IOS Sprite 套件，旋转一个SKSpriteNode

Question

我在将 Sprite 节点旋转到触摸位置时遇到问题

这是我的代码:

#import "THMyScene.h"
#import <math.h>
#define SK_DEGREES_TO_RADIANS(__ANGLE__) ((__ANGLE__) * 0.01745329252f) // PI / 180
#define SK_RADIANS_TO_DEGREES(__ANGLE__) ((__ANGLE__) * 57.29577951f) // PI * 180

@implementation THMyScene
{
    CGSize _winSize;
    SKSpriteNode *_playerSprite;
}

-(id)initWithSize:(CGSize)size {    
    if (self = [super initWithSize:size]) {
        /* Setup your scene here */

        self.backgroundColor = [SKColor colorWithRed:94.0/255.0 green:63.0/255.0 blue:107.0/255.0 alpha:1.0];
        _winSize = CGSizeMake(self.size.width, self.size.height);
        _playerSprite = [SKSpriteNode spriteNodeWithImageNamed:@"Player"];
        _playerSprite.position  = CGPointMake(368.0f, 160.0f);

        [self addChild:_playerSprite];

    }
    return self;
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    /* Called when a touch begins */

    for (UITouch *touch in touches) {

        CGPoint touchLocation = [touch locationInNode:self];
        CGPoint spriteLocation = CGPointMake(_playerSprite.position.x, _playerSprite.position.y);
        float xDistance;
        float yDistance;

        xDistance = powf(touchLocation.x - spriteLocation.x,2);
        yDistance = powf(touchLocation.y - spriteLocation.y,2);



        float angle = atan2f(yDistance,xDistance);
        _playerSprite.zRotation = angle - SK_DEGREES_TO_RADIANS(90);
        SKAction *moveAction = [SKAction moveTo:touchLocation duration:2];
        [_playerSprite runAction: moveAction];
    }
}

-(void)update:(CFTimeInterval)currentTime {
    /* Called before each frame is rendered */
}

@end

关于问题可能是什么的任何建议

当我点击节点的右侧或顶部时，它会给我正确的方向但是当我点击节点的左侧或底部时，方向在相反的一侧。

Answer 1

您需要根据触摸的位置增加或减少 90 度。

float angle = atan2f(yDistance,xDistance);
if (spriteLocation.x > touchLocation.x) {
    _playerSprite.zRotation = angle + M_PI_2; //M_PI_2 is 90 degrees in radians
} else {
    _playerSprite.zRotation = angle - M_PI_2;
}