The hidden beauty of the Brag Spario and another bug!

Finally finished the transcode of the Andor Genesis (mothership) and its preceding entourage; the Sheonites, the Garu Zakato (big exploding bomb) and Brag Spario (chaser bullets). Oh and the escaping Bragza!

The Andor Genesis descends,
and the sprite-per-scanline limit is just being exceeded

Interesting things happen when you're invincible. Whenever I've played the game, when awaiting the Garu Zakato I've always lurked at the bottom of the screen in order to more easily dodge the bullets. The Brag Spario approach the Solvalou but disappear off the bottom of the screen when you dodge them.

Whilst tesing the transcode, I ventured right up to the top of the screen before the Garu Zakato exploded! Ordinarily, you'd be destroyed by the radiating bullets almost immediately. But being invincible, the Brag Spario started orbiting the Solvalou like a display of orbital mechanics! It looked pretty cool, but I suspected a bug in the transcode. However when I fired up the arcade original and tried the same with invincibility - the same thing happened!

The Brag Spario should have featured more prominently in the game, to show off their fancy flying!

I also found a bug in the game, and again, I verified it on the arcade original! When destroying the Andor Genesis core, you score more than the allotted 4,000 points! See below, where I scored 4,010.

Can't really show the Brag Spario in a screen shot,
so instead a blew up the Andor Genesis core

It all comes down to how the Andor Genesis is represented in the object table. Last post I mentioned it comprises 9 'body' objects, 5 objects for the 4 gun ports and central core, and a 15th 'master' object which initialises the other objects and is used as the reference for the sprite coordinates etc.

Well, the way the bombing code works is that whenever your bomb explodes, it loops through the first 16 objects (ground-based objects) in the object table, destroying any object within range of the explosion. This is how you can destroy multiple objects, such as adjacent Lograms and Zolbaks, on the ground with single bomb.

So when you bomb the core, it first matches the core object (object #14) and you score the allotted 4,000 points. But then it continues and also matches the master object (object #15). However the master object never initialises the POINTS value (incidentally, there is no value that represents 0 points). So you are awarded the point value for the last object to occupy that slot.

For the Andor Genesis in Area 9, the last object was a Zolbak in Area 8, and so you are awarded an additional 200 points. When I was testing in the above screenshot, I was starting in Area 9; no object had been previously assigned to that slot, so POINTS was 0, which represents 10 points. You may recall, this is the same reason the Easter Egg at the start of the game is also worth 10 points.

I guess this means I'm finally up to the flying objects. The handlers for these tend to be a little more complex due to the flight patterns and the AI that affects their behaviour. Should be fun... but I might see if I can finish off the SUB CPU completely first...