Re: [MiNT] XaAES sources for FreeMiNT 1.16.3

[Johan Klockars <johan@klockars.net>]

> To continue on my example, the DirectX API on Windows allows this, in an
> official and documented way. The API describes precisely what features are
> available or not from the driver. It describe also the pixel formats, the
> line offsets... Every graphics card is different, but there are not so much
> pixel formats. They are regrouped into families.

Not so different from our situation, except that we don't have as many features.

I do know that some of those missing features, such as a way to switch
to another prepared frame buffer in an instant, are very important for
games etc.

> So developers are happy.
> If they want to do low-level stuff for any reason, even if this can be slow,

As they can on our machines, only "slow" is in a different league (;-).

Unlike under Windows (for example), the VDI has always allowed
unrestricted access to the entire screen (via the VDI functions, that
is).
If you don't care about the speed, even the current VDI blit
functionality is usable...

> If the VDI had allowed something like this, we may had seen more games using
> the VDI.

Except, of course, that writing directly to the screen is not "using
the VDI".  ;-)

Whether it is the VDI that gives you the pointer to the frame buffer
or the XBIOS is besides the point. On some of our existing
hardware/platforms, it just is not possible to do that at all in a
safe/useful way.

I thought the main point for games was speed, not direct write access
to the frame buffer. If you get better performance some other way,
would that not be preferable?

As I said in another email, I'm very interested in talking about these
issues. I have tried asking several times before over the years for
input from game developers etc, without success.

The important thing should be to create something useful, right?

If you (not you personally) persist in only requesting things that the
VDI can not usefully provide, there's no point for me to be in this
discussion. I don't write, nor care about, XBIOS code or games that do
not use the VDI to access the screen.
See my previous email for ideas about what could be done.

> Oh, just for completeness, DirectX allows direct access to the frame buffer
> only in fullscreen, not windowed. This is another nice feature. The

I'd say it is a requirement, not a feature. You should never allow
direct access to the entire screen when there are other applications
using it. That the VDI does is one of its greatest faults, IMHO.

/Johan