Keith Whitwell
79a7ddb57a
Fixes two issues - firstly for mipmap levels with one or more
dimensions smaller than tilesize, the code was sampling off the edge
of the texture (but still within the tile).
Secondly, in the linear_mipmap_linear case, both the default code and
new fastpath were incorrect. This change fixes the fastpath and adds
a comment to the default path, which still needs to be fixed.
Basically the issue is that the coordinates in the smaller texture
level are/were being computed by just dividing thecoordinates from the
larger texture level by two, as in:
x0[j] /= 2;
y0[j] /= 2;
x1[j] /= 2;
y1[j] /= 2;
The issues with this are signficant. Initially x1 is most often equal
to x0+1, but after this, it will likely be equal to x0, so we will not
actually be performing the linear blend within the smaller mipmap.
The fastpath code avoided this (recalculated x1), but was still using
the weighting factors from the larger mipmap level (xw, yw), which
were incorrect.
Change the fastpath code to do two full, independent linear samples of
the two mipmap levels before blending. The default code needs to do
the same thing.
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