>
> I was wondering if anyone can explain why programs such as
> POV Ray only work on Qx0 machines.
Mainly because they check whether they ARE running on such a machine, and, when not, just give up.
The reason:
The Qx0 on the one side, and QPC/QXL on the other side have incompatible High colour modes.
The Qx0 has mode 33, QPC/QXL mode 32. In both cases, when you look at the data representing on pixel on the screen, the colour is coded on one "word" (16 bits).
For mode 32, this is coded as:
gggbbbbb rrrrrggg
where for mode 33 this is coded as:
gggggrrr rrbbbbbw
(where W is 1 if any two of the highest bits for the other colours are 1)
In many applications that doesn't matter, since, when writing to the screen they just use the OS (SMSQ/E) which handles the "painting" onf th epixels correctly.
Other software, however, such a POV, will write to the screen directly, this writing a word for each pixel into the screen memory.
To avoid getting funny colours all over the screen, this software checks whether it runs on a machine that has the corresponding mode - if not, it gives up.
Other software is a bit more intelligent (accomodating?) and paints the screen corresponding to the mode it runs in...
>
I can see that the
> colours would be incorrect on other platforms such as QPC,
> but don't understand why they refuse to run. With all this
> talk of maintaining OS compatibility on different platforms
> it seems strange that a lot of new software has major
> problems dealing with something new like GD2.
As there are only really 2 major high colour screen formats, and as there only thing one really has to do is some byte shifting, software could/should be written to take both formats into account - IF you really have to write to the screen directly!
Wolfgang
