Purpose
Use Set HLHSR Identifier to insert a Set HLHSR Identifier structure element into the open structure following the element pointer or replace the element pointed at by the element pointer with a Set HLHSR Identifier structure element, depending on the current edit mode. During structure traversal, the graPHIGS API sets the current Hidden Line/Hidden Surface Removal (HLHSR) identifier entry of the graPHIGS traversal state list to the specified parameter.
The application uses this value when creating subsequent output primitives in a view with a HLHSR mode other than OFF.
If the workstation does not support the specified HLHSR identifier or the specified identifier is outside the allowable range, then the HLHSR identifier defaults to a value of 0. In a view with HLHSR mode set to OFF, this value is ignored and has no affect on the visualization of primitives.
HLHSR processing is often implemented by use of a z-buffer and a frame buffer. The following table summarizes the effect of the various HLHSR identifiers on the z- buffer and the frame buffer:
| Table 3-1. HLHSR Processing: Summary of when the frame buffer and the z-buffer are updated. | ||
|---|---|---|
| z-buffer | Frame buffer | |
| 0=Visualize if not hidden | Zprim >= Zbuf | Zprim >= Zbuf |
| 1=Visualize if hidden | Zprim < Zbuf | Never |
| 2=Visualize always | Always | Always |
| 3=Not Visualize | Never | Zprim >= Zbuf |
| 4=Face-dependent Visualization | ||
| Front-facing Areas | Zprim >= Zbuf | Zprim >= Zbuf |
| Back-facing Areas | Zprim > Zbuf | Zprim > Zbuf |
| 5=No Update | Never | Never |
| 6=Greater than | Zprim > Zbuf | Zprim > Zbuf |
| 7=Equal to | Zprim = Zbuf | Zprim = Zbuf |
| 8=Less than | Zprim < Zbuf | Zprim < Zbuf |
| 9=Not Equal | Zprim <> Zbuf | Zprim <> Zbuf |
| 10=Less than or Equal to | Zprim <= Zbuf | Zprim <= Zbuf |
Note: The actual update of the z-buffer and/or the frame buffer may be prohibited by the use of the z-buffer protect mask and the frame buffer protect mask.
Language Bindings
| pset_hlhsr_id (hlhsr_id) |
| PSHRID(hrid) |
Errors
Related Subroutines