Re: [AD] Fw: Acquire/Release speed issue

[Angelo Mottola <a.mottola@xxxxxxxxxx>]

> Angelo, what is the situation under MacOS X?  I see the driver 
> implements the
> create_video_bitmap method, so you're likely on the Windows side.  But 
> it
> doesn't seem to reuse the screen for the first video bitmap with the 
> same
> dimensions?  If so, how does it support page flipping?

When I implemented the OSX video bitmaps support the whole Carbon 
Quickdraw hw acceleration issue was still somewhat unknown for me. I 
modeled after the QNX port, but eventually there was some problem with 
reusing the screen IIRC...
In any way, I left the thing untouched just to make the OSX port to 
support at least page flipping. Which is not exactly page flipping, but 
actually is double buffering.
I know this is plain wrong, but a lot of programs expect page flipping 
to work in some way (even a lot of the Allegro examples), but given the 
fact I now have a more complete view of the OSX environment, I can say 
the OS doesn't support any 2d hw acceleration directly. You *always* 
just work on buffers, then the window server composites the windows 
using OpenGL. Or you can use OpenGL directly. But if you don't, there 
is no way to obtain hw acceleration nor any hardware feature, as you're 
really working on a buffer in system memory. The Quickdraw API I used 
was created with older MacOS versions in mind, where acceleration was 
possible. But under OSX it doesn't work as it was meant to, I've 
discovered this later.
The current OSX show_video_bitmap() hook simply copies another video 
bitmap (created using NewGWorld, which in Quickdraw should create a 
surface using VRAM or AGP accessible memory, but as I discovered later 
it just creates it out of normal RAM) onto the screen using CopyBits 
(which in Quickdraw should be accelerated).
As I explained though, this is just an hack to emulate page flipping, 
and without acceleration anyway.

What should I do? Should I remove the whole video bitmaps support from 
OSX, as it's not really following the docs?

--
Angelo Mottola
a.mottola@xxxxxxxxxx