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null
Account closed
Registered: Jun 2006
Posts: 645 |
HCB - what is it and what can we do with it?
okay, so.. I was (and possibly others are) wondering what HCB is exactly? what are the possibilities and limitations of this new GFX mode? and where can I get an editor for it? :_)
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Frantic
Registered: Mar 2003
Posts: 1648 |
There was an editor on disk 0 of the demo? |
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null
Account closed
Registered: Jun 2006
Posts: 645 |
was there? then I should look again when I get home! :_)
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Shadow
Account closed
Registered: Apr 2002
Posts: 355 |
I'd like to know the technical details behind the format - how does it work? |
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Ksubi
Account closed
Registered: Nov 2007
Posts: 87 |
Having played around quickly with the editor, I think you can have 4 colours per 4x8 block, that is 3 colours plus the background. |
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Oswald
Registered: Apr 2002
Posts: 5094 |
Quote: I'd like to know the technical details behind the format - how does it work?
basically like 4x4 in other words like every 4th line fli. the trick is that the VIC only reads d800 information on badlines, so you have about 3 rasterlines to rewrite $d800 on the fly in the middle of the chars. then I think you would reset $d800 on the border area.
so hcb is basically every 4th line fli - but d800 is included in the new colors. |
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null
Account closed
Registered: Jun 2006
Posts: 645 |
wait, so it still has that shitty FLI bug? lame..
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Shadow
Account closed
Registered: Apr 2002
Posts: 355 |
Thanks Oswald, I think I get it now!
So in essence:
(Badline, $d800-$d827 is fetched by VIC)
Routine start LDA/STA new colors into $d800-$d827
(4 lines later we trigger a new badline, $d800-$d827 is fetched again, but this time we have new values!)
... repeat for next line etc.
If I count correctly the lda/sta for 40 colorram-values should take 240 cycles, which is just about doable in 4 rasterlines, so it all works out nicely.
-edit- and if we have the FLI-bug in effect, we can skip 3 of those, so we only need to update 37 colorram-values.
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WVL
Registered: Mar 2002
Posts: 902 |
dont forget that there are only 16 different colors -> there's no need for 40x lda # ;) so you can do it with 16* lda # ->
40 writes = 160 cycles + 16 lda # = 32 cycles = 192 cycles, almost there ;) and if you dont use the first 3 chars, you're in business!
BTW, now that i think of it, you only need 8* lda #, because if you load values 8-15, you can also write values 0-7 if you use SAX. profit! |
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Cruzer
Registered: Dec 2001
Posts: 1048 |
And no one says all d800 values change for every line, so the # of sta's can probably be < 37 too. Unless you wanna make effects with it, like the fading in EoD. In that case it's probably better to keep all the sta's.
Quote:wait, so it still has that shitty FLI bug? lame.. But there's rtime for 8 sprites that can cover the bug. You could also get rid of the bug, but that would limit the height of the gfx to 4 chars.
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algorithm
Registered: May 2002
Posts: 705 |
As the updating is dynamic, its probably a better idea to change all 40 cells. Its understandable that there will be less than 40 changes in each line but there would be no consistancy. Some char lines may have 12 changes, some 23 etc and having to modify before bad line and then change back to the previous after the bad line etc.
Its possible to feed the image data through some type of 'converter' which can ensure only a maximum of x amount of changes with less color error
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