[Freeciv-Dev] Re: (PR#7297) Caching map canvas

["Jason Short" <jshort@xxxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=7297 >

On Fri, 23 Jan 2004, Raimar Falke wrote:

>
> <URL: http://rt.freeciv.org/Ticket/Display.html?id=7297 >
>
> On Fri, Jan 23, 2004 at 11:06:12AM -0800, Raimar Falke wrote:
> > Advantages:
> >   - fast change of map origin
> >   - pixel based position of the view quite easy
> >
> > Disadvantages:
> >   - large memory usage
>
> Minimal usage:  40* 25*30*30  *1 Byte=900kb
> Maximal usage: 200*100*64*32*9*3 Byte=1.1gb
> Typical non-iso:80* 50*30*30  *2 Byte=7.2mb
> Typical iso:    80* 50*64*32*9*2 Byte=145mb
>
> So this pretty much makes the plan non-usable. It would have been
> nice.

Iso isn't 64x32.  It's 64x32/2, since it only occupies half that area; 72
Mb.  And typical iso will only be 1/3 of that since with a classical
topology you only need 3 backing stores.  24 Mb?  Still a lot.

One alternative is to have just one backing store, and wrap it when you
draw it.  Up to 4 draws must be done to put it on the screen.  Now you
only have to draw tiles once to the backing store.  You'll still get them
showing up on screen multiple times, though.  And you have to have
transparency in your backing store, which I'm told makes for much slower
drawing.

jason