The Mesa Cell driver is part of the Gallium3D architecture.
Tungsten Graphics is leading the project. Two phases are planned. First, to implement the framework for parallel rasterization using the Cell SPEs, including texture mapping. Second, to implement a full-featured OpenGL driver with support for GLSL, etc.
The Cell driver source code is on the gallium-0.1 branch of the
git repository.
To build the driver you'll need the IBM Cell SDK (version 2.1 or 3.0).
To use the driver you'll need a Cell system, such as a PS3 running Linux,
or the Cell Simulator (untested, though).
If using Cell SDK 3.0, first edit configs/linux-cell and add
-DSPU_MAIN_PARAM_LONG_LONG to the SPU_CFLAGS.
To compile the code, run make linux-cell.
To use the library, make sure LD_LIBRARY_PATH points the Mesa/lib/
directory that contains libGL.so.
Verify that the Cell driver is being used by running glxinfo
and looking for:
OpenGL renderer string: Gallium 0.1, Cell on Xlib
Rasterization is parallelized across the SPUs in a tiled-based manner. Batches of transformed triangles are sent to the SPUs (actually, pulled by from main memory by the SPUs). Each SPU loops over a set of 32x32-pixel screen tiles, rendering the triangles into each tile. Because of the limited SPU memory, framebuffer tiles are paged in/out of SPU local store as needed. Similarly, textures are tiled and brought into local store as needed.
More recently, vertex transformation has been parallelized across the SPUs as well.
As of February 2008 the driver supports smooth/flat shaded triangle rendering with Z testing and simple texture mapping. Simple demos like gears run successfully. To test texture mapping, try progs/demos/texcyl (press right mouse button for rendering options).
If you're interested in contributing to the effort, familiarize yourself with the code, join the mesa3d-dev mailing list, and describe what you'd like to do.