XeO3: Don't bug me now....

Spent a little time fixing a couple of minor bugs.

The first happens when sprites cross stars - they disapear as though the sprites wheren't masked at all. Odd, because I spent some time making sure the stars would show correctly behind the sprites. I remember this because of the optimisation I did to the sprites where if the character its about to overdraw is $00, it doesn't "mask" it in, it copies it. This was quite a saving and it does 9 of these checks per sprite. Now since the stars are basically characters, I made a choice and accepted the slow down invloved. It would have been quicker for have the stars vanish. Anyway, after shuffling code around trying to figure out what the hell was going on, I discovered that it was indeed a simple bug. The stars were being drawn to the wrong screen. They got drawn to the front buffer, and not the back one. The reason it didn't look terrible is because the stars check to see that theres nothing there before they draw themselves - this is simply so that they'll draw behind the scrolling back ground. Anyway, I changed it to the backbuffer and PING! all is well.

The second was obviously a simple one. once you shot a baddie, he sometimes drops a coin. If you pick up this coin, you get money. However, if you then shoot the space where the coind was, the bullet hit something. Obviously, the coin wasn't as dead as I thought. Turns out when adding the NOSHOOT flag, I'd tried to optimise the bullet collision, and it hadn't worked. It could have, if I'd set that flag on every dead baddie - but I dont want to, so the extra check for it actually being active has to go back in.

Oh well... couple of minor fixes today only... Still, its good to get these things found before any games players find them and complain!

Oh, and with Russell deciding to do a spectrum version, Retro Edit has become even more important...*sigh*... so much for my idea of a simple tool to do the job. This means I'll have to do hires editing, and a spectrum tile editor. Russell has a lot of restrictions for his tiles, so a custom editor is needed. At least the sprite editor will be simpler, but it does mean I've to do it properly and do MCM with bit patterns rather than just numbers - bah!