pumpkin wrote:
I need behavior what is triggered if 2 of the same kind hit eachother. So a
shape from BranchGroup 1 + a shape from branchgroup 2 => no collision, no
behavior triggered. Two from group X => collision, behavior triggered.
Ah... what you are seeking is not a picking system at all, but the
n-body collision detection. This is, mathematically speaking, quite a
frightening subject to deal with. A trivial implementation is O(n^2)
computation. If you start making approximations and some assumption
about object shapes, you can get this down to almost linear, depending
on the algorithm and degree of precision needed.
I got about 90% of the way through an implementation of Kelvin Chung's
HS-Jump/Q-Collide algorithms late last year but never got them finished.
I believe I put the code into the j3d.org repository, but not definite
on that. These work with non-convex object shapes and are reasonably
efficient depending on your object shape (HS_Jump is more efficient for
long, thin cylinders, Q-Collide for spherical). If you have non-convex
objects then there are several different options out there to play
with, but they are non-trivial to implement.
--
Justin Couch http://www.vlc.com.au/~justin/
Java Architect & Bit Twiddler http://www.yumetech.com/
Author, Java 3D FAQ Maintainer http://www.j3d.org/
-------------------------------------------------------------------
"Look through the lens, and the light breaks down into many lights.
Turn it or move it, and a new set of arrangements appears... is it
a single light or many lights, lights that one must know how to
distinguish, recognise and appreciate? Is it one light with many
frames or one frame for many lights?" -Subcomandante Marcos
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