From Farshid Lashkari, "I noticed that sometimes when a particle emitter is re-enabled, a few

particles will appear at the location it was disabled at. The problem
is that the previous local to world matrix is not being updated while
it is disabled. I modified the particle processor so that it will set
the dirty flag for the previous local to world matrix when the
processor is skipped for a frame, since the value will no longer be
relevant."

src/osgParticle/ParticleProcessor.cpp

@@ -108,6 +108,11 @@ void osgParticle::ParticleProcessor::traverse(osg::NodeVisitor& nv)
 
                             // do some process (unimplemented in this base class)
                             process(t - _t0);
+                        } else {
+                            //The values of _previous_wtl_matrix and _previous_ltw_matrix will be invalid
+                            //since processing was skipped for this frame
+                            _first_ltw_compute = true;
+                            _first_wtl_compute = true;
                         }
                     }