Re: [MiNT] Bit-Depth and Graphics stuff....

["Michael Bernstein" <mint@mbernstein.de>]

Hi,

> > No, the way to do this is to first transform the bitmaps to a generic
> > format (such a format already exists in VDI for 8 bit and less), and
> > then transform this generic format to the screen format.
> 
> Is this a good idea in truecolor?
> 
> To be honest, it's not even a good idea in palette modes, because
> performance is just horrible.

You are right if you point out, that this way consumes some CPU power.
But it is the clean way and will work with every hardware.

The result of vq_extnd will show, if you have palette mode (work_out[5])
and the color depth (work_out[4]).

For palette mode with up to 256 colors you should always let the VDI do
the work. Because you dont have informations about the organization of
the video ram, you should allways use the device independant format
and let the VDI transform this bitmap with vr_trnfm to the device
dependant format before copy it to the screen with vr?_cpyfm. This will
allways work on all GEM machines. This is one of the golden rules of
portable GEM application: dont make assumptions about the system. And
this includes also the organization of the graphics card.

For color modes without palette there is a problem because there is no
definition about the organization. If the VDI function vq_scrninfi
exist (check EdDI Cookie), you can query for informations about the
organization of the graphics screen and store your bitmaps in the
format used by the hardware.

You can check TOS.HYP for this informations: http://toshyp.atari.org/

Best regards
Michael Bernstein