India/cocos2d-x/extensions/Particle3D/PU/CCPUSphere.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.
 
 http://www.cocos2d-x.org
 
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 of this software and associated documentation files (the "Software"), to deal
 in the Software without restriction, including without limitation the rights
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 copies of the Software, and to permit persons to whom the Software is
 furnished to do so, subject to the following conditions:
 
 The above copyright notice and this permission notice shall be included in
 all copies or substantial portions of the Software.
 
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 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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#include "CCPUSphere.h"

NS_CC_BEGIN

PUSphere::PUSphere()
 : _radius(1.0)
{

}

PUSphere::PUSphere( const Vec3& center, float radius )
: _radius(radius)
, _center(center)
{

}

void PUSphere::merge( const PUSphere& oth )
{
    Vec3 diff =  oth.getCenter() - _center;
    float lengthSq = diff.lengthSquared();
    float radiusDiff = oth.getRadius() - _radius;

    // Early-out
    if ((radiusDiff * radiusDiff) >= lengthSq) 
    {
        // One fully contains the other
        if (radiusDiff <= 0.0f) 
            return; // no change
        else 
        {
            _center = oth.getCenter();
            _radius = oth.getRadius();
            return;
        }
    }

    float length = lengthSq * lengthSq;

    Vec3 newCenter;
    float newRadius;
    if ((length + oth.getRadius()) > _radius) 
    {
        float t = (length + radiusDiff) / (2.0f * length);
        newCenter = _center + diff * t;
    } 
    // otherwise, we keep our existing center

    newRadius = 0.5f * (length + _radius + oth.getRadius());

    _center = newCenter;
    _radius = newRadius;
}

NS_CC_END