Re: OpenGL and hardware acceleration

Michael Gold <[email protected]> Wed, 09 Jul 2008 11:15:25 -0800
Newsgroups gmane.games.devel.opengl
Organization Fat City Network Services, San Diego, California
Message-ID <[email protected]>
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Most modern hardware implementations accelerate the 3D rendering paths,
to varying degrees.&nbsp; For example glVertex is "accelerated" but other
paths may be "more accelerated", e.g. VBOs and display lists, depending
on both the implementation and your usage.<br>
<br>
Less certain, but certainly implemented on some platforms, include
things like the pixel path and accumulation operations.<br>
<br>
Unlikely to be accelerated: selection and feedback modes, evaluators.<br>
<br>
But you must understand that "accelerated" is a relative term.&nbsp; Some or
all of the above may be natively supported, emulated by lower level
hardware primitives, implemented in software, or a hybrid involving one
or more of these approaches.&nbsp; And, which path you hit may depend on
other state combinations and your usage.&nbsp; Also, it depends on the card;
a low end/low cost card may "accelerate" an operation but you might be
able to do it faster in the application.&nbsp; The reality is there are
simply too many factors involved to make a simple boolean determination
of whether a particular operation, given a particular set of inputs and
the current state vector, is "accelerated".<br>
<br>
Ultimately all you can do is measure the performance of modes you wish
to use and make decisions based on the actual observed performance.&nbsp;
This link is fairly old but the problem and solution it describes are
timeless.<br>
<br>
&nbsp;&nbsp;&nbsp; <a class="moz-txt-link-freetext" href="http://www.berkelium.com/OpenGL/isfast">http://www.berkelium.com/OpenGL/isfast</a><br>
<br>
I can say with a high degree of certainly that any time spend perusing
the Mesa source in hopes of gleaning useful information about hardware
implementations is a waste of time.<br>
<br>
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Author: Michael Gold
  INET: [email protected]

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