Roland Scheidegger
f621015cb5
This proved to be tricky, the problem is that after selection/mirroring we cannot calculate reasonable derivatives (if not all pixels in a quad end up on the same face the derivatives could get "randomly" exceedingly large). However, it is actually quite easy to simply calculate the derivatives before selection/mirroring and then transform them similar to the cube coordinates (they only need selection/projection, but not mirroring as we're not interested in the sign bit, of course). While there is a tiny bit more work to do (need to calculate derivs for 3 coords instead of 2, and additional selects) it also simplifies things somewhat for the coord selection itself (as we save some broadcast aos shuffles, and we don't need to calculate the average vector) - hence if derivatives aren't needed this should actually be faster. Also, this has the benefit that this will (trivially) work for explicit derivatives too, which we completely ignored before that (will be in a separate commit for better trackability). Note that while the way for getting rho looks very different, it should result in "nearly" the same values as before (the "nearly" is only because before the code would choose the face based on an "average" vector and hence the derivatives calculated according to this face, where now (for implicit derivatives) the derivatives are projected on the face selected for the first (top-left) pixel in a quad, so not necessarly the same face). The transformation done might not quite be state-of-the-art, calculating length(dx,dy) as max(dx,dy) certainly isn't neither but this stays the same as before (that is I think a better transform would _somehow_ take the "derivative major axis" into account so that derivative changes in the major axis wouldn't get ignored). Should solve some accuracy problems with cubemaps (can easily be seen with the cubemap demo when switching wrapping/filtering), though we still don't do seamless filtering to fix it completely (so not per-sample but per-pixel is certainly better than per-quad and already sufficient for accurate results with nearest tex filter). As for performance, it seems to be a tiny bit faster too (maybe 3% or so with cubemap demo). Which I'd have expected with nearest/nearest filtering where this will be less instructions, but the difference seems to actually be larger with linear/linear_mipmap_linear where it is slightly more instructions, probably the code appears less serialized allowing better scheduling (on a sandy bridge cpu). It actually seems to be now at least as fast as the old path using a conditional when using 128bit vectors too (that is probably more a result of testing with a newer cpu though), for now that old path is still there but unused. No piglit regressions. Reviewed-by: Jose Fonseca <jfonseca@vmware.com>
File: docs/README.WIN32 Last updated: 23 April 2011 Quick Start ----- ----- Windows drivers are build with SCons. Makefiles or Visual Studio projects are no longer shipped or supported. Run scons osmesa mesagdi to build classic mesa Windows GDI drivers; or scons libgl-gdi to build gallium based GDI driver. This will work both with MSVS or Mingw. Windows Drivers ------- ------- At this time, only the gallium GDI driver is known to work. Source code also exists in the tree for other drivers in src/mesa/drivers/windows, but the status of this code is unknown. General ------- After building, you can copy the above DLL files to a place in your PATH such as $SystemRoot/SYSTEM32. If you don't like putting things in a system directory, place them in the same directory as the executable(s). Be careful about accidentially overwriting files of the same name in the SYSTEM32 directory. The DLL files are built so that the external entry points use the stdcall calling convention. Static LIB files are not built. The LIB files that are built with are the linker import files associated with the DLL files. The si-glu sources are used to build the GLU libs. This was done mainly to get the better tessellator code. If you have a Windows-related build problem or question, please post to the mesa-dev or mesa-users list.