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.

src/osgParticle/Particle.cpp

@@ -1,5 +1,6 @@
 #include <osgParticle/Particle>
 #include <osgParticle/LinearInterpolator>
+#include <osgParticle/ParticleSystem>
 
 #include <osg/Vec3>
 #include <osg/Vec4>
@@ -48,8 +49,8 @@ osgParticle::Particle::Particle()
     _cur_tile(-1),
     _s_coord(0.0f),
     _t_coord(0.0f),
-    _previousParticle(0),
-    _nextParticle(0)
+    _previousParticle(INVALID_INDEX),
+    _nextParticle(INVALID_INDEX)
 {
 }
 
@@ -81,10 +82,14 @@ bool osgParticle::Particle::update(double dt)
     int currentTile = static_cast<int>(x * _num_tile);
     
     //If the current texture tile is different from previous, then compute new texture coords
-    if(currentTile != _cur_tile) {
+    if(currentTile != _cur_tile)
+    {
+    
         _cur_tile = currentTile;
         _s_coord = _s_tile * fmod(_cur_tile , 1.0 / _s_tile);
         _t_coord = 1.0 - _t_tile * (static_cast<int>(_cur_tile * _t_tile) + 1);
+
+        // osg::notify(osg::NOTICE)<<this<<" setting tex coords "<<_s_coord<<" "<<_t_coord<<std::endl;
     }
     
     // compute the current values for size, alpha and color.
@@ -215,3 +220,23 @@ void osgParticle::Particle::render(const osg::Vec3& xpos, const osg::Vec3& px, c
         osg::notify(osg::WARN) << "Invalid shape for particles\n";
     }
 }
+
+void osgParticle::Particle::setUpTexCoordsAsPartOfConnectedParticleSystem(ParticleSystem* ps)
+{
+    if (getPreviousParticle()!=Particle::INVALID_INDEX)
+    {
+        update(0.0);
+
+        Particle* previousParticle = ps->getParticle(getPreviousParticle());
+        const osg::Vec3& previousPosition = previousParticle->getPosition();
+        const osg::Vec3& newPosition = getPosition();
+        float distance = (newPosition-previousPosition).length();
+        float s_coord_delta = 0.5f*distance/getCurrentSize();
+        float s_coord = previousParticle->_s_coord + s_coord_delta;
+
+        setTextureTile(0,0,0);
+        _cur_tile = 0;
+        _s_coord = s_coord;
+        _t_coord = 0.0f;
+    }
+}