axmol/extensions/Particle3D/ParticleUniverse/ParticleObservers/CCPUParticle3DOnVelocityObserver.cpp

/****************************************************************************
 Copyright (C) 2013 Henry van Merode. All rights reserved.
 Copyright (c) 2015 Chukong Technologies Inc.
 
 http://www.cocos2d-x.org
 
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 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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#include "extensions/Particle3D/ParticleUniverse/ParticleObservers/CCPUParticle3DOnVelocityObserver.h"
#include "extensions/Particle3D/ParticleUniverse/CCPUParticleSystem3D.h"

NS_CC_BEGIN

static bool almostEquals(float a, float b, float epsilon = std::numeric_limits<float>::epsilon())
{
    return fabs(a - b) <= ( (fabs(a) < fabs(b) ? fabs(b) : fabs(a)) * epsilon); 
};

// Constants
const float PUParticle3DOnVelocityObserver::DEFAULT_VELOCITY_THRESHOLD = 0.0f;

//-----------------------------------------------------------------------
PUParticle3DOnVelocityObserver::PUParticle3DOnVelocityObserver(void) : 
    PUParticle3DObserver(),
    _threshold(DEFAULT_VELOCITY_THRESHOLD),
    _compare(CO_LESS_THAN)
{
};
//-----------------------------------------------------------------------
bool PUParticle3DOnVelocityObserver::observe (PUParticle3D* particle, float timeElapsed)
{
    if (!particle)
        return false;

    // Compensate for the scaled velocity
    float scaleVelocity = _particleSystem->getParticleSystemScaleVelocity();
    if (_compare == CO_GREATER_THAN)
    {
        // Changed in V 1.3.1
        return (particle->calculateVelocity()) > (scaleVelocity * _threshold);
    }
    else if (_compare == CO_LESS_THAN)
    {
        return (particle->calculateVelocity()) < (scaleVelocity * _threshold);
    }
    else
    {
        // Equals
        return almostEquals(particle->calculateVelocity(), (scaleVelocity * _threshold), 0.01f);
    }

    return false;
}

PUParticle3DOnVelocityObserver* PUParticle3DOnVelocityObserver::create()
{
    auto pvo = new (std::nothrow) PUParticle3DOnVelocityObserver();
    pvo->autorelease();
    return pvo;
}

void PUParticle3DOnVelocityObserver::copyAttributesTo( PUParticle3DObserver* observer )
{
    PUParticle3DObserver::copyAttributesTo(observer);

    PUParticle3DOnVelocityObserver* onVelocityObserver = static_cast<PUParticle3DOnVelocityObserver*>(observer);
    onVelocityObserver->_threshold = _threshold;
    onVelocityObserver->_compare = _compare;
}

NS_CC_END