Environment Variables

HPOGL_ENABLE_MIT_SHMEM When rendering locally using the VM Driver, this variable allows the server and client to look at the rendering buffer at the same time. This variable has no effect through DHA. It merely eliminates the data transfer for XPutImage() that is done by VMD. This only offers a performance improvement on simple wireframes. Under most circumstances, it does not provide any performance improvements.

HPOGL_FORCE_VMD This variable forces clients to render through the VMD. This variable can be used as a temporary fix and/or a diagnostic. You should set this variable when a rendering defect in the hardware device driver is suspected. When this variable is set, rendering speed will slow down. If rendering is identical in both hardware and software, then this may indicate a problem in the application code.

HPOGL_LIB_PATH This variable can be used to load OpenGL driver libraries from a directory outside the standard LIB_PATH. This variable should be set to the actual directory the libraries are in, with or without a trailing '/'.

HPOGL_LIGHTING_SPACE This variable allows the user to specify the coordinate space to be used for lighting. By default, HP's implementation of the OpenGL will select the lighting space. Possible values are:

HPOGL_LIGHTING_SPACE=OC
HPOGL_LIGHTING_SPACE=EC

where OC equals Object Coordinates and EC equals Eye Coordinates. For details on the lighting space, see the sections "Lighting Space" and "Optimization of Lighting" found in Chapter 5.

HPOGL_TXTR_SHMEM_THRESHOLD This variable sets a fence for the use of process memory vs. shared memory. Any 2D or 3D texture that has a size greater than or equal to the threshold set is stored in shared memory. The initial value is set ot 1024×1024 bytes. This variable should be set to the byte size desired for shared memory usage.

HPOGL_ALLOW_LOCAL_INDIRECT_CONTEXTS By default, if an indirect context is requested for a local HP display connection, a direct context will be created instead because the performance will be much better. This variable may be set if a need arises to really create a local indirect context.

HPOGL_FORCE_VGL This variable can be set to force HP's Virtual GL (VGL) rendering mode using VMD. This differs from HPOGL_FORCE_VMD in that the GLX Visual list and other GLX extension information is not retrieved from the GLX Server extension, but is rather synthesized from standard X Visual information and the capabilities known to exist in VMD.