Michael Jones (mtj++at++babar)
Tue, 18 Jan 1994 10:38:48 -0800
:1. Why do INTA or RGBA textures look as if they were quantised to 4 levels
with
:4-sample multisampling and to 8 levels with 8-sample multisampling?????
:( Onyx RE2 with 2RM, Performer 1.1, IRIX 5.0.1 )
Since speed is the goal of nearly all IRIS Performer users, we made the
default for all settable modes be those that run fastest on the fastest
graphics machine, the RealityEngine.
The texture subsystem in the RE (same in RE2) runs twice as fast for 16-bit
textures as it does for 32-bit ones. It also supports two 16-bit high-speed
versions if the normal 32-bit texture formats these are:
RGBA as 8-8-8-8 quantized to 4-4-4-4, and,
RGB as 8-8-8 quantized to 5-6-6
When these low-precision formats are used, the texture subsystem will run
at twice the speed. The default in IRIS Performer is to cause incoming
textures to be reformatted into these high-speed internal formats. The
function pfTexFormat specifies how the texture image memory associated
with tex is formatted. format is a symbolic token specifying which format
to set and is PFTEX_INTERNAL_FORMAT, PFTEX_EXTERNAL_FORMAT, or
PFTEX_FAST_DEFINE. type is a symbolic token specifying the format type
appropriate to format. For PFTEX_INTERNAL_FORMAT and PFTEX_EXTERNAL_FORMAT
its values are the same as GL format tokens but with a PFTEX_ prefix.
(This last is from the man page) The default internal format is:
PFTEX_RGB_5 or PFTEX_RGBA_4
but if you don't like the quality just call pfTexFormat and specify
one of:
PFTEX_RGBA_8 or PFTEX_RGB_12 for your textures.
:2. Apparently PFTR_HIGH_QUALITY must be set with pfGStateMode or
pfTransparency
:in order to avoid this "quantised" alpha. Is there a way to set
:this in Performer 1.1? This token does not exist in PF1.1.
:I also looked for a similar method in gl but could not find it.
The choices for transparency are blended or multi-sampled. These are
the "high-quality" and "fast" modes. Set the desired mode directly
using:
PFTR_BLEND_ALPHA or PFTR_MS_ALPHA with pfTransparency().
--Be seeing you, mtj++at++sgi.com 415.390.1455 M/S 7L-590 Michael Jones Silicon Graphics, Advanced Graphics Division 2011 N. Shoreline Blvd., Mtn. View, CA 94039-7311
This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:50:09 PDT