128 lines
3.9 KiB
C++
128 lines
3.9 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_EXPLOSIONOPERATOR
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#define OSGPARTICLE_EXPLOSIONOPERATOR
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#include <osgParticle/ModularProgram>
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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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/** An explosion operator exerts force on each particle away from the explosion center.
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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 ExplosionOperator : public Operator
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{
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public:
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ExplosionOperator()
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: Operator(), _radius(1.0f),
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_magnitude(1.0f), _epsilon(1e-3), _sigma(1.0f),
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_inexp(0.0f), _outexp(0.0f)
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{}
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ExplosionOperator( const ExplosionOperator& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY )
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: Operator(copy, copyop), _center(copy._center), _radius(copy._radius),
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_magnitude(copy._magnitude), _epsilon(copy._epsilon), _sigma(copy._sigma),
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_inexp(copy._inexp), _outexp(copy._outexp)
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{}
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META_Object( osgParticle, ExplosionOperator );
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/// Set the center of shock wave
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void setCenter( const osg::Vec3& c ) { _center = c; }
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/// Get the center of shock wave
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const osg::Vec3& getCenter() const { return _center; }
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/// Set the radius of wave peak
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void setRadius( float r ) { _radius = r; }
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/// Get the radius of wave peak
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float getRadius() const { return _radius; }
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/// Set the acceleration scale
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void setMagnitude( float mag ) { _magnitude = mag; }
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/// Get the acceleration scale
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float getMagnitude() const { return _magnitude; }
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/// Set the acceleration epsilon
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void setEpsilon( float eps ) { _epsilon = eps; }
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/// Get the acceleration epsilon
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float getEpsilon() const { return _epsilon; }
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/// Set broadness of the strength of the wave
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void setSigma( float s ) { _sigma = s; }
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/// Get broadness of the strength of the wave
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float getSigma() const { return _sigma; }
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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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/// Perform some initializations. Do not call this method manually.
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inline void beginOperate( Program* prg );
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protected:
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virtual ~ExplosionOperator() {}
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ExplosionOperator& operator=( const ExplosionOperator& ) { return *this; }
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osg::Vec3 _center;
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osg::Vec3 _xf_center;
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float _radius;
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float _magnitude;
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float _epsilon;
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float _sigma;
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float _inexp;
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float _outexp;
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};
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// INLINE METHODS
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inline void ExplosionOperator::operate( Particle* P, double dt )
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{
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osg::Vec3 dir = P->getPosition() - _xf_center;
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float length = dir.length();
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float distanceFromWave2 = (_radius - length) * (_radius - length);
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float Gd = exp(distanceFromWave2 * _inexp) * _outexp;
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float factor = (_magnitude * dt) / (length * (_epsilon+length*length));
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P->addVelocity( dir * (Gd * factor) );
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}
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inline void ExplosionOperator::beginOperate( Program* prg )
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{
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if ( prg->getReferenceFrame()==ModularProgram::RELATIVE_RF )
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{
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_xf_center = prg->transformLocalToWorld(_center);
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}
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else
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{
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_xf_center = _center;
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}
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float oneOverSigma = (_sigma!=0.0f ? (1.0f / _sigma) : 1.0f);
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_inexp = -0.5f * oneOverSigma * oneOverSigma;
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_outexp = oneOverSigma / sqrt(osg::PI * 2.0f);
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}
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}
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#endif
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