[iyonix-support] Re: 16 colour screen modes on the Iyonix

In message <4e3d7a04a8lists-nospam@xxxxxxxxx>
          Paul Vigay <lists-nospam@xxxxxxxxx> wrote:

> Is there any way to simulate 16 colour screen modes on the Iyonix?
> 
> I'm trying to convert some old games to 32-bit compatibility, but a
> couple use 16 colour screen modes with palette switching to obtain
> animation effects.
> 
> Whilst in terms of screen plotting etc., they seem to work when converted
> to 256 colours, the palette switching routines don't work in 256 colours
> which means the graphics and colours all go to pot. :-(

How about redirecting the program's graphics output to a screen-sized 4 bit
sprite - either using VDU redirection or by altering the program's screen
memory pointer to point to the sprite image. Then plot the sprite to the
screen using a colour translation table - the translation table being built
from the screen palette of the original 4 bit mode.

Therefore when the game does palette switching, you alter the translation
table to reflect this and on the next sprite plot, the different colours
are plotted.

-- 
Rik Griffin
Software Engineer, Denbridge Marine Ltd
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