Martin Reddy (mxr++at++dcs.ed.ac.uk)
Tue, 21 Jan 1997 16:40:10 +0000 (GMT)
That depends on what you mean by updating objects. The principal work
which I am aware of on the subject is being done by Matthias Wloka at
Brown University as his doctoral topic (see refs below). In [2], Wloka
illustrates how Update Rates could be incorporated into contemporary
graphics systems, however I am not aware of any system that explicity
supports this concept (and he notes, 3 years ago, that no system existed
then). Most real-time graphics systems implicitly couple all objects'
update rate with the frame rate.
As I understand it, the notion of Update Rates is applicable to any
processing that you do in order to update the representation/state of an
object - i.e. it is not concerned with rendering of an object; which is
Performer's primary aim. You would have to implement any such processing
stages yourself, and so you would have to manage the update frequency of
that object yourself. Wloka mentions that the Inventor package offers
built-in support for Update Rates via its timer callbacks - these can be
used to update an object's attributes over time. Perhaps you could adopt a
similar approach under Performer, e.g. use a callback function which is
called each frame. Within that function you have a count of the number of
times it has been called (a local static counter). You then only perform
the processing if this counter, modulo the Update Rate, is zero.
Hope this helps,
Martin.
[1] M. M. Wloka (1993). "Thesis Proposal: Time-Critical Graphics".
Technical Report CS-93-50. Department of Computer Science, Brown
University, Providence, RI. (November)
ftp://ftp.cs.brown.edu/pub/techreports/93/cs93-50.ps.Z
[2] M. M. Wloka (1993). "Incorporating Update Rates into Today's Graphics
Systems". Technical Report CS-93-56. Department of Computer Science,
Brown University, Providence, RI. (December)
ftp://ftp.cs.brown.edu/pub/techreports/93/cs93-56.ps.Z
+============================================================================+
| Martin Reddy Dept. of Computer Science |
| University of Edinburgh |
| e-mail : M.Reddy++at++ed.ac.uk Mayfield Road, EH9 3JZ |
| http://www.dcs.ed.ac.uk/~mxr/ Tel : +44 131 650 5164 |
+============================================================================+
=======================================================================
List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
Submissions: info-performer++at++sgi.com
Admin. requests: info-performer-request++at++sgi.com
This archive was generated by hypermail 2.0b2 on Mon Aug 10 1998 - 17:54:24 PDT