HP c8000 manual New environment variables as of release

overview of OpenGL

environment variables

. 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 = Object Coordinates and EC = Eye Coordinates. For details on the lighting space, see the sections “Lighting Space” and “Optimization of Lighting” found in Chapter 5. This option is available only for the HP Visualize fx family of graphics devices.

HPOGL_TXTR_SHMEM_THRESHOLD (HP Visualize fx family only)

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 to 10241024 bytes. This variable should be set to the byte size desired for shared memory usage. This option is available only for the HP Visualize fx family of graphics devices.

new environment variables as of release 1.05

The performance of HP OpenGL double buffering has been improved for Release 1.05 of HP’s implementation of OpenGL 1.1. With this performance enhancement, there is a low probability that minor image tearing may be visible during buffer-swap operations. The majority of OpenGL applications will see no difference in the visual quality of double buffering. However, this tearing may be noticed by some OpenGL applications that render simultaneously to multiple windows. Two environment variables can be set in an application environment to control whether or not the new faster buffer swapping method is in effect:

HPOGL_DSM_ENABLE_FAST_BUFFER_SWAP

When set to any non-NULL value, the new or faster double buffering method will be used. (This is the default behavior and does not need to be set except to override glHint as discussed below)

HPOGL_DSM_DISABLE_FAST_BUFFER_SWAP

When set to any non-NULL value, the old or slower double buffering method will be used.

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