It is not realistically possible to show a horizontally-mobile multiplexed-shape sprite on the same scan line as an asymmetric playfield. The only realistic options I can see would be to either use venetian blinds for the whip attack and playfield or use 30Hz flicker between the whip and the player (possibly using a 2x- or 4x-sized whip). The former option might work nicely if the whip attack was only done while facing right (one would switch off NUSIZ0 on the lines with the drawn playfield), but I can't see any way to make it work while facing left, other than Venetian-striping the player (which would probably look bad).
If you do away with the nice looking 'crack' at the end of the whip, you could display the whip as an 8-pixel-wide missile or Ball shifted left or right 7 pixels each scan line. Note that you wouldn't have to write HMxx during the kernel, nor use any logic to decide when to hit HMOVE. Simply hit HMOVE every scan line, and figure the correct initial position for the missile so that it will be in the right place on the lines where it's displayed.
I am thanking you for your input here. I decided to take your advice and do a 30Hz flicker and still keep the 'crack' at the end of the whip. The missle at full 8 times wide fills the void perfectly. THis also allows the whip to be blue like in the original game (or close) And with the player and mace flickering, fully extending is easy enough by also switching out locations for the missle by 8 pixels so that it appears twice its width for the longest primary weapon possible. This will be far easier spreading it out over 2 frames with less TIA register writes for any given scanline.
Big thanks again. This is the first thing to expect in demo form.
Incendently, this will also make going left easier too. I may have the far left (first visible 4 color clocks) not show any sprites as well as the fat right (last 4 color clocks) THis will help to save room and add all the detailsfor read and writes.
Edited by grafixbmp, Fri Nov 7, 2008 6:14 PM.