Question

我开始学习游戏开发。作为初学者，我创建了一个演示游戏，其中一个大炮向敌人发射子弹（从不同方向向大炮射击）。现在我坚持使用用户触摸屏幕或敌人的大炮精灵图像旋转。我是怎么做到的，我的初始代码如下，

void HelloWorld:: ccTouchesBegan(CCSet *touches, CCEvent * event)
{
    CCSize winSize = CCDirector::sharedDirector()->getWinSize(); 
    CCTouch* touch = (CCTouch*)( touches->anyObject() );
    CCPoint location = touch->locationInView(touch->view());
    location = CCDirector::sharedDirector()->convertToGL(location);

    //Rotate cannon direction toward touch point
    CCPoint diffPoint = ccpSub(_cannonImage->getPosition(), location);
    float angleRadians = atanf((float)diffPoint.y/(float)diffPoint.x);
    float angleOffset = CC_DEGREES_TO_RADIANS(180);

    if(diffPoint.x < 0){
        angleRadians += angleOffset;
    }else{
        angleRadians -= angleOffset;
    }

    CCLog("angle to be rotate = %f", angleRadians);

    _cannonImage->runAction(CCRotateBy::actionWithDuration(0.1, angleRadians));

}

代码用cocos2d-x编写。我也接受了用普通cocos2d写的人的回答。

由于 iHungry

Answer 1

完美的答案如下，

float HelloWorld::changingAngleAccordingToCoordinateSystem(CCPoint imageCenter, CCPoint touchLocation, float calculatedAngle){

//Consideration :- all Angles is in Degree 
if((calculatedAngle >= 0 && calculatedAngle <= 90) || (calculatedAngle >= 90 && calculatedAngle <= 180)){
    //Ist quardant
    calculatedAngle = calculatedAngle;
}
else if(calculatedAngle < 0 && calculatedAngle >= -90){
    //IInd quardant
    calculatedAngle = 270 + (90 + calculatedAngle);
} 
else if(calculatedAngle < -90 && calculatedAngle >= -180){
    calculatedAngle = 180 + (180 + calculatedAngle);
}

return calculatedAngle;
}


//Rotate cannon direction toward touch point
float diff_X = touchLocation.x - myImage->getPosition().x;
float diff_Y = touchLocation.y - myImage->getPosition().y;
CCPoint diffPoint = CCPoint(diff_X, diff_Y);
float angleRadians = atan2f(diffPoint.y,diffPoint.x);
angleRadians = CC_RADIANS_TO_DEGREES(angleRadians);
angleRadians = HelloWorld::changingAngleAccordingToCoordinateSystem(myImage->getPosition(), touchLocation, angleRadians);
myImage->setRotation(-angleRadians);

Answer 2

我用这段代码来旋转我的精灵。我根据我的加速度计读数移动了精灵。

float angleRadians =-accelX;
float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);
objGlider->sprite_Glider.rotation = cocosAngle;

检查一下。缓慢的原因可能是您可能在代码中使用CClog或NSLog。

这是完整的代码。

if(!boolPlayerDied)
{
    static float prevX=0, prevY=0;
    #define kFilterFactor 1.0f// don't use filter. the code is here just as an example
    float accelX = (float) acceleration.x * kFilterFactor + (1- kFilterFactor)*prevX;
    float accelY = (float) acceleration.y * kFilterFactor + (1- kFilterFactor)*prevY;
    prevX = accelX;
    prevY = accelY;
    accelX = accelX-0.5;// Angle check fot tgfor the player to play
    float angleRadians =-accelX;
    float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);
    if(accelX>0)
    {
        cocosAngle = 1.1 * angleDegrees;
    }
    else
    {
        if(accelX<-0.5)
            accelX=-0.5;
        cocosAngle = 1.1  * angleDegrees;
    }
    objGlider->sprite_Glider.rotation = cocosAngle;
}

objGlider是创建滑翔机精灵的类的对象，而sprite_Glider是滑翔机类中使用的精灵。

您可以使用rotation属性旋转您的精灵。在cocos2Dx中，它可能是setRotation。

Answer 3

首先，替换

float angleRadians = atanf((float)diffPoint.y/(float)diffPoint.x);
float angleOffset = CC_DEGREES_TO_RADIANS(180);

if(diffPoint.x < 0){
    angleRadians += angleOffset;
}else{
    angleRadians -= angleOffset;
}

通过

float angleRadians = atan2f(diffPoint.y, diffPoint.x);

然后最好立即设置旋转（没有动作）来处理多个频繁的触摸。

_cannonImage->setRotation(angleRadians);

也许您需要像setRotation(-angleRadians)或setRotation(angleRadians+90)那样调整轮播 - 这取决于您的坐标系。

根据用户触摸位置旋转精灵图像？

3 个答案: