axmol/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.

 https://axmolengine.github.io/

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#include "CCPUSphere.h"

NS_AX_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_AX_END