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Thanks No, it’s not, I’ve traced
down the SwapBuffer function , what the swap does is flushing all the commands
in the buffer and rasterizing the vertices to pixels. But I didn’t find anything
related displaying those pixels to the screen. I wonder whether this unknown
displaying function is time driven or event driven. Thanks again for replying. From:
[EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sounds
like he's looking for the Swap function that is defined for each OS
or windowing system api. -Dee
Sharpe Thanks very
much for replying, Brian I'm so sorry,
My English is so poor that I can't even describe my question clear. Here by
"fetching pixels", I didn't mean the function invoked when using "glReadPixels"
explicitly in the application, I don't have a "glReadPixels" call in my
application code. I mean, when
the pipelines have finished rasterizing the vertices and store the pixels
into the framebuffer, all the data are in the memory, nothing is
displayed on the screen, my question is which function is invoked to display those
pixels on the screen so that we can see. I don't know
whether I've show my problem clear or not. I just want to learn how OpenGL
interact with the graphics card and the Operating system through this
great work ( Thanks again.
-----Original
Message----- From: Brian
Paul [mailto:[EMAIL PROTECTED]]
Sent:
2006?10?28? 23:30 To: xiaoshuxing Cc: mesa3d-dev@lists.sourceforge.net Subject: Re:
[Mesa3d-dev] when does mesa read pixels from the color buffer? xiaoshuxing
wrote: > Hello.
Everybody: > > I’ve
been reading the source code of mesa recently, and what puzzles me > a lot is
that I can’t find the function to fetch pixels from the color > buffer
when rendering to the screen. > > I’ve set
several breakpoints in the file >
“s_span.c(_swrast_read_rgba_span,_swrast_get_values, _swrast_get_row)” > ,“wmesa.c(read_rgba_pixels(/spans)_32)”,
which I thought have the most >
possibility to be the right one, but none of them was hit when I was > running
in the debug mode in Visual studio.net 2005. > > So is
there anybody who can give me a clue that which function may be > invoked
when the application reads pixels from framebuffer and render it > to the
screen. > > any help
will be appreciated. One of
several different paths may be taken to implement glReadPixels: 1. The driver
might plug in a hardware-specific ReadPixels routine into
ctx->Driver.ReadPixels(). I don't think the Windows driver does that. 2. The swrast
module can try an optimized routine, like
fast_read_rgba_pixels() (in s_readpix.c) for simple cases. 3. If neither
of those is used, the swrast module will basically use
_swrast_read_rgba_span() to read pixels a row at a time, before applying the
pixel transfer operations. If you stop
your debugger in _mesa_ReadPixels() it should be easy to trace the
path. -Brian ------------------------------------------------------------------------- Using Tomcat but
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