技术经验分享：cocos3抛物线运动

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#pragma once

#include ""cocos2d.h""

USING_NS_CC;

class Parabola:public ActionInterval

{

public:

static Parabola* create(const CCPoint& startPosition, const CCPoint& endPosition,

float //代码效果参考：https://v.youku.com/v_show/id_XNjQwNjg1ODY3Ng==.html

angle, float g,float &return_duration);

//override

virtual Parabola* clone() const override;

virtual Parabola* reverse() const override;

virtual void update(float time) override;

protected:

bool initWithDuration(float duration, const CCPoint& startPosition,

const CCPoint& endPosition, float angle, float g, float vx0, float vy0);

protected:

float m_vx0;

float m_vy0;

Point m_startPosition;

Point m_endPosition;

float m_angle;

float m_dur ;

float m_tan_a;

float m_g;

};

#include ""Parabola.h""

#define PIXELS_PER_METER 100

Parabola* Parabola::create(const CCPoint& startPosition, const CCPoint& endPosition,

float angle, float g,float &return_duration)

{

Parabola *pRet = new Parabola();

float vx0,vy0, x1, y1, duration;

x1 = endPosition.x - startPosition.x;

y1 = endPosition.y - startPosition.y;

x1 /= PIXELS_PER_METER; //像素到米的转换，PIXELS_PER_METER为转换系数，这里设置为100

y1 /= PIXELS_PER_METER;

angle = angle*3.14 / 180;//convert t to radian

if (x1[span style=""color: rgba(128, 0, 128, 1)"">0)

{

angle *= -1;

}

vx0 = x1sqrt(g / 2 / (x1tan(angle) - y1)); //求出初速度

vy0 = vx0 * tan(angle);

duration = x1 / vx0; //求出整个运动的时间

return_duration = duration; //将duration通过参数返回

pRet->initWithDuration(duration,startPosition, endPosition, angle,g, vx0, vy0);

pRet->autorelease();

return pRet;

}

bool Parabola::initWithDuration(float duration, const Point& startPosition, const Point& endPosition, float angle, float g, float vx0, float vy0)

{

if (CCActionInterval::initWithDuration(duration))

{

m_vx0 = vx0;

m_vy0 = vy0;

m_startPosition = startPosition;

m_endPosition = endPosition;

angle = angle*3.14 / 180;//convert t to radian

m_angle = angle;

m_dur = duration;

m_tan_a = tan(angle);

m_g = g;

//代码效果参考： https://v.youku.com/v_show/id_XNjQwMDQxMTcwNA==.html

return true;

}

return false;

}

Parabola* Parabola::clone() const

{

CC_ASSERT(0);

return nullptr;

}

Parabola* Parabola::reverse() const

{

CC_ASSERT(0);

return nullptr;

}

void Parabola::update(float time)

{

if (_target)

{

float elapsed = _elapsed; //获得当前的运动时间

float diff_x = m_vx0 * elapsed;

float diff_y = m_vy0 elapsed - 0.5 m_g elapsed elapsed;

CCPoint newPos = ccpAdd(m_startPosition, ccp(diff_x PIXELS_PER_METER, diff_y PIXELS_PER_METER)); //单位由米转换为像素

_target->setPosition(newPos);

}

}

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