Eric Anholt
38bad7677e
The user-space suballocator that was used avoided relocation computations by using the general and surface state base registers and allocating those types of buffers out of pools built on top of single buffer objects. It also avoided calls into the buffer manager for these small state allocations, since only one buffer object was being used. However, the buffer allocation cost appears to be low, and with relocation caching, computing relocations for buffers is essentially free. Additionally, implementing the suballocator required a don't-fence-subdata flag to disable waiting on buffer maps so that writing new data didn't block on rendering using old data, and careful handling when mapping to update old data (which we need to do for unavoidable relocations with FBOs). More importantly, when the suballocator filled, it had no replacement algorithm and just threw out all of the contents and forced them to be recomputed, which is a significant cost. This is the first step, which just changes the buffer type, but doesn't yet improve the hash table to not result in full recompute on overflow. Because the buffers are all allocated out of the general buffer allocator, we can no longer use the general/surface state bases to avoid relocations, and they are set to 0 instead.
WindML Driver for Mesa 4.0
Requirements
------------
Tornado 2 + WindML, Cumulative Patchs are recommended.
I suppose you have a valid WindML installation. Double buffer hardware
gives better performance than double buffer software so if you can
compile your WindML driver with this option, just do it. I/O
redirection is adviced in target server.
Tested on
---------
During the development, my main target was a CoolMonster:
- Video card: CT69000
- CPU: PENTIUM 266MHz
and my host a Windows NT + Tornado 2.
Installation
------------
1. Mesa sources must be in root directory (C:\)
2. Add the following line to your torVars.bat:
set MESA_BASE=C:\Mesa
OR copy the new torVars.bat in your bin path:
c:/Mesa/src/ugl/tornado/torVars.sample ->
/mnt/nt/Tornado/host/x86-win32/bin/torVars (for example)
3. In a command prompt:
$ torVars
$ cd c:\Mesa
$ make -f Makefile.ugl CPU=PENTIUM
Take a long while...
5. Include all the files from ugldemos folder to build some downloadable
application modules
4. Download UGL/Mesa object files on target
For example via the WindShell:
ld < c:\Tornado\target\lib\objMesaGL.o
ld < c:\Tornado\target\lib\objMesaUGL.o
ld < c:\Tornado\target\lib\objMesaGLU.o
ld < c:\Tornado\target\lib\objGLUTshapes.o
ld < c:\Tornado\target\lib\objMesaOS.o
You can put the previous lines in a file and use:
< filename
6. Download the application modules.
7. In WindShell, run:
-> uglalldemos
During the show some messages will appear, it provides some useful
information on key management.
Coding
------
Sample Usage:
In addition to the usual ugl calls to initialize UGL, (may be find an
input driver), you must do the following to use the UGL/Mesa interface:
1. Call uglMesaCreateContext() to create a UGL/Mesa rendering context,
given the display format.
2. Call uglMesaMakeCurrent() to bind the UGL/Mesa buffers to an
UGL/Mesa Context and to make the context the current one.
3. Make gl* calls to render your graphics.
4. Use uglMesaSwapBuffers() when double buffering to swap front/back buffers.
5. Before the UGL is destroyed, call MesaDestroyContext().
6. Before exiting, call if required uglEventQDestroy and then
uglDeinitialize();
Limitations
-----------
I found the following limitations in my driver :
- Color Indexed management is only in 8 bits
- It's possible to mix UGL/OpenGL application with a software
double buffer
Modifications
------------
New files in Mesa:
- Makefile.ugl
- rules.windmlmesa
- docs/README.UGL
- include/GL/uglmesa.h
- si-glu/Makefile.ugl
- src/Makefile.ugl
- src/ugl/torGLUTShapesInit.c
- src/ugl/torMesaUGLInit.c
- src/ugl/ugl_api.c
- src/ugl/ugl_dd.c
- src/ugl/ugl_glutshapes.c
- src/ugl/ugl_line.c
- src/ugl/ugl_span.c
- src/ugl/ugl_tri.c
- src/ugl/uglmesaP.h
- ugldemos/*
Modified files in Tornado 2.0:
- c:\Tornado\host\x86-win32\bin\torVars.bat
rem Command line build environments
set WIND_HOST_TYPE=x86-win32
set WIND_BASE=C:\Tornado
set MESA_BASE=C:\Mesa
set PATH=%WIND_BASE%\host\%WIND_HOST_TYPE%\bin;%PATH%
- c:\Tornado\target\config\comps\VxWorks\01uglmesa.cdf
- c:\Tornado\target\h\GL\*
Todo
----
- GCC 2.96, ASM compilation
Thanks to:
----------
Precision Insight team for their great job around Mesa, XFree, and DRI.
Wind River Systems to take me as an intern.
Stephane Raimbault
<stephane.raimbault@windriver.com>
<stephane.raimbault@deesse.univ-lemans.fr>
July 24, 2001