BTW, sorry for the long lines in that last mail, trying a new mail
client that *told* me it was going to automatically wrap, but didn't...
On Fri, 28 Nov 2003 09:59:38 +0100, Thomas Jentzsch <tjentzsch@xxxxxx>
wrote:
Here's how I did the positioning. First, my code actually displays *15*
columns of invaders, spanning the entire screen.
Correction here: 15*9 - 3 = 132. ;-)
Actually, it's 15*9 + 6 = 141. The 15 columns are always
there and can be shifted by up to 6 pixels. OK, it's not *quite* the
entire screen, but it's closer than Instigators. Looking at the source,
I think my leftmost limit was pixel 20, and then having 15 columns
places the rightmost limit very neatly right at 160.
But IIRC there is a big problem with hitting RESPx every 3 cycles,
because
gaps in the formation cause the preceding (following) invader to be
shifted
by one pixel. And AFAIK nobody has found a solution for that problem yet.
Did you? That would offer some great new options for better code!
No, I never solved that. My solution was just to accept the single-pixel
shifting, because I thought it preferable to have the overall tighter
formation and easy single-pixel positioning. (You disagreed; I think
back when I first posted my demo, you bragged how your beefy invaders
would eat my tiny ones for breakfast. ;) )
This would normally cause HMOVE blanks at the left and then hide my first
two invaders. Therefore I am using early HMOVEs, which don't create those
blanks.
Very clever, of course. I actually wrote my demo some time before we
figured out any of the illegal-HMOVE trickery. This would've been around
summer 1997, IIRC.
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