On 07/09/2013 11:20 PM, Andy Li wrote:
Hello everyone,
I have some questions regarding to OSMesa.
I am currently working on a project which I have to use Mesa on an
embedded system.
My current goal is to port the base functions over to the embedded
system, so that I can draw a line on a provided VGA screen.
Since the embedded system I am using does not contain a GPU, therefore I
have decided to use OSMesa for rendering process.
I am wondering if there are any documentations/ specifications for OSMesa?
End users of OSMesa generally get by on the comments in osmesa.h and the
example programs. But you're working on the driver implementation side.
Anyone know which are the base functions that OSMesa used for the
rendering process?
I don't know what you mean by base functions. In Mesa/master git, the
OSMesa can either be used with the legacy swrast driver or with the
gallium softpipe/llvmpipe drivers.
I have looked into src/mesa/swrast/s_lines.c and s_drawpix.c and trying
to figure out how the code works, am I in the right direction?
That code is used by the legacy OSMesa driver, but it's also used by the
old Xlib driver too.
Moreover, for example, if I found a drawpix() function, how do I know if
OSMesa actually used this function during rendering process? Is there
any tool/debugger I can use to confirm my findings?
One would normally set a breakpoint on the function in gdb or another
debugger.
Let's take a few steps back here first. You said you want to display
graphics on your VGA screen. OSMesa will not do that for you.
OS=Off-Screen. The whole point of OSMesa is to draw into malloc'd
framebuffer memory, rather than drawing to a real/displayed framebuffer.
You could use OSMesa and then do some sort of memcpy of the image into
your devices's actual frame buffer. Is that what you want to do?
-Brian
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