Blitz (117/144)

From:David McMinn
Date:27 May 2001 at 16:23:26
Subject:Re: 256 Colour screens?

Hi Jason

> Can anyone tell me if it's possible to create a 256 colour, 8 bit plane
> intuition screen. I know that it can be done with a bitmap for use with Blitz
> mode but I cannot find anything about doing the same for screens. In the
> manual it say that the depth of a screen can only be 1-6 bit planes but surely
> you can use AGA's 8. Please let me know if I'm missing something here.

Yes, you can. Tha manual (at least the one I remember reading) did not
get updated when the screen commands where updated, the information for
it was in BUM3 or whatever it was released with. Not sure about the
version of the manual that came with the CD.

I think you need to use the long version of the screen command though:

Screen
screennum,x,y,width,height,depth,viewmode,title$,dpen,bpen[,bitmapnum]

> At the moment whatever I blit get's display scrolled to, so can anyone tell me
> if this solution might work as I really need to use blits and not sprites,
>
> 1. Display scroll the empty background.
> 2. Copy this to a hidden bitmap, out of sight of the main display.

Nope, the displayscroll is a hardware thing that is done to the display
as it gets put out to the display - it doesn't affect the actual in-
memory bitmaps.

> So to escape the display scrolling of the blitted shapes we only display
> scroll every other frame and blit on the frames inbetween thus the display is
> not being display scrolled when the shapes are visible. Any chance of this
> idea working or am I dreaming? If not has anyone got an alternative idea?

Would it be possible for you to use a dual playfield display? Then you
can displayscroll the front and back playfields separately.

The only other thing I can think of ATM is doing the scroll in software
onto another bitmap and then displaying the main playfield and blits on
top of that. But that would be pretty slow.



|) /\ \/ ][ |) |\/| c |\/| ][ |\| |\| | dave@blitz-2000.co.uk
http://members.nbci.com/david_mcminn | ICQ=16827694
Sea Wars Episode 1: The Plankton Menace. A story of good and evil
featuring Loch Seawater and Marsh Wader

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