| |
Digger
Registered: Mar 2005
Posts: 437 |
Doubling char lines with stretched sprites over it
From VIC article it seems impossible but I thought I'd ask anyway:
Is it possible to have first charline duplicated all the way down (standard line doubling trick with badline skipping) with 8 stretched sprites over it?
Seems like sprite 0 data is fetched right where the line doubling should be triggered (cycle 58).
Have spent already too much time trying to (unsuccessfully) cycle this, thus time to reach out. Cheers! |
|
| |
Compyx
Registered: Jan 2005
Posts: 631 |
You can inhibit the sprite 0 DMA fetch by using 6-cycle instructions (DEC $d016) to open the border and do the proper $d011 writes I think.
Though I'd have to look up old demo parts to make sure I actually put an 8-sprite stretcher in the border and not a 7-sprite stretcher. |
| |
HCL
Registered: Feb 2003
Posts: 728 |
You didn't ask for open sideborders, did you?
It is of course possible to double charlines with 8 sprites on top (even stretched using d017), however opening sideborder has not been done with this combination. ..and i have tried :)
I am using it in.. uuuh.. EoD and probably a handful of other demos. |
| |
Digger
Registered: Mar 2005
Posts: 437 |
Thanks HCL :) Than I will keep trying.
Yeah, no sideborders, since it's only possible with 7 sprites and line crunching. |
| |
Krill
Registered: Apr 2002
Posts: 2980 |
Unless NTSC or PAL-N (Drean) :D |
| |
HCL
Registered: Feb 2003
Posts: 728 |
Check the interference circles in Uncensored/BoozeDesign, that's a good (?) example of a sprite-fpp over badline-less bitmap. Timing code at $1100 somewhere.. |
| |
Digger
Registered: Mar 2005
Posts: 437 |
@HCL: I was actually watching it last night, it's interesting how you shift starting Y positions for each sprite to be able to switch all pointers with one value.
I was thinking to use $d018 for that but seems more memory efficient with your approach, no screen RAM/bank switching needed. |
| |
Compyx
Registered: Jan 2005
Posts: 631 |
Quoting HCLYou didn't ask for open sideborders, did you?
It is of course possible to double charlines with 8 sprites on top (even stretched using d017), however opening sideborder has not been done with this combination. ..and i have tried :)
I am using it in.. uuuh.. EoD and probably a handful of other demos.
Oops, I somehow always associate sprite stretching with open borders. :)
That said, I couldn't find any old code of mine using 8 sprites, I sure tried, but never succeeded it seems. |
| |
Dano
Registered: Jul 2004
Posts: 234 |
Quote: Check the interference circles in Uncensored/BoozeDesign, that's a good (?) example of a sprite-fpp over badline-less bitmap. Timing code at $1100 somewhere..
the sprite stretcher in reluge should use about the same technique i guess (without checking it). :) |
