cocos2d-x之CCCardinalSplineBy

CCCardinalSplineBy概念

这个类是样条曲线动作，其创建函数CCCardinalSplineBy::create(float duration, cocos2d::CCPointArray *points, float tension)；中duration是时间间隔，points是控制点列表，tension是松紧程度。tension==1时，样条线是分段直线。tension<1向外松弛弯曲，tension>1向内缩紧弯曲。By动作是以当前坐标为新坐标原点。

CCCardinalSplineBy示例–为同一组控制点实现不同的移动路径

CCSize s =CCDirector::sharedDirector()->getWinSize();CCPointArray*array =CCPointArray::create(20);
    array->addControlPoint(ccp(0,0));
    array->addControlPoint(ccp(s.width/2-30,0));
    array->addControlPoint(ccp(s.width/2-30, s.height-80));
    array->addControlPoint(ccp(0, s.height-80));
    array->addControlPoint(ccp(0,0));
//
// sprite 1 (By)
//
// Spline with no tension (tension==0)
//
CCCardinalSplineBy*action =CCCardinalSplineBy::create(3, array,0);
CCActionInterval*reverse = action->reverse();
CCFiniteTimeAction*seq =CCSequence::create(action, reverse, NULL);

    m_tamara->setPosition(ccp(50,50));
    m_tamara->runAction(seq);
//
// sprite 2 (By)
//
// Spline with high tension (tension==1)
//
CCCardinalSplineBy*action2 =CCCardinalSplineBy::create(3, array,1);
CCActionInterval*reverse2 = action2->reverse();
CCFiniteTimeAction*seq2 =CCSequence::create(action2, reverse2, NULL);

    m_kathia->setPosition(ccp(s.width/2,50));
    m_kathia->runAction(seq2);

由于By动作是以当前坐标为新坐标原点，所以在draw函数里设置openGL的原点位置

// move to 50,50 since the "by" path will start at 50,50
	kmGLPushMatrix();
	kmGLTranslatef(50,50,0);
	ccDrawCardinalSpline(m_pArray,0,100);
	kmGLPopMatrix();CCSize s =CCDirector::sharedDirector()->getWinSize();

	kmGLPushMatrix();
	kmGLTranslatef(s.width/2,50,0);
	ccDrawCardinalSpline(m_pArray,1,100);
	kmGLPopMatrix();

效果图如下： 注：

CCPointArray解释

CCPointArray是一个包含控制点的数组，使用方法如上