77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 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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//osgParticle - Copyright (C) 2002 Marco Jez
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#ifndef OSGPARTICLE_RANDOMRATE_COUNTER
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#define OSGPARTICLE_RANDOMRATE_COUNTER 1
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#include <osgParticle/VariableRateCounter>
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#include <osg/CopyOp>
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#include <osg/Object>
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namespace osgParticle
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{
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class RandomRateCounter: public VariableRateCounter {
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public:
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inline RandomRateCounter();
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inline RandomRateCounter(const RandomRateCounter& copy, const osg::CopyOp& copyop = osg::CopyOp::SHALLOW_COPY);
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META_Object(osgParticle, RandomRateCounter);
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/// Return the number of particles to be created in this frame
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inline int numParticlesToCreate(double dt) const;
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protected:
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virtual ~RandomRateCounter() {}
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mutable float _np;
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};
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// INLINE FUNCTIONS
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inline RandomRateCounter::RandomRateCounter()
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: VariableRateCounter(), _np(0)
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{
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}
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inline RandomRateCounter::RandomRateCounter(const RandomRateCounter& copy, const osg::CopyOp& copyop)
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: VariableRateCounter(copy, copyop), _np(copy._np)
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{
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}
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inline int RandomRateCounter::numParticlesToCreate(double dt) const
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{
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// compute the number of new particles, clamping it to 1 second of particles at the maximum rate
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float numNewParticles = osg::minimum(static_cast<float>(dt * getRateRange().get_random()), getRateRange().maximum);
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// add the number of new particles to value carried over from the previous call
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_np += numNewParticles;
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// round down the number of particles.
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int n = static_cast<int>(_np);
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// take away the number of rounded number of particles leaving the decimal place
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// this is done so that two frames of 0.5's will results in first frame 0 new particles, second frame 1
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_np -= n;
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// return the rounded number of particles to be created
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return n;
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}
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}
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#endif
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