Path: chuka.playstation.co.uk!news
From: "Max" <mad.max@which.net>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: Have I mentioned this before... bgWorkArea?
Date: Sun, 8 Jul 2001 16:44:44 +0100
Organization: PlayStation Net Yaroze (SCEE)
Lines: 122
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Yeah, the floating point thing was crap.. guess I should check my facts
before I babble cack :) I just remember one time I managed to get a float
from it - just an error in calculation I guess.

For now I have left out any complex explanations and just left it kind of
open in my explanation of it in the tutorial. I have uploaded it to my
yaroze web space for download if anyone is interested. Have a look and see
if you can find anything wrong with it... the new stuff is the BG stuff. It
comes in .zip and .rar flavours at http://www.netyaroze-europe.com/~leon17

Pretty much everthing that was said could make sense - the caching is a good
one makes sense when you think about it - but thanks guys.

I wonder if George Bain knows???

Max

Alex Herbert <alex@herbs.dabsol.co.uk> wrote in message
news:9i81j1$dor7@www.netyaroze-europe.com...
> Hi Max,
>
> I tried to work this out before and some of it makes sense...  sort of...
>
> If the bg is scrolled to the left a few pixels, an extra tile becomes
> visible on the right hand side of the screen making a total of 21 titles
> across, hence the first +1 in the formula. The same applies to the y-axis
> which explains the second +1.
>
> I'm not sure about the third +1, but it seems to suggest an extra word is
> needed per row of tiles.  Can't imagine why - flags maybe?  I first
thought
> this might be a typo and left it out without any obvious problems, until I
> tried a high-res interlaced mode and the bottom 2 rows of tiles were
getting
> messed up.  I put the +1 back in and it all worked fine.
>
> I'm guessing that the GPU primitive for a 16x16 tile is 6 words in length
> and hence the *6.  I'm not sure about the +4.  Flags again, maybe?
>
> I think the *2 is needed for double buffering.  The bgWorkArea will need
to
> hold 2 packet workspaces as normal - the one being drawn and the one being
> prepared.  Not sure about the last +2.
>
> Oh, and the library reference says the unit is 'long', so no idea why
floats
> would come into it.
>
> Alex
>
>
> "Max" <mad.max@which.net> wrote in message
> news:9i7ktj$dor5@www.netyaroze-europe.com...
> > Hmm..
> >
> > Its really the +1s and +1+1s and *6+4 etc that I don't understand
besides
> > this usually turns up a float value which is wierd considering the
Yaroze
> is
> > a 32 bit integer machine and the value you get from this formula is
always
> > FAR bigger that you actually need.
> >
> > I don't think I'll ever figure this out :(
> >
> > Max
> >
> > Alex Herbert <alex@herbs.dabsol.co.uk> wrote in message
> > news:9i4sa2$b933@www.netyaroze-europe.com...
> > > Hi Max,
> > >
> > > According to the Library Reference (page 142):
> > >
> > > size=(((ScreenW/CellW+1)*(ScreenH/CellH+1+1)*6+4)*2+2)
> > >
> > > Hope this helps.
> > >
> > > Alex
> > >
> > >
> > >
> > > "Max" <mad.max@which.net> wrote in message
> > > news:9i4n4l$b931@www.netyaroze-europe.com...
> > > > Hey all,
> > > >
> > > > I've started up again on the 2D tutorial and I'm puzzling over this
> > > > bgWorkArea size. Basically I have played around with it quite a bit.
I
> > > have
> > > > 320 [16x16] tiles on the screen (20 tiles width x 16 tiles height)
and
> > my
> > > > bgWorkArea is (20*16)*12 = 3840, now I get the 20*16 bit - the
number
> of
> > > > tiles on the screen but 12 is just an arbitiary number I put in but
it
> > > won't
> > > > work with anything less. I have also tried SCREEN_WIDTH (320) *
> > > > SCREEN_HEIGHT (256) = 81920 (the number of pixels on the screen) but
> > this
> > > > number far outweighs what I actually need as a bare minimum...
because
> > it
> > > > works with 3840.
> > > >
> > > > Can anyone tell me what the bgWorkArea size is actually mean to
be? -
> > > > please?
> > > >
> > > > Max
> > > >
> > > >
> > >
> > >
> >
> >
>
>