Tuesday, March 25, 2014


What a difference a mere week can make in terms of progress. At the beginning of last week only the basic background from one scene was showing, although there was more code implemented in the engine that wasn't yet working. Now, a week later, behold the progress of Rex Nebular on ScummVM:

That's right, in a rush of effort this week, the Rex Nebular engine has already passed several milestones in development:
  • The user interface is now partly implemented. As you can see from the above picture, the user interface background is showing, with the sections for the actions, items, and the animated inventory item showing.
  • The scene background is now displaying, along with basic sprite animations within the scene. The fires are burning, and the hamster "auxiliary power" :) is running.
  • Basic player display. Rex is in his default position for the scene, facing the door.
  • Behind the scenes, we've already completed the logic for a couple of the game scenes, although we're obviously not able to test them properly yet.
The focus for the upcoming week will now be on the beginnings of user interaction and action handling. This means getting walking working, selections in the user interface, and actually being able to execute actions. A lot of the needed code is already in place, but will require some heavy duty debugging and comparison against the original to figure out where things are going wrong. We're somewhat hampered by the complexity of the core engine when doing debugging, but we'll get there eventually. :)

Friday, March 14, 2014

Rexing it Up

Work has been progressing furiously with the MADS engine, and Rex Nebular support. Whilst I was able to us some code from the previously engine version, a lot of it turned out to be more M4 specific than I'd anticipated, and had to be freshly disassembled and/or rewritten. Additionally, with my greater experience writing engines, I've been able to lay out a cleaner separation of methods into classes than previously, particularly keeping in mind extensibility for having separate game logic for the other MADS games. As a result, the new MADS engine is already significantly different from the old M4 engine.

After a great deal of implementation, not to mention debugging of my code and comparison against the original running in DOSBox, I finally have the background of my test scene showing! See below for the first 'new engine' view of Rex Nebular in all it's glory:

Particularly auspicious considering I see that Rex Nebular has just been released for sale on GOG. So presuming that the engine gets finished this time, people will easily be able to obtain a copy. :)

What's next? In order to reach my original milestone of having an animation sequence playing correctly, it meant that I needed to properly implement the entire frame step and rendering logic from the game, which had a great deal of code, and many different secondary methods that I've encapsulated into a multitude of classes for sprite sets, pending sprites, active sequences, text display, and lots of other things. Not to mention a pretty complicated precursor to M4's RGBList, where resources loaded in for both the scene and for sprites are allocated chunks of the palette space.

I'm currently focusing on debugging the standard sprite drawing, which is used by the animation class. I'm hoping with a bit more work, I can it to properly show the animation sequence. Doing so will also help ensure that all the sprite display logic for the scene also works correctly. This will make it easier to start work later on for full blown game scenes, since all the necessary sprite display will already be done, and I can concentrate on things like player movement, action handling, etc.