speed of glReadPixels()

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Hansong Zhang (zhangh++at++cs.unc.edu)
Fri, 8 Nov 1996 14:22:16 -0500 (EST)

Hi,

I did statistics for glReadPixels() on IR. The result shows that
reading a 512x512 area takes about 44 milliseconds, which seems
to long. Could anybody confirm or correct this number (or give me your
results for other resolutions)? I used format GL_RED and type
GL_UNSIGNED_BYTE.

According to OpenGL man pages, pixel transfers seem always to involve
converting to and from floating point representation. Is there anyway
to bypass the type conversion (and can this speed up the transfer?)

Thanks!

Hansong

-------------------------------------------------------------
Hansong Zhang \ zhangh++at++cs.unc.edu
Walkthrough Group \ http://www.cs.unc.edu/~zhangh
Department of Computer Science \ (919)962-1835 (O)
UNC-Chapel Hill \ (919)914-3973 (H)

"I create abstract systems from pure information, Albert. I'm
a *programmer*... Quantum nonlocality is a bug." -- God
-------------------------------------------------------------

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