Angus Dorbie (angus++at++division.co.uk)
Wed, 10 May 1995 11:50:24 +0100
Although I've not applied the techniques specifically to terrain, I
have found it really simple to implement dynamic geometry in geosets.
Basically, the coordinate & other information is held in memory and you
are free to write new values for your vertex information to memory.
One important choice is what type of geoset you decide to use. If you use
indexed geosets then typically each vertex is represented once in a neat
list with connectivity information held in an index list. This reduces
the bandwidth required to update vertices and makes for a neater
implementation. Non indexed geosets can be slightly faster to draw
but typically hold multiple copies of each vertex making it trickier to
update an individual vertex.
Changing connectivity is a different kettle of fish and I've never needed
to try this, clearly indexed geosets have further advantages for this type
of dynamic update.
There's a cute SigGraph 93 paper "Modeling Soil: Realtime Dynamic Models
for Soil Slippage and Manipulation" . I noticed that Lance Marrou got an
acknowledgement at the end (he mails the group). Maybe he has aquired some
'soil specific' experience with performer.
-- Angus Dorbie Division Ltd, Software Engineer 19 Apex Court, Tel: (01454)615554 Woodlands, Fax: (01454)615532 Bristol BS12 4JT, angus++at++division.co.uk UK
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