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Subject: 
Re: Mac Brick CAD and the Imerial Star Destroyer
Newsgroups: 
lugnet.cad.dev.mac
Date: 
Tue, 25 May 2004 04:51:03 GMT
Reply-To: 
cjmasi@*nogarbageplease*rcnSTOPSPAM.com
Viewed: 
2691 times
  
Travis Cobbs wrote:
In lugnet.cad.dev.mac, Don Heyse wrote:

Yeah, watch out for that software rendering on the Mac.  It sneeks up on
you.  I know it can switch you over while your program is running, but I
don't know what causes it to happen other than resizing a window.  You
might want to query it about the driver as you build up your display lists
to see if it switches you over to software rendering at some point.


Actually, the same thing can happen in Windows if you resize a window too big
(say 1600x1200) on an older video card.  However, I'm not sure you can tell that
it has switched to software mode on Windows, because as far as I know it is
still being rendered by the video card's OpenGL driver.  I can't see how it
could possibly switch drivers mid-stream because different drivers support
different extensions.  That would mean that an extension that you had been told
was present could disappear.

--Travis

I think this is what Don is refering to.

Using Don's ldgliteargs to 800x537 on my aging 8 MB VRAM machine so
ldglite would launch using the ATi renderer.

GL_VENDOR ='ATI Technologies Inc.'
GL_RENDERER ='ATi Rage 128 Pro OpenGL Engine'
GL_RGBA_BITS: (8, 8, 8, 8)
GL_DEPTH_BITS = 24
GL_STENCIL_BITS = 8

But if I make my window bigger the Apple software renderer kicks in
GL_VENDOR ='Apple'
GL_RENDERER ='Generic'
GL_RGBA_BITS: (8, 8, 8, 8)
GL_DEPTH_BITS = 32
GL_STENCIL_BITS = 8

If I go back to the original size, the ATi driver takes over again.

One of the odd observations is that the screen redraw takes the same
amount of time regardless of the window size (6 s for my caboose
http://users.rcn.com/cjmasi/caboose_m.dat) but rotating the model is
_much_ smoother when the ATi driver is active. Maybe it is just a window
size thing, but I don't think so. It only takes a few pixels bigger to
get the drivers to switch. You know what the nonprogramer* is
thinking... in ldglite (maybe MBC too) redrawing the model is not
hardware accelerated on my Mac (maybe yours too) even when the hardware
renderer is active.

The GL stuff that is quoted above is taking from my console window.

With MBC the the size of the window does not effect the smoothness of
the rotation nearly as much, but I have no way of know where the
rendering is occuring.

Chris

*That is me if it wasn't clear enough.



Message is in Reply To:
  Re: Mac Brick CAD and the Imerial Star Destroyer
 
(...) Actually, the same thing can happen in Windows if you resize a window too big (say 1600x1200) on an older video card. However, I'm not sure you can tell that it has switched to software mode on Windows, because as far as I know it is still (...) (20 years ago, 21-May-04, to lugnet.cad.dev.mac)

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