iphone - 如何使用cocos2d制作特定方向的箭头？

Question

我想要两个物体排成一排，如下所示，并让一个物体从下方拍摄它们，如下所示

                0 0 0 0 0 0 




                     0

下部始终处于其位置，并将射向上部，我想在用户在 iPhone 屏幕上移动手指时制作箭头，如下所示

                 0 0 0 0 0 0 

                   \
                    \
                     \
                      0

如果移动手指则

                  0 0 0 0 0 0                             
                      |
                      |
                      | 
                      0

在屏幕上将一根手指向右移动，则箭头应分别移动

                  0 0 0 0 0 0                             
                          /
                         /
                        /
                      0

我如何实现这个逻辑，我应该有多个数组图像并根据角度或其他方式使用它们，但我想要它的准确性。

谢谢

Answer 1

不需要多个图像......只需在touchesMoved方法中旋转箭头图像

尝试该代码。

UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:[touch view]];
location = [[CCDirector sharedDirector] convertToGL:location];


// Set up initial location of projectile
CGSize winSize = [[CCDirector sharedDirector] winSize];

// Rotate player to face shooting direction
CGPoint shootVector = ccpSub(location, sprite.position);
CGFloat shootAngle = ccpToAngle(shootVector);
CGFloat cocosAngle = CC_RADIANS_TO_DEGREES(-1 * shootAngle);

CGFloat curAngle = _player.rotation;
CGFloat rotateDiff = cocosAngle - curAngle;    
if (rotateDiff > 180)
    rotateDiff -= 360;
if (rotateDiff < -180)
    rotateDiff += 360;    

CGFloat rotateSpeed = 360; // degrees per second
CGFloat rotateDuration = fabs(rotateDiff / rotateSpeed);

[yoursprite runAction:[CCSequence actions:
                    [CCRotateTo actionWithDuration:rotateDuration angle:cocosAngle],
                    [CCCallFunc actionWithTarget:self selector:@selector(finishShoot)],
                    nil]];