Re: [AD] Problem with screen shearing on MAC OS X

[Runesabre <runesabre@xxxxxxxxxx>]

Thanks a lot, Peter.  I was hoping you would see my
message as you appear to be the Mac guru for Allegro.

> I have one further question - 
are you running full screen or windowed?

I am using GFX_AUTODETECT_FULLSCREEN. (I've used
GFX_QUARTZ_FULLSCREEN as well with similar results) I
couldn't get the windowed mode to work on the MAC
because it wasn't able to allocate all the video
memory I needed at startup with the way I'm currently
doing the client. 

I ran into a similar problem on Linux which was solved
by setting the virtual screen width and height values
on set_gfx_mode() to the size I would need to allocate
the video bitmaps for buffering and art assets.  On
the Mac, however, it would not except any non-zero
value; putting a non-zero value for the virtual screen
parameters would result in a "resolution not supported
error".

> Can you check the Allegro demo game? - at startup
you can select the 
screen update mode. Do you still get tearing with the
demo.

I will fire that up and see what the results are.

>Technically, because OSX does its own offscreen
buffering for windows, 
I think you'd actually get the best performance by
doing 
acquire_screen(), draw directly onto the screen, and
then release_screen(). That 
doesn't help with cross-platform compatibility though.

In my research attempting to track down others with
similar problems, I did see several references to Mac
having built in double buffering.  I am going to
re-work my client to allow it to use the screen
directly as you suggested.  The client is engineered
well enough to allow component differences as long as
the high level game logic remains the same.  I needed
to have a strategy anyways for handling situations
where I can't allocate enough video memory so this
will allow my client more flexibility and if it solves
the Mac problem so much the better!

> Let me know how you get on with the demo game, and
if you can supply 
any code from your main loop that might help me to
determine if you're 
doing anything 'odd'

I will report back my results and what changes were
needed if I can solve them.  If all else fails, I will
work up a stripped down version of my client that
illustrates the problem without all the rest of the
game code cluttering it and email you the code so you
can build it and try it out and see what I might be
doing incorrectly.

Thanks a lot Peter, and again great job on the Mac
port!  I was surprised really at how easily and quick
I was able to go from never having owned a Mac in my
life to buying and porting my entire project (with
networking I might add... that was where the most of
the work in porting went) in one weekend.

Kirk Black


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