Of course, this varies depending on how much data each room uses.

The backgrounds are stored as tile maps which are compressed via ZX7. In fact, the way in which graphics are drawn to the screen is pretty much via an emulated character mode. This unfortunately prohibits me from making the movements of objects more precise than 8 pixels, and it also introduces a considerable overhead in drawing the graphics to the screen, but this is outweighed by the fact that it greatly reduces the amount of memory needed for the graphics data and screen buffers, since only 2 bytes (tile index and attribute) are needed for each character block. The off-screen buffer takes only 1KB of memory and the universal character set needs only 2KB to store all 256 characters.
4thRock wrote:
Thu Jan 18, 2018 4:11 pm
A Windows program is great! :D
Spectrum based game creators are harder to use...

Looking forward to it!
I like the full color, 8x8 animation. Multicolour to sprites would be a nice addition.
I agree that Spectrum-based creators are harder to work with. Really, in my case, it needs to be a set of Windows utilities due to the sheer amount of data to manipulate for such a game. In addition, ZX7 is needed for the compression of the graphics, so part of the development environment would have to run on a modern computer anyways.

I'm glad you like the full colour animation in my game, but unfortunately, multicolour would not be possible due to the amount of CPU time that it requires and also the amount of memory that storing such data would require (5 bytes per character for an 8x2 attribute layout).
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Currently working on ZX Adventure Designer, which lets one create point-and-click graphic adventures for a 48K Spectrum.

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Re: ZAD Adventure System - Progress

Post by Ralf » Thu Jan 18, 2018 8:10 pm

Thanks for the explanations.

I suppose 8 pixel movement would force some "style" for the games. As sprite will move by 8 pixels, they can be colourful without too much colour clashing, just like in your example. And I suppose they can be BIG :) With 8 pixel movement big sprites move bettter, you don't feel that the movement is jerky.

So if I were to make some game with it, personally I would go after something similar graphically to Trap Door, Flunky, Benny Hill and other games by Don Priestley.

Anyway good luck with your project!
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Re: ZAD Adventure System - Progress

Post by R-Tape » Thu Jan 18, 2018 10:50 pm

Does this cyan blob have a name by the way? Tell me it's not Horace!
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