Make darts ninja (2) Cocos2d-x 3.0alpha0

 

The procedure is as follows:
1. Use the previous project;
2. Download the Resources required for this game and place the Resources under the Resources directory:

Delete old resources player.pngand projectile.png;
3. In the HelloWorldScene. cpp file, modify the init function to create a gamer genie:

 

        _player = Sprite::create(player2.png);

In the onTouchesEnded function, modify and create the bullet genie:

 

 

    Sprite* projectile = Sprite::create(projectile2.png);

4. Compile and run the task. You can see that the turret has shot a bullet, but it is strange that when shooting, the turret is not in that direction, as shown in:

 

5. Calculate the turret rotation angle. See the figure below:

The mathematical knowledge is that tan (angle) = the opposite side/adjacent side, use the arc tangent angle = arctan (the opposite side/adjacent side), then calculate the radian, and use the CC_RADIANS_TO_DEGREES macro to convert the angle. In mathematics, the Clockwise is positive, in the Cocos2D-x, clockwise is positive, as shown in:

Multiply the final calculated angle by-1. In the onTouchesEnded function, add the following code before the projectile genie runAction:

 

    float angleRadians = atanf((float)offRealY / (float)offRealX);    float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);    float cocosAngle = -1 * angleDegrees;    _player->setRotation(cocosAngle);

7. Compile and run the task. Now you can see the turret rotation and shooting. As shown in:

 

 

8. Rotate before shooting. The turret rotation is completed in an instant, which is not in line with reality and requires an action to move the turret. In the HelloWorldScene. h file, add the following statement:

 

    Sprite* _nextProjectile;

In the constructor, add the following:

 

 

    _player = NULL;    _nextProjectile = NULL;

Modify the onTouchesEnded function and add FinishShootThe Code is as follows:

 

 

void HelloWorld::onTouchesEnded(const std::vector
 
   &touches, cocos2d::Event *event){    if (_nextProjectile != NULL) {        return;    }            Touch* touch = touches.front();    Point location = this->convertTouchToNodeSpace(touch);            Size winSize = Director::getInstance()->getWinSize();        _nextProjectile = Sprite::create(projectile2.png);    _nextProjectile->retain();    _nextProjectile->setScale(2);    _nextProjectile->setPosition(Point(20, winSize.height / 2));        Point offset = ccpSub(location, _nextProjectile->getPosition());        if (offset.x <= 0) {        return;    }               int realX = winSize.width + _nextProjectile->getContentSize().width / 2;    float ratio = (float)offset.y / (float)offset.x;    int realY = realX * ratio + _nextProjectile->getPosition().y;    Point realDest = Point(realX, realY);        int offRealX = realX - _nextProjectile->getPosition().x;    int offRealY = realY - _nextProjectile->getPosition().y;    float length = sqrtf(offRealX * offRealX + offRealY * offRealY);    float velocity = 480 / 1;        float realMoveDuration = length / velocity;        float angleRadians = atanf((float)offRealY / (float)offRealX);    float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);    float cocosAngle = -1 * angleDegrees;        float rotateDegreesPerSecond = 180 / 0.5;    float degreesDiff = _player->getRotation() - cocosAngle;    float rotateDuration = fabs(degreesDiff / rotateDegreesPerSecond);    RotateTo* rotate = RotateTo::create(rotateDuration, cocosAngle);    CallFunc* callFc = CallFunc::create(std::bind(&HelloWorld::finishShoot, this));        _player->runAction(Sequence::create(rotate,callFc, NULL));            _nextProjectile->runAction(Sequence::create(MoveTo::create(realMoveDuration, realDest),                                                CallFuncN::create(std::bind(&HelloWorld::spriteMoveFinished, this,_nextProjectile)), NULL));    _nextProjectile->setTag(2);        }void HelloWorld::finishShoot(){    this->addChild(_nextProjectile);    _projectiles->addObject(_nextProjectile);    _nextProjectile->release();    _nextProjectile = NULL;}
 

Check the _ nextProjectile variable at the beginning of the function. If it is not empty, the turret is being rotated. Do not add _ nextProjectile to the scenario immediately, and wait until the rotation is complete before joining the scenario. The rotation speed of the turret. The rotation speed is half a circle in half a second, and the time required to calculate the rotation angle.
9. Compile and run the task. You can see that the turret is shot after rotation, as shown in:


References:
1. How To Make A Simple iPhone Game with Cocos2D 2.X Part 2 http://www.raywenderlich.com/25791/rotating-turrets-how-to-make-a-simple-iphone-game-with-cocos2d-2-x-part-2
2. How to Use cocos2d to develop a simple iphone game: rotating turret. Http://www.cnblogs.com/zilongshanren/archive/2011/03/28/1997820.html (Part 2)
Thank you very much for the above materials. In this example, additional resources are added to the source code. : Http://pan.baidu.com/s/16Bp7h
If there is an error in the article, please point it out for correction. You are welcome to leave a message to discuss the technology!