SpiceWare's Blog

I had a large spaceship move from the right to the left and hideout in the wrap zone at the top for about half a screen width!

I did not like that.

Hmm, looking at the code this could have happened before, though making everything use a 16 scan-line wrap zone increased the odds as the saucers used to use an 8 scan-line wrap zone.

 

There's only 10 bytes free in the ARM space. Having everything use 16 simplified a lot of logic, which shrank the ROM requirements for that code, so I'm not able to make the saucer use 8 again. I've not encountered this yet in my tests, so I'd like to see how frequently it occurs. If it's a rare occurrence then it probably won't get fixed.

I took a look at the saucer code and found where I can add some extra logic to keep it from hanging out off-screen in the wrap-zone. It would tie into the logic that keeps the saucer explosion moving in a straight line without random direction changes. I can easily modify that routine to also check the saucer's Y position to see if it entered the wrap-zone. If the saucer stops making direction changes upon entering the wrap-zone, then it will just proceed along it's current heading until it reappears on the other side of the screen.

 

A "bandaid fix" will take 12 bytes, a proper fix will take 20. Either way, that's more space than I have. If the saucer hides out again, for anybody, in the next few weeks then let me know and I'll see what I can do.