Converting a Speccy MPAGD game to MSX

[Minilop]

One of the things that really appeals to me about MPAGD is the ability to port games from one platform to another.  Having released a Speccy game I've looked at converting to Amstrad, but that's going to need a lot of graphical reworking, so I thought I'd have a look at MSX next.  Having 'found' the required ROMs for OpenMSX and getting that installed I set about the conversion process. Using the graphics conversion tools in MPAGD I converted from Spectrum to Timex then from Timex to MSX - the results we're near identical match to the Speccy version - which considering I was using every available block, had about 40 objects and quite a lot of sprites, came as quite some relief.

A few things I've noticed so far:

• having the ability for multicolour objects is really nice, once I'd got my head around how colours work on the MSX its pretty straightforward,.
• sprites however are still monochrome only, which is a bit of a shame since one of the benefits of MSX would be working with background blocks - this means your sprite is one colour & transparent so the background shows through the sprite.
• performance of the game seems a little slower than the Speccy
• memory constraints have meant losing quite a few objects, sprites and/or frames and will mean I have to rewrite/condense the messages file in order to fit in.  I've so far avoided having to delete any screens
• Collision detection seems a little different.

To be honest I know nothing about MSX, and looked at this just out of curiosity, but as it is all working in the main I think I might try and do a full conversion as a side project, my primary focus will always be Speccy first and I have another Speccy game I am working on at the moment,

Anyone else had a go at an MSX game or conversion?

[roolandoo]

Hi Minilop , I saw that you managed to port your game Cocoa to MSX. I'm doing the same with mine: "La Reliquia": roolandoo.itch.io/lareliquia

I already have it operational, but I don't know how to add ingame music. For the Spectrum version I used MPAGDMusicizer but obviously it doesn't work with MSX.

You can help me?

[ultranarwhal]

Adding music to MSX is much easier, basically the music needs to be in the Suite MSX/Resources folder. If you look at README.md in the Suite MSX it explains what to do.

[roolandoo]

ohh, thank you very much ultranarwhal , it works fine. The problem is that I can't fit the songs due to lack of memory in MSX1 and I would have to delete something. Is it not possible to generate a version for MSX2? I say this because it would have more memory.

[Minilop]

Unfortunately the MSX Engine only supports MSX1 at the moment, I had a similar problem when migrating Cocoa to MSX, I had to reduce the game size in order to fit it into the available memory for MSX 1. To do this I had to reduce the number of sprites and blocks and do as much code optimisation as possible, If your game has a lot of text in it then see if you can reduce that, that's another space-saver. Hopefully one day the guy who developed the MSX engine will enable it to support MSX2 - at which point I think I would be able to do the MSX conversion it deserves. However, based on download numbers for the game, the speccy version is way more popular. (By a factor of 20!)

[ultranarwhal]

Don't think MSX2 version would help with the size constraint. It appears AGD is limited to maximum 48K (even for Speccy), as I tried compiling a game using more than 48K and it wouldn't compile.

There are improvements coming to the MSX engine that could free up a little more memory, but maybe not enough if you use lots of music.

Basically go through game and thin down text, frames, spriteink, paper/ink (use colour),block variance.

[roolandoo]

Ohh, sorry to hear that. My game is already refined to the maximum and I cannot cut anything without losing the essence. The Spectrum version is 48Kb. but the Musicizer allows to inject music by taking advantage of the 128Kb memory. There must be a way to do this on MSX.