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V. RESTRICTIONS
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In some cases, there is confusion over the meaning of the PFD_SUPPORT_GDI
bit in the dwFlags field of the PIXELFORMAT descriptor. ASUS have seen
applications (for instance Open Inventor) which incorrectly assume that if this
flag is set, rendering to bitmaps is supported by the visual. The Installable
Client Driver does not support bitmap rendering so these applications fail. To
enable these applications to work the exporting of PFD_SUPPORT_GDI can
be disabled by setting the following registry variables FALSE. The applica-
tions will then choose a Generic pixel format so using unaccelerated software
rendering to draw to bitmaps.
By default PFD_SUPPORT_GDI is set to TRUE for single buffer formats and
FALSE for double buffered formats.
Note under WindowsNT, Generic pixel formats that support double buffering
and rendering via GDI are mutually exclusive. This is because GDI does not
have the ability to render to the back buffer. ASUS have therefore chosen to set
the default for double buffering, so as to be in line with the Microsoft imple-
mentation. However with care GDI rendering and double buffering may be
mixed, so the latter registry variable will cause PFD_SUPPORT_GDI to be
exported by double buffer formats, should an application benefit from this
added functionality.
•
When running multi-threaded applications it may be necessary to disable the
use of the fast clear planes by setting the environment variable
GLINT_DONT_USE_FCP to TRUE, or by checking the corresponding box
in the control panel applet. This issue arises when more than one context is
being used to render to the same window (e.g. Windows NT 4.0 OpenGL pipes
screen-saver with multiple option selected). If this variable is set then this
disables the use of ASUS proprietary fast clear mechanism that allows the
depth (Z) buffer to be cleared up to 16 times more quickly than normal. Typi-
cally this becomes significant for animation rates of 10Hz or higher in large
windows.
•
On Windows NT 4.0, the standard OpenGL screen savers do not get hardware
acceleration at the 32668 color depth. The problem is due to the fact that the
Microsoft binaries test for a pixelformat with the cColorBits field set to 16 at
this color depth, whereas the pixel formats exported for all our hardware is the
correct value of 15 at this color depth. All other color depths do not suffer from
this bug.
3DExtensions.SupportSingle
3DExtensions.SupportDouble
ASUS 3DP-V500TX
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