diff --git a/direct/src/particles/Particles.py b/direct/src/particles/Particles.py
index d89716cb02..f36df3bbd9 100644
--- a/direct/src/particles/Particles.py
+++ b/direct/src/particles/Particles.py
@@ -52,13 +52,13 @@ class Particles(ParticleSystem.ParticleSystem):
         self.setRenderParent(self.node)
         self.node.addPhysical(self)
 
-        self.factory = None 
+        self.factory = None
         self.factoryType = "undefined"
         self.setFactory("PointParticleFactory")
-        self.renderer = None 
+        self.renderer = None
         self.rendererType = "undefined"
         self.setRenderer("PointParticleRenderer")
-        self.emitter = None 
+        self.emitter = None
         self.emitterType = "undefined"
         self.setEmitter("SphereVolumeEmitter")
 
@@ -106,7 +106,7 @@ class Particles(ParticleSystem.ParticleSystem):
             self.factory = None
         self.factoryType = type
         if (type == "PointParticleFactory"):
-            self.factory = PointParticleFactory.PointParticleFactory() 
+            self.factory = PointParticleFactory.PointParticleFactory()
         elif (type == "ZSpinParticleFactory"):
             self.factory = ZSpinParticleFactory.ZSpinParticleFactory()
         elif (type == "OrientedParticleFactory"):
@@ -263,31 +263,40 @@ class Particles(ParticleSystem.ParticleSystem):
             file.write('# Z Spin factory parameters\n')
             file.write(targ + '.factory.setInitialAngle(%.4f)\n' % \
                                         self.factory.getInitialAngle())
-            file.write(targ + '.factory.setFinalAngle(%.4f)\n' % \
-                                        self.factory.getFinalAngle())
             file.write(targ + '.factory.setInitialAngleSpread(%.4f)\n' % \
                                         self.factory.getInitialAngleSpread())
-            file.write(targ + '.factory.setFinalAngleSpread(%.4f)\n' % \
+            file.write(targ + '.factory.enableAngularVelocity(%d)\n' % \
+                                        self.factory.getAngularVelocityEnabled())
+            if(self.factory.getAngularVelocityEnabled()):
+                file.write(targ + '.factory.setAngularVelocity(%.4f)\n' % \
+                                            self.factory.getAngularVelocity())
+                file.write(targ + '.factory.setAngularVelocitySpread(%.4f)\n' % \
+                                            self.factory.getAngularVelocitySpread())
+            else:
+                file.write(targ + '.factory.setFinalAngle(%.4f)\n' % \
+                                            self.factory.getFinalAngle())
+                file.write(targ + '.factory.setFinalAngleSpread(%.4f)\n' % \
                                         self.factory.getFinalAngleSpread())
+
         elif (self.factoryType == "OrientedParticleFactory"):
             file.write('# Oriented factory parameters\n')
             file.write(targ + '.factory.setInitialOrientation(%.4f)\n' % \
-                                        self.factory.getInitialOrientation()) 
+                                        self.factory.getInitialOrientation())
             file.write(targ + '.factory.setFinalOrientation(%.4f)\n' % \
                                         self.factory.getFinalOrientation())
 
         file.write('# Renderer parameters\n')
         alphaMode = self.renderer.getAlphaMode()
-        aMode = "PRALPHANONE" 
+        aMode = "PRALPHANONE"
         if (alphaMode == BaseParticleRenderer.BaseParticleRenderer.PRALPHANONE):
             aMode = "PRALPHANONE"
-        elif (alphaMode == 
+        elif (alphaMode ==
                 BaseParticleRenderer.BaseParticleRenderer.PRALPHAOUT):
             aMode = "PRALPHAOUT"
-        elif (alphaMode == 
+        elif (alphaMode ==
                 BaseParticleRenderer.BaseParticleRenderer.PRALPHAIN):
             aMode = "PRALPHAIN"
-        elif (alphaMode == 
+        elif (alphaMode ==
                 BaseParticleRenderer.BaseParticleRenderer.PRALPHAUSER):
             aMode = "PRALPHAUSER"
         file.write(targ + '.renderer.setAlphaMode(BaseParticleRenderer.' + aMode + ')\n')
@@ -298,9 +307,9 @@ class Particles(ParticleSystem.ParticleSystem):
             file.write(targ + '.renderer.setPointSize(%.2f)\n' % \
                                         self.renderer.getPointSize())
             sColor = self.renderer.getStartColor()
-            file.write((targ + '.renderer.setStartColor(Vec4(%.2f, %.2f, %.2f, %.2f))\n' % (sColor[0], sColor[1], sColor[2], sColor[3]))) 
+            file.write((targ + '.renderer.setStartColor(Vec4(%.2f, %.2f, %.2f, %.2f))\n' % (sColor[0], sColor[1], sColor[2], sColor[3])))
             sColor = self.renderer.getEndColor()
-            file.write((targ + '.renderer.setEndColor(Vec4(%.2f, %.2f, %.2f, %.2f))\n' % (sColor[0], sColor[1], sColor[2], sColor[3]))) 
+            file.write((targ + '.renderer.setEndColor(Vec4(%.2f, %.2f, %.2f, %.2f))\n' % (sColor[0], sColor[1], sColor[2], sColor[3])))
             blendType = self.renderer.getBlendType()
             bType = "PPONECOLOR"
             if (blendType == PointParticleRenderer.PointParticleRenderer.PPONECOLOR):
diff --git a/direct/src/tkpanels/ParticlePanel.py b/direct/src/tkpanels/ParticlePanel.py
index ec4ad24f64..a52686b340 100644
--- a/direct/src/tkpanels/ParticlePanel.py
+++ b/direct/src/tkpanels/ParticlePanel.py
@@ -214,7 +214,7 @@ class ParticlePanel(AppShell):
              0.0, None)
             )
         self.createFloaters(systemPage, systemFloaterDefs)
-        
+
         # Checkboxes
         self.createCheckbutton(
             systemPage, 'System', 'Render Space Velocities',
@@ -225,7 +225,7 @@ class ParticlePanel(AppShell):
             systemPage, 'System', 'System Grows Older',
             'On: system has a lifespan',
             self.toggleSystemGrowsOlder, 0)
-        
+
         # Vector widgets
         pos = self.createVector3Entry(systemPage, 'System', 'Pos',
                                       'Particle system position',
@@ -269,7 +269,8 @@ class ParticlePanel(AppShell):
             ('Factory', 'Terminal Vel. Spread',
              'Variation in terminal velocity',
              self.setFactoryTerminalVelocitySpread,
-             0.0, None))
+             0.0, None),
+        )
         self.createFloaters(factoryPage, factoryWidgets)
 
         self.factoryNotebook = Pmw.NoteBook(factoryPage, tabpos = None)
@@ -277,6 +278,23 @@ class ParticlePanel(AppShell):
         factoryPointPage = self.factoryNotebook.add('PointParticleFactory')
         # Z spin page #
         zSpinPage = self.factoryNotebook.add('ZSpinParticleFactory')
+
+        self.createCheckbutton(
+            zSpinPage, 'Z Spin Factory', 'Enable Angular Velocity',
+            ("On: angular velocity is used; " +
+             "Off: final angle is used"),
+            self.toggleAngularVelocity, 0, side = TOP),
+
+        self.createFloater(
+            zSpinPage, 'Z Spin Factory', 'Angular Velocity',
+             'How fast sprites rotate',
+             command = self.setFactoryZSpinAngularVelocity)
+
+        self.createFloater(
+            zSpinPage, 'Z Spin Factory', 'Angular Velocity Spread',
+             'Variation in how fast sprites rotate',
+             command = self.setFactoryZSpinAngularVelocitySpread)
+
         self.createAngleDial(zSpinPage, 'Z Spin Factory', 'Initial Angle',
                              'Starting angle in degrees',
                              fRollover = 1,
@@ -338,33 +356,33 @@ class ParticlePanel(AppShell):
             self.emissionType, BaseParticleEmitter.ETCUSTOM,
             self.setEmissionType)
         emissionFrame.pack(fill = 'x', expand = 0)
-        
+
         self.createFloater(
             emitterPage, 'Emitter', 'Velocity Multiplier',
             'launch velocity multiplier (all emission modes)',
             command = self.setEmitterAmplitude,
             min = None)
-        
+
         self.createFloater(
             emitterPage, 'Emitter', 'Velocity Multiplier Spread',
             'spread for launch velocity multiplier (all emission modes)',
             command = self.setEmitterAmplitudeSpread)
-        
+
         self.createVector3Entry(
             emitterPage, 'Emitter', 'Offset Velocity',
             'Velocity vector applied to all particles',
             command = self.setEmitterOffsetForce)
-        
+
         self.createVector3Entry(
             emitterPage, 'Emitter', 'Explicit Velocity',
             'all particles launch with this velocity in Explicit mode',
             command = self.setEmitterExplicitLaunchVector)
-        
+
         self.createVector3Entry(
             emitterPage, 'Emitter', 'Radiate Origin',
             'particles launch away from this point in Radiate mode',
             command = self.setEmitterRadiateOrigin)
-        
+
         self.emitterNotebook = Pmw.NoteBook(emitterPage, tabpos = None)
         # Box page #
         boxPage = self.emitterNotebook.add('BoxEmitter')
@@ -399,7 +417,7 @@ class ParticlePanel(AppShell):
             'On: magnitude/angle interpolation from center',
             self.toggleEmitterDiscCubicLerping, 0)
         customPage.pack(fill = BOTH, expand = 1)
-        
+
         # Line page #
         linePage = self.emitterNotebook.add('LineEmitter')
         self.createVector3Entry(linePage, 'Line Emitter', 'Min',
@@ -435,7 +453,7 @@ class ParticlePanel(AppShell):
                              'Particle launch angle',
                              command = self.setEmitterRingLaunchAngle)
         self.ringCustomFrame.pack(fill = BOTH, expand = 1)
-        
+
         # Sphere volume #
         sphereVolumePage = self.emitterNotebook.add('SphereVolumeEmitter')
         self.createFloater(sphereVolumePage, 'Sphere Volume Emitter', 'Radius',
@@ -449,7 +467,7 @@ class ParticlePanel(AppShell):
                            'Radius of sphere',
                            command = self.setEmitterSphereSurfaceRadius,
                            min = 0.01)
-        # Tangent ring # 
+        # Tangent ring #
         tangentRingPage = self.emitterNotebook.add('TangentRingEmitter')
         self.createFloater(tangentRingPage, 'Tangent Ring Emitter', 'Radius',
                            'Radius of ring',
@@ -471,12 +489,12 @@ class ParticlePanel(AppShell):
                               "alpha setting over particles' lifetime",
                               ('NO_ALPHA','ALPHA_OUT','ALPHA_IN','ALPHA_USER'),
                               self.setRendererAlphaMode)
-        
+
         self.createSlider(
             rendererPage, 'Renderer', 'User Alpha',
             'alpha value for ALPHA_USER alpha mode',
             command = self.setRendererUserAlpha)
-        
+
         self.rendererNotebook = Pmw.NoteBook(rendererPage, tabpos = None)
         # Line page #
         linePage = self.rendererNotebook.add('LineParticleRenderer')
@@ -666,7 +684,7 @@ class ParticlePanel(AppShell):
         # This also has: setCoef, setLength, setRadius,
         forceMenu.add_command(label = 'Add Linear Cylinder Vortex Force',
                             command = self.addLinearCylinderVortexForce)
-        
+
         # DERIVED FROM LINEAR DISTANCE FORCE
         # Parameters: setFalloffType, setForceCenter, setRadius
         forceMenu.add_command(label = 'Add Linear Sink Force',
@@ -688,14 +706,14 @@ class ParticlePanel(AppShell):
         # Notebook to hold force widgets as the are added
         self.forceGroupNotebook = Pmw.NoteBook(self.forceFrame, tabpos = None)
         self.forceGroupNotebook.pack(fill = X)
-        
+
         self.factoryNotebook.setnaturalsize()
         self.emitterNotebook.setnaturalsize()
         self.rendererNotebook.setnaturalsize()
         self.forceGroupNotebook.setnaturalsize()
         self.mainNotebook.setnaturalsize()
-        
-        # Make sure input variables processed 
+
+        # Make sure input variables processed
         self.initialiseoptions(ParticlePanel)
 
     ### WIDGET UTILITY FUNCTIONS ###
@@ -712,7 +730,7 @@ class ParticlePanel(AppShell):
         self.widgetDict[category + '-' + text] = widget
         self.variableDict[category + '-' + text] = bool
         return widget
-        
+
     def createRadiobutton(self, parent, side, category, text,
                           balloonHelp, variable, value,
                           command):
@@ -724,7 +742,7 @@ class ParticlePanel(AppShell):
         self.bind(widget, balloonHelp)
         self.widgetDict[category + '-' + text] = widget
         return widget
-        
+
     def createFloaters(self, parent, widgetDefinitions):
         widgets = []
         for category, label, balloonHelp, command, min, resolution in widgetDefinitions:
@@ -864,7 +882,7 @@ class ParticlePanel(AppShell):
             self.forceGroupLabel['text'] = self.forceGroup.getName()
         else:
             self.forceGroupLabel['text'] = 'Force Group'
-    
+
     def updateMenus(self):
         self.updateEffectsMenus()
         self.updateParticlesMenus()
@@ -878,7 +896,7 @@ class ParticlePanel(AppShell):
         # Add in a checkbutton for each effect (to toggle on/off)
         keys = self.effectsDict.keys()
         keys.sort()
-        for name in keys: 
+        for name in keys:
             effect = self.effectsDict[name]
             self.effectsLabelMenu.add_command(
                 label = effect.getName(),
@@ -966,7 +984,7 @@ class ParticlePanel(AppShell):
             effect.enable()
         else:
             effect.disable()
-        
+
     def selectParticlesNamed(self, name):
         particles = self.particleEffect.getParticlesNamed(name)
         if particles != None:
@@ -997,13 +1015,13 @@ class ParticlePanel(AppShell):
             force.setActive(1)
         else:
             force.setActive(0)
-                    
+
     def getWidget(self, category, text):
         return self.widgetDict[category + '-' + text]
 
     def getVariable(self, category, text):
         return self.variableDict[category + '-' + text]
-    
+
     def loadParticleEffectFromFile(self):
         # Find path to particle directory
         pPath = getParticlePath()
@@ -1083,7 +1101,7 @@ class ParticlePanel(AppShell):
             self.particleEffect.enable()
         else:
             self.particleEffect.disable()
-            
+
     ## SYSTEM PAGE ##
     def updateSystemWidgets(self):
         poolSize = self.particles.getPoolSize()
@@ -1133,7 +1151,7 @@ class ParticlePanel(AppShell):
 
     def selectFactoryPage(self):
         pass
-        
+
     def updateFactoryWidgets(self):
         factory = self.particles.factory
         lifespan = factory.getLifespanBase()
@@ -1149,7 +1167,7 @@ class ParticlePanel(AppShell):
         terminalVelocitySpread = factory.getTerminalVelocitySpread()
         self.getWidget('Factory', 'Terminal Vel. Spread').set(
             terminalVelocitySpread, 0)
-        
+
     def setFactoryLifeSpan(self, value):
         self.particles.factory.setLifespanBase(value)
     def setFactoryLifeSpanSpread(self, value):
@@ -1172,6 +1190,10 @@ class ParticlePanel(AppShell):
         self.particles.factory.setFinalAngle(angle)
     def setFactoryZSpinFinalAngleSpread(self, spread):
         self.particles.factory.setFinalAngleSpread(spread)
+    def setFactoryZSpinAngularVelocity(self, vel):
+        self.particles.factory.setAngularVelocity(vel)
+    def setFactoryZSpinAngularVelocitySpread(self, spread):
+        self.particles.factory.setAngularVelocitySpread(spread)
 
     ## EMITTER PAGE ##
     def selectEmitterType(self, type):
@@ -1183,7 +1205,7 @@ class ParticlePanel(AppShell):
         type = self.particles.emitter.__class__.__name__
         self.emitterNotebook.selectpage(type)
         self.getVariable('Emitter', 'Emitter Type').set(type)
-        
+
     def updateEmitterWidgets(self):
         emitter = self.particles.emitter
         self.setEmissionType(self.particles.emitter.getEmissionType())
@@ -1371,7 +1393,7 @@ class ParticlePanel(AppShell):
         self.rendererNotebook.selectpage(type)
         self.particles.setRenderer(type)
         self.updateRendererWidgets()
-        
+
     def updateRendererWidgets(self):
         renderer = self.particles.renderer
         alphaMode = renderer.getAlphaMode()
@@ -1571,8 +1593,8 @@ class ParticlePanel(AppShell):
             self.rendererSpriteFileEntry['state'] = 'disabled'
             self.rendererSpriteNodeEntry['state'] = 'disabled'
             self.rendererSpriteTextureEntry['background'] = 'SystemWindow'
-            self.rendererSpriteFileEntry['background'] = '#C0C0C0'            
-            self.rendererSpriteNodeEntry['background'] = '#C0C0C0'            
+            self.rendererSpriteFileEntry['background'] = '#C0C0C0'
+            self.rendererSpriteNodeEntry['background'] = '#C0C0C0'
         else:
             self.rendererSpriteTextureEntry['state'] = 'disabled'
             self.rendererSpriteFileEntry['state'] = 'normal'
@@ -1599,6 +1621,11 @@ class ParticlePanel(AppShell):
     def toggleRendererSpriteAnimAngle(self):
         self.particles.renderer.setAnimAngleFlag(
             self.getVariable('Sprite Renderer', 'Anim Angle').get())
+
+    def toggleAngularVelocity(self):
+        self.particles.factory.enableAngularVelocity(
+            self.getVariable('Z Spin Factory', 'Enable Angular Velocity').get())
+
     def setRendererSpriteInitialXScale(self, xScale):
         self.particles.renderer.setInitialXScale(xScale)
     def setRendererSpriteFinalXScale(self, xScale):
@@ -1623,7 +1650,7 @@ class ParticlePanel(AppShell):
     def toggleRendererSpriteAlphaDisable(self):
         self.particles.renderer.setAlphaDisable(
             self.getVariable('Sprite Renderer', 'Alpha Disable').get())
-        
+
     ## FORCEGROUP COMMANDS ##
     def updateForceWidgets(self):
         # Select appropriate notebook page
diff --git a/panda/src/particlesystem/zSpinParticle.I b/panda/src/particlesystem/zSpinParticle.I
index 77c72bb46d..0fd6d9fa7d 100644
--- a/panda/src/particlesystem/zSpinParticle.I
+++ b/panda/src/particlesystem/zSpinParticle.I
@@ -51,3 +51,25 @@ INLINE float ZSpinParticle::
 get_final_angle(void) const {
   return _final_angle;
 }
+
+INLINE float ZSpinParticle::
+get_angular_velocity(void) const {
+  return _angular_velocity;
+}
+
+INLINE void ZSpinParticle::
+set_angular_velocity(float v) {
+  _angular_velocity = v;
+}
+
+INLINE void ZSpinParticle::
+enable_angular_velocity(bool bEnabled) {
+  _bUseAngularVelocity = bEnabled;
+}
+
+INLINE bool ZSpinParticle::
+get_angular_velocity_enabled(void) const {
+  return _bUseAngularVelocity;
+}
+
+
diff --git a/panda/src/particlesystem/zSpinParticle.cxx b/panda/src/particlesystem/zSpinParticle.cxx
index b06e952c18..5af8f577ad 100644
--- a/panda/src/particlesystem/zSpinParticle.cxx
+++ b/panda/src/particlesystem/zSpinParticle.cxx
@@ -29,6 +29,8 @@ ZSpinParticle(void) :
   _initial_angle = 0.0f;
   _final_angle = 0.0f;
   _cur_angle = 0.0f;
+  _angular_velocity = 0.0f;
+  _bUseAngularVelocity = false;
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -42,6 +44,8 @@ ZSpinParticle(const ZSpinParticle &copy) :
   _initial_angle = copy._initial_angle;
   _final_angle = copy._final_angle;
   _cur_angle = copy._cur_angle;
+  _angular_velocity = copy._angular_velocity;
+  _bUseAngularVelocity = copy._bUseAngularVelocity;
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -79,17 +83,23 @@ init(void) {
 ////////////////////////////////////////////////////////////////////
 void ZSpinParticle::
 update(void) {
-  float t = get_parameterized_age();
+  // if using final_angle, want age to range from [0,1] over lifespan, so use parameterized_age
+  // for angular velocity, should be allowed to range freely upward, use regular age
 
-  // interpolate the current orientation
-  _cur_angle = _initial_angle + (t * (_final_angle - _initial_angle));
+  if(_bUseAngularVelocity) {
+   // interpolate the current orientation
+      _cur_angle = _initial_angle + (get_age() * _angular_velocity);
+  } else {
+      _cur_angle = _initial_angle + (get_parameterized_age() * (_final_angle - _initial_angle));
+  }
 
   // normalize the result to [0..360)
   _cur_angle = fmod(_cur_angle, 360.0f);
 
   // if _cur_angle was negative, it is still negative after fmod,
-  // but greater than -360.
   // wrap it around by adding 360
+
+  // is this really necessary?  should be in range of sin/cos
   if(_cur_angle < 0.0f)
     _cur_angle += 360.0f;
 }
diff --git a/panda/src/particlesystem/zSpinParticle.h b/panda/src/particlesystem/zSpinParticle.h
index 414c34a68b..f29c0aae8f 100644
--- a/panda/src/particlesystem/zSpinParticle.h
+++ b/panda/src/particlesystem/zSpinParticle.h
@@ -34,6 +34,8 @@ private:
   float _initial_angle;
   float _final_angle;
   float _cur_angle;
+  float _angular_velocity;
+  bool  _bUseAngularVelocity;
 
 public:
   ZSpinParticle(void);
@@ -53,6 +55,14 @@ public:
 
   INLINE void set_final_angle(float t);
   INLINE float get_final_angle(void) const;
+
+  // 'set_final_angle' and 'angular_velocity' are mutually exclusive apis
+  // if angular-velocity is specified, final_angle is ignored
+  INLINE void  set_angular_velocity(float v);
+  INLINE float get_angular_velocity(void) const;
+
+  INLINE void enable_angular_velocity(bool bEnabled);
+  INLINE bool get_angular_velocity_enabled(void) const;
 };
 
 #include "zSpinParticle.I"
diff --git a/panda/src/particlesystem/zSpinParticleFactory.I b/panda/src/particlesystem/zSpinParticleFactory.I
index ef415553ba..b3e44c9589 100644
--- a/panda/src/particlesystem/zSpinParticleFactory.I
+++ b/panda/src/particlesystem/zSpinParticleFactory.I
@@ -88,3 +88,39 @@ INLINE float ZSpinParticleFactory::
 get_final_angle_spread(void) const {
   return _final_angle_spread;
 }
+
+////////////////////////////////////////////////////////////////////
+// Function : get_angular_velocity
+//   Access : public
+////////////////////////////////////////////////////////////////////
+INLINE float ZSpinParticleFactory::
+get_angular_velocity(void) const {
+  return _angular_velocity;
+}
+
+INLINE void ZSpinParticleFactory::
+set_angular_velocity(float v) {
+  _angular_velocity = v;
+}
+
+INLINE float ZSpinParticleFactory::
+get_angular_velocity_spread(void) const {
+  return _angular_velocity_spread;
+}
+
+INLINE void ZSpinParticleFactory::
+set_angular_velocity_spread(float spread) {
+  _angular_velocity_spread = spread;
+}
+
+
+INLINE void ZSpinParticleFactory::
+enable_angular_velocity(bool bEnabled) {
+  _bUseAngularVelocity = bEnabled;
+}
+
+INLINE bool ZSpinParticleFactory::
+get_angular_velocity_enabled(void) const {
+  return _bUseAngularVelocity;
+}
+
diff --git a/panda/src/particlesystem/zSpinParticleFactory.cxx b/panda/src/particlesystem/zSpinParticleFactory.cxx
index d6de0aaa23..61f7d5988d 100644
--- a/panda/src/particlesystem/zSpinParticleFactory.cxx
+++ b/panda/src/particlesystem/zSpinParticleFactory.cxx
@@ -31,6 +31,9 @@ ZSpinParticleFactory(void) :
   _final_angle = 0.0f;
   _initial_angle_spread = 0.0f;
   _final_angle_spread = 0.0f;
+  _angular_velocity = 0.0f;
+  _angular_velocity_spread = 0.0f;
+  _bUseAngularVelocity = false;
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -45,6 +48,9 @@ ZSpinParticleFactory(const ZSpinParticleFactory &copy) :
   _final_angle = copy._final_angle;
   _initial_angle_spread = copy._initial_angle_spread;
   _final_angle_spread = copy._final_angle_spread;
+  _angular_velocity = copy._angular_velocity;
+  _angular_velocity_spread = copy._angular_velocity_spread;
+  _bUseAngularVelocity = copy._bUseAngularVelocity;
 }
 
 ////////////////////////////////////////////////////////////////////
@@ -77,4 +83,6 @@ populate_child_particle(BaseParticle *bp) const {
 
   zsp->set_initial_angle(_initial_angle + SPREAD(_initial_angle_spread));
   zsp->set_final_angle(_final_angle + SPREAD(_final_angle_spread));
+  zsp->set_angular_velocity(_angular_velocity + SPREAD(_angular_velocity_spread));
+  zsp->enable_angular_velocity(_bUseAngularVelocity);
 }
diff --git a/panda/src/particlesystem/zSpinParticleFactory.h b/panda/src/particlesystem/zSpinParticleFactory.h
index 73b4cb660f..5ae43089c0 100644
--- a/panda/src/particlesystem/zSpinParticleFactory.h
+++ b/panda/src/particlesystem/zSpinParticleFactory.h
@@ -31,10 +31,11 @@ private:
   virtual void populate_child_particle(BaseParticle *bp) const;
   virtual BaseParticle *alloc_particle(void) const;
 
-  float _initial_angle;
-  float _final_angle;
-  float _initial_angle_spread;
-  float _final_angle_spread;
+  float _initial_angle,_initial_angle_spread;
+  float _final_angle,_final_angle_spread;
+  float _angular_velocity,_angular_velocity_spread;
+  bool  _bUseAngularVelocity;
+
 
 PUBLISHED:
   ZSpinParticleFactory(void);
@@ -50,6 +51,15 @@ PUBLISHED:
   INLINE float get_final_angle(void) const;
   INLINE float get_initial_angle_spread(void) const;
   INLINE float get_final_angle_spread(void) const;
+
+  INLINE void  set_angular_velocity(float v);
+  INLINE float get_angular_velocity(void) const;
+
+  INLINE void  set_angular_velocity_spread(float spread);
+  INLINE float get_angular_velocity_spread(void) const;
+
+  INLINE void enable_angular_velocity(bool bEnabled);
+  INLINE bool get_angular_velocity_enabled(void) const;
 };
 
 #include "zSpinParticleFactory.I"