Checked in osgParticle, writtten by Marco Jez.

include/osgParticle/FluidFrictionOperator

@@ -0,0 +1,132 @@
+//C++ header - Open Scene Graph - Copyright (C) 1998-2002 Robert Osfield
+//Distributed under the terms of the GNU Library General Public License (LGPL)
+//as published by the Free Software Foundation.
+//osgParticle - Copyright (C) 2002 Marco Jez
+
+#ifndef OSGPARTICLE_FLUIDFRICTIONOPERATOR_
+#define OSGPARTICLE_FLUIDFRICTIONOPERATOR_ 1
+
+#include <osgParticle/Export>
+#include <osgParticle/Operator>
+
+#include <osg/CopyOp>
+#include <osg/Object>
+#include <osg/Math>
+
+namespace osgParticle
+{
+
+    class Particle;    
+
+    /**    An operator that simulates the friction of a fluid.
+        By using this operator you can let the particles move in a fluid of a given <I>density</I>
+        and <I>viscosity</I>. There are two functions to quickly setup the parameters for pure water
+        and air. You can decide whether to compute the forces using the particle's physical 
+        radius or another value, by calling the <CODE>setOverrideRadius()</CODE> method.
+    */
+    class OSGPARTICLE_EXPORT FluidFrictionOperator: public Operator {
+    public:
+        
+        FluidFrictionOperator();
+        FluidFrictionOperator(const FluidFrictionOperator &copy, const osg::CopyOp &copyop = osg::CopyOp::SHALLOW_COPY);
+        
+        META_Object(FluidFrictionOperator);
+        
+        /// Get the density of the fluid.
+        inline float getFluidDensity() const;
+        
+        /// Set the density of the fluid.
+        inline void setFluidDensity(float d);
+        
+        /// Get the viscosity of the fluid.
+        inline float getFluidViscosity() const;
+        
+        /// Set the viscosity of the fluid.
+        inline void setFluidViscosity(float v);
+        
+        /// Get the overriden radius value.
+        inline float getOverrideRadius() const;        
+        
+        /// Set the overriden radius value (pass 0 if you want to use particle's radius).
+        inline void setOverrideRadius(float r);
+        
+        /// Set the fluid parameters as for air (20<32>C temperature).
+        inline void setFluidToAir();
+        
+        /// Set the fluid parameters as for pure water (20<32>C temperature).
+        inline void setFluidToWater();
+        
+        /// Apply the friction forces to a particle. Do not call this method manually.
+        void operate(Particle *P, double dt);
+        
+        /// Perform some initializations. Do not call this method manually.
+        inline void beginOperate(Program *prg);
+        
+    protected:
+        virtual ~FluidFrictionOperator() {}
+        FluidFrictionOperator &operator=(const FluidFrictionOperator &) { return *this; }
+        
+    private:
+        float A_;
+        float B_;
+        float density_;
+        float viscosity_;
+        float ovr_rad_;
+        Program *current_program_;
+    };
+    
+    // INLINE FUNCTIONS
+    
+    inline float FluidFrictionOperator::getFluidDensity() const
+    {
+        return density_;
+    }
+
+    inline float FluidFrictionOperator::getFluidViscosity() const
+    {
+        return viscosity_;
+    }
+    
+    inline void FluidFrictionOperator::setFluidDensity(float d)
+    {
+        density_ = d;
+        B_ = 0.2f * osg::PI * density_;
+    }
+
+    inline void FluidFrictionOperator::setFluidViscosity(float v)
+    {
+        viscosity_ = v;
+        A_ = 6 * osg::PI * viscosity_;
+    }
+    
+    inline void FluidFrictionOperator::setFluidToAir()
+    {
+        setFluidViscosity(1.8e-5f);
+        setFluidDensity(1.2929f);
+    }
+
+    inline void FluidFrictionOperator::setFluidToWater()
+    {
+        setFluidViscosity(1.002e-3f);
+        setFluidDensity(1.0f);
+    }
+    
+    inline float FluidFrictionOperator::getOverrideRadius() const
+    {
+        return ovr_rad_;
+    }
+    
+    inline void FluidFrictionOperator::setOverrideRadius(float r)
+    {
+        ovr_rad_ = r;
+    }
+    
+    inline void FluidFrictionOperator::beginOperate(Program *prg)
+    {
+        current_program_ = prg;
+    }
+
+}
+
+
+#endif