95 lines
3.2 KiB
C++
95 lines
3.2 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2010 Robert Osfield
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*
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* This library is open source and may be redistributed and/or modified under
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* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
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* (at your option) any later version. The full license is in LICENSE file
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* included with this distribution, and on the openscenegraph.org website.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* OpenSceneGraph Public License for more details.
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*/
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// Written by Wang Rui, (C) 2010
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#ifndef OSGPARTICLE_DAMPINGOPERATOR
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#define OSGPARTICLE_DAMPINGOPERATOR
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#include <osgParticle/Operator>
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#include <osgParticle/Particle>
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namespace osgParticle
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{
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/** A damping operator applies damping constant to particle's velocity.
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Refer to David McAllister's Particle System API (http://www.particlesystems.org)
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*/
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class DampingOperator : public Operator
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{
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public:
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DampingOperator() : Operator(), _cutoffLow(0.0f), _cutoffHigh(FLT_MAX)
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{ _damping.set(1.0f, 1.0f, 1.0f); }
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DampingOperator( const DampingOperator& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY )
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: Operator(copy, copyop), _damping(copy._damping),
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_cutoffLow(copy._cutoffLow), _cutoffHigh(copy._cutoffHigh)
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{}
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META_Object( osgParticle, DampingOperator );
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/// Set the damping factors
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void setDamping( float x, float y, float z ) { _damping.set(x, y, z); }
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void setDamping( const osg::Vec3& damping ) { _damping = damping; }
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/// Set the damping factors to one value
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void setDamping( float x ) { _damping.set(x, x, x); }
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/// Get the damping factors
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void getDamping( float& x, float& y, float& z ) const
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{ x = _damping.x(); y = _damping.y(); z = _damping.z(); }
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const osg::Vec3& getDamping() const { return _damping; }
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/// Set the velocity cutoff factors
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void setCutoff( float low, float high ) { _cutoffLow = low; _cutoffHigh = high; }
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void setCutoffLow( float low ) { _cutoffLow = low; }
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void setCutoffHigh( float low ) { _cutoffHigh = low; }
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/// Get the velocity cutoff factors
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void getCutoff( float& low, float& high ) const { low = _cutoffLow; high = _cutoffHigh; }
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float getCutoffLow() const { return _cutoffLow; }
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float getCutoffHigh() const { return _cutoffHigh; }
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/// Apply the acceleration to a particle. Do not call this method manually.
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inline void operate( Particle* P, double dt );
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protected:
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virtual ~DampingOperator() {}
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DampingOperator& operator=( const DampingOperator& ) { return *this; }
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osg::Vec3 _damping;
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float _cutoffLow;
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float _cutoffHigh;
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};
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// INLINE METHODS
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inline void DampingOperator::operate( Particle* P, double dt )
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{
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const osg::Vec3& vel = P->getVelocity();
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float length2 = vel.length2();
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if ( length2>=_cutoffLow && length2<=_cutoffHigh )
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{
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osg::Vec3 newvel( vel.x() * (1.0f - (1.0f - _damping.x()) * dt),
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vel.y() * (1.0f - (1.0f - _damping.y()) * dt),
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vel.z() * (1.0f - (1.0f - _damping.z()) * dt) );
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P->setVelocity( newvel );
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}
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}
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}
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#endif
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