Paul Berry
b50c0feb2c
When possible, glReadPixels calls are performed using the hardware
blitter. However, according to the Ivy Bridge PRM, Vol1 Part4,
section 1.2.1.2 (Graphics Data Size Limitations):
The BLT engine is capable of transferring very large quantities of
graphics data. Any graphics data read from and written to the
destination is permitted to represent a number of pixels that
occupies up to 65,536 scan lines and up to 32,768 bytes per scan
line at the destination. The maximum number of pixels that may be
represented per scan line’s worth of graphics data depends on the
color depth.
With an RGBA32F color buffer (which has 16 bytes per pixel) this
imposes a maximum width of 2048 pixels.
To make matters worse, if the pitch of the buffer is 32k or greater,
intel_miptree_map_blit's call to intelEmitCopyBlit will overflow
intelEmitCopyBlit's src_pitch and dst_pitch parameters (which are
16-bit signed integers).
We can conveniently avoid both problems by avoiding the readpixels
blit path when the miptree's pitch is >= 32k.
Fixes gles3conform "half_float" tests when the buffer width is greater
than 2048.
Reviewed-by: Eric Anholt <eric@anholt.net>
Tested-by: Ian Romanick <ian.d.romanick@intel.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.