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Operation (Compaq Tru64 UNIX)
PowerStorm 300 AGP and 300/350 PCI Graphics Controllers 7–5
7.3 Using OpenGL
This section describes the PowerStorm OpenGL driver, which is designed to optimize
OpenGL performance on Compaq Professional Workstations. This section includes the
following topics:
•
Using OpenGL Applications, for users running applications developed with OpenGL
•
Developing OpenGL Applications, for users developing OpenGL applications
7.3.1 Using OpenGL Applications
This section provides information for using OpenGL applications on the Compaq Tru64
UNIX platform. This section includes the following topics:
•
OpenGL Visual Support, describing the available visuals and their properties
•
Indirect Contexts, GLXPixmaps, and the Software Renderer, describing how to enable
GLXPixmap rendering capabilities
7.3.1.1 OpenGL Visual Support
Unlike Windows NT, Tru64 UNIX does not include a generic OpenGL driver as a fall
back to the hardware. On Windows NT, the generic OpenGL driver provides a software
fallback for pixel formats (equivalent to visuals on the X Window System) not provided by
the hardware-accelerated driver.
For example, on Windows NT, if an application requests a WGL pixel format with an
alpha buffer, and the hardware-accelerated driver does not support that pixel format, then
the generic software OpenGL driver will be employed, albeit at a significant performance
penalty.
On Tru64 UNIX, if a GLX visual with the desired capabilities is not available from the
PowerStorm 300/350 driver, the application must either fallback to another supported
visual or give up and exit. A benefit of this requirement is that all OpenGL applications
that do find a suitable visual are guaranteed to be using a hardware-accelerated visual.
The visuals supported by the PowerStorm 300 PCI graphics controller and PowerStorm
350 PCI graphics controller are listed in Table 7-1 and Table 7-2, respectively. Notice that
the PowerStorm 350 PCI graphics controller supports twice as many visuals. This is due
to its quad-buffering (stereo) support.