Added SmokeTrailEffect which renders created particles as single quad or line

strip, in the case of the quad strip the strip is aligned to the be orthogonal with
the eye point.

include/osgParticle/ConstantRateCounter

@@ -0,0 +1,75 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2005 Robert Osfield 
+ *
+ * This library is open source and may be redistributed and/or modified under  
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+ * OpenSceneGraph Public License for more details.
+*/
+
+#ifndef OSGPARTICLE_CONSTANTRATECOUNTER
+#define OSGPARTICLE_CONSTANTRATECOUNTER 1
+
+#include <osgParticle/Counter>
+
+#include <osg/Object>
+#include <osg/Math>
+
+namespace osgParticle
+{
+
+    class ConstantRateCounter: public Counter {
+    public:
+        ConstantRateCounter():
+            Counter(), 
+            _minimumNumberOfParticlesToCreate(0),
+            _numberOfParticlesPerSecondToCreate(0)
+        {
+        }
+
+        ConstantRateCounter(const ConstantRateCounter& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY):
+             Counter(copy, copyop), 
+             _minimumNumberOfParticlesToCreate(copy._minimumNumberOfParticlesToCreate),
+             _numberOfParticlesPerSecondToCreate(copy._numberOfParticlesPerSecondToCreate)
+        {
+        }
+            
+        
+        META_Object(osgParticle, ConstantRateCounter);
+        
+        void setMinimumNumberOfParticlesToCreate(int minNumToCreate) { _minimumNumberOfParticlesToCreate = minNumToCreate; }
+        int getMinimumNumberOfParticlesToCreate() const { return _minimumNumberOfParticlesToCreate; }
+    
+        void setNumberOfParticlesPerSecondToCreate(double numPerSecond) { _numberOfParticlesPerSecondToCreate = numPerSecond; }
+        double getNumberOfParticlesPerSecondToCreate() const { return _numberOfParticlesPerSecondToCreate; }
+
+        /// Return the number of particles to be created in this frame
+        virtual int numParticlesToCreate(double dt) const
+        {
+            double v = (dt*_numberOfParticlesPerSecondToCreate);
+            int i = (int)(v);
+            _carryOver += (v-(double)i);
+            if (_carryOver>1.0)
+            {
+                ++i;
+                _carryOver -= 1.0;
+            }
+            return osg::maximum(_minimumNumberOfParticlesToCreate, i);
+        }
+        
+    protected:
+        virtual ~ConstantRateCounter() {}
+        
+        int _minimumNumberOfParticlesToCreate;
+        double _numberOfParticlesPerSecondToCreate;
+        mutable double _carryOver;
+    };
+    
+}
+
+
+#endif