[chimera-dev] Chimera binary code issue

[Tom Goddard]

Hi Jupiter,

   Thanks for the details.  Mesa DRI (direct rendering infrastructure) 
allows Mesa to use hardware graphics acceleration, and I would expect it 
to be faster.  You said you didn't have any graphics on the computer you 
are using.  Are you sure about that? You know modern Intel CPUs often 
have an Intel graphics processsor on the same chip.  According to the 
mesa xlib web page

     http://www.mesa3d.org/xlibdriver.html

" Effectively, the Xlib driver converts all OpenGL rendering into Xlib 
calls."  I would expect that to be incredibly slow, maybe 100 times 
slower than rendering with a graphics card.  It may be especially bad 
with Chimera because Chimera wants to use lots of OpenGL capabilities.

   If you wish to pursue this further please use Chimera menu entry Help 
/ Report a Bug... on the computer of interest.  Report a bug with both 
the Mesa DRI driver and another with the Mesa Xlib driver.  This will 
give us all the info about your system and what OpenGL Chimera is trying 
to use.

     Tom

> Hi Tom,
>
> Thanks for your response. Let me clarify it in my following embedded comments.
>
> On 3/12/13, Tom Goddard <goddard at sonic.net> wrote:
>> Hi Jupiter,
>>
>>     Chimera tries to use modern OpenGL features: shaders, vertex buffers,
>> instancing, ....  It disables some of those features known to be buggy
>> in mesa.  If you start chimera --debug-opengl you can disable more
>> OpenGL features with a start-up dialog.
> I see the debug dialog, but did not change things if I disable some
> opengl features.
>
>>     You said in your first email that Chimera ran with "very poor
>> performance when using mesa".  It would be helpful to give an explicit
>> example (e.g. opening PDB yyyy the model rotates at about z frames per
>> second).
> Chimera can be used in mesa, but only in mesa DRI driver.
>
> If I click Tools->Demo-> COX Inhibitors Demo in Mesa DRI driver, a 3D
> structure can rotate relatively good. But if I changed to use Mesa
> Xlib driver, the performance is significantly deteriorated, the 3D
> structure could no longer rotate, instead of drawing line by line.
>
> This was my main question why it could perform 3D rending in Mesa DRI
> driver, but very poor in Mesa xlib driver. Most OpenGL applications
> work in both mesa DRI and xlib drivers. Is there any workarounds we
> could do to run Chimera in mesa Xlib driver?
>
>>     Does your X11 VNC render OpenGL using the client graphics driver?  It
>> might just send the OpenGL to the client (ie. displaying) system in
>> which case performance would depend on the graphics driver of that
>> system.  Performance can be dismal in such a situation because OpenGL
>> queries have to make a roundtrip across the network connection.
> Let me clarify it, I am doing the testing in a local machine, running
> Chimera with either Mesa DRI driver or xlib driver. No VNC connection,
> no network issues. The  hardware is normal graphic driver using mesa
> DRI or Xlib. There was no hardware acceleration, no GPU.
>
> Thank you.
>
> Kind regards,
>
> Jupiter
>

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