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hp-PHIGS Graphics Performance
Optimized vs. Normal 3D Performance
Performance Optimized For: Factors Affecting Performance:
Rendering Conditions
• Light Sources:
o Best: up to 8 directional light
sources, plus ambient
o Good: a mixture of up to 8
directional and positional light
sources, plus ambient
• Directional eyepoint, set via:
o pescape_u230/pgse_u3 (C),
pue230/pus003 (FORTRAN)
• Back face culling off, or back face culling
on with supplied geometric normals
• View clipping on, set via:
o pset_view_rep (C), psvwr
(FORTRAN)
• True colour mapping in a direct colour
environment
• Isotropic modeling matrix (angle-
preserving)
• A total of more than 8 directional and
positional light sources cause a noticeable
performance degradation
• Picking (including direct pick and logical
device picking)
• Any of the following ways of heavily
interleaving changes:
o Frequent attribute changes (e.g.,
frequent changes of line colour)
relative to the number of primitives
being drawn
o Frequent changes of the type of
primitive (e.g., switching between
Fill Areas and Polylines at a high
frequency)
o Frequent changes of vertex format
(i.e., the data being supplied with
each vertex)
o Frequent changes of modal state,
such as:
HLHSR mode or ID
Colour mapping method
Light sources enabled
Depth cueing state
o Frequent switching between two or
more active workstations
o Frequent mixing of Xlib and hp-
PHIGS calls
• Redundant or unnecessary setup (e.g.
setting attributes that are not relevant to the
primitives being drawn)
• Model clipping on
• HLHSR in software via PowerShade (on
unaccelerated graphics devices)
Graphics Administration Guide for HP-UX 10.20
Page 109