axmol/extensions/Particle3D/PU/PUOnVelocityObserver.cpp

/****************************************************************************
 Copyright (C) 2013 Henry van Merode. All rights reserved.
 Copyright (c) 2015-2016 Chukong Technologies Inc.
 Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

 https://axmolengine.github.io/

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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,
 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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#include "extensions/Particle3D/PU/PUOnVelocityObserver.h"
#include "extensions/Particle3D/PU/PUParticleSystem3D.h"

NS_AX_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 PUOnVelocityObserver::DEFAULT_VELOCITY_THRESHOLD = 0.0f;

//-----------------------------------------------------------------------
PUOnVelocityObserver::PUOnVelocityObserver()
    : PUObserver(), _threshold(DEFAULT_VELOCITY_THRESHOLD), _compare(CO_LESS_THAN){};
//-----------------------------------------------------------------------
bool PUOnVelocityObserver::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;
}

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

void PUOnVelocityObserver::copyAttributesTo(PUObserver* observer)
{
    PUObserver::copyAttributesTo(observer);

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

NS_AX_END