Path: chuka.playstation.co.uk!news
From: "Alex Herbert" <alex@herbs.dabsol.co.uk>
Newsgroups: scee.yaroze.freetalk.english
Subject: Re: Have I mentioned this before... bgWorkArea?
Date: Sat, 7 Jul 2001 23:18:34 +0100
Organization: PlayStation Net Yaroze (SCEE)
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Were we reading eachother's minds?

Alex

"John ( QuietBloke )" <quietbloke@btinternet.com> wrote in message
news:9i810e$dor6@www.netyaroze-europe.com...
> Im not quite sure what your after Max..
>
> The bg Work area is an area of memory you allocate which the Libraries
need
> to use when displaying the tiled background.
> The formulae doesnt relate to number of pixels on the screen just like the
> size of a GsSPRITE doesnt relate to the number of pixels.
> Its merely how much space is required by the libraries to process and
> display your tileset.
>
> Also I cant see how the formulae can return a float.
>
> What your really after is an explanation of exactly what the libraries do
in
> order to display a tileset and therefore why they need to use exactly that
> amount of space to do thier thing.
>
> Id be very interested to fnd out the exact details myslef but looking at
the
> formulae you could make a fairly reasonable stab at some of it:
>
>
> My Rough guess work says the formulae is :
>
> (ScreenW/CellW+1)  = maximum number of tiles which can appear on screen in
> the x direction
>
> (ScreenH/CellH+1+1) = maximum number of tiles which can appear on screen
in
> the y direction + 1. I still have no idea why you need to add another one
> here.
>
> Multipy the two together to gives total number of tiles we need to be
store
> information about.
>
> Multipy the result by 6 = For each tile the Library functions need this
much
> work space to do its thing. I Guess this would be stuff like GsCell info +
> phsical screen position.
>
> Then add an additional 4  u_longs = I guess these are required to store
> additional information about the whole displayable tileset ( at a guess
this
> might be to hold something like the x/y offset within the top/left tile
> corresponding to pixel 0,0)
>
> Muliply the result by 2 = <shrug> A long shot but maybe just like the
> gpu_buffer we require 2 buffers.
>
> Finally add another 2 u_longs = Dunno.. Guess the tileset needs some more
> global information. Perhaps an offset where the second buffer exists
within
> the workspace and which buffer we are currently working on ?
>
>
> Then again I could be way off and totally wrong.. In which case can
someone
> give the real reason for the formulae ? It would be intersting to know how
> the formulae came to be.
>
> Cheers
> John ( QuietBloke )
> With more insane ramblings
>
>
> "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
> > > >
> > > >
> > >
> > >
> >
> >
>
>