Objective c iOS精灵套件如何使投射物指向横向目标？

我在我的精灵套件游戏中有一个图标，当一个角色射击另一个角色时，我打算用它作为动画投射物。我正试着让这个射弹指向目标

我将它旋转一个π/4.0的底角，使它直接指向右边。然后我希望箭头从这个位置旋转并指向目标

下面的代码几乎可以工作，但在我看来，它总是看起来好像炮弹偏离了正确的角度。如果角度正确，当向箭头提供移动到目标x、y坐标的动作时，箭头将指向移动方向

如何正确计算从一个（x，y）点到另一个（x，y）点的发射角度？

//correct for pointing in the bottom right corner    
    float baseRotation = M_PI/4.0;   
    float zeroCheckedY = destination.y - origin.y;
    float zeroCheckedX = destination.x - origin.x;
    SKAction* rotate = nil;
    if(zeroCheckedX != 0)
    {
//not sure if I'm calculating this angle correctly.
        float angle =  atanf(zeroCheckedY/zeroCheckedX);
        rotate =  [SKAction rotateByAngle:baseRotation + angle duration:0];
    }else
    {
        rotate =  [SKAction rotateByAngle:baseRotation duration:0];

    }

编辑：下面的代码现在可以工作了，只需要执行zeroCheckedY/zeroCheckedX。

//correct for pointing in the bottom right corner    
    float baseRotation = M_PI/4.0;   
    float zeroCheckedY = destination.y - origin.y;
    float zeroCheckedX = destination.x - origin.x;
    SKAction* rotate = nil;
    if(zeroCheckedX != 0)
    {
//not sure if I'm calculating this angle correctly.
        float angle =  atanf(zeroCheckedY/zeroCheckedX);
        rotate =  [SKAction rotateByAngle:baseRotation + angle duration:0];
    }else
    {
        rotate =  [SKAction rotateByAngle:baseRotation duration:0];

    }

---

我有一个类似的问题：加农炮必须“跟踪”目标。 在

CannonNode

中，我定义了以下方法：

- (void)catchTargetAtPoint:(CGPoint)target {
    CGPoint cannonPointOnScene = [self.scene convertPoint:self.position fromNode:self.parent];
    float angle = [CannonNode pointPairToBearingDegreesWithStartingPoint:cannonPointInScene endingPoint:target];
    if (self.zRotation < 0) {
        self.zRotation = self.zRotation + M_PI * 2;
    }
    if ((angle < self.maxAngle) && (angle> self.minAngle)) {
        [self runAction:[SKAction rotateToAngle:angle duration:1.0f]];
    }
}

+ (float)pointPairToBearingDegreesWithStartingPoint:(CGPoint)startingPoint endingPoint:(CGPoint) endingPoint {
    CGPoint originPoint = CGPointMake(endingPoint.x - startingPoint.x, endingPoint.y - startingPoint.y); // get origin point to origin by subtracting end from start
    float bearingRadians = atan2f(originPoint.y, originPoint.x); // get bearing in radians
    return bearingRadians;
}

-（无效）捕获目标点：（CGPoint）目标{
CGPoint cannonPointOnScene=[self.scene convertPoint:self.positionfromNode:self.parent]；
浮动角度=[CannonNode PointPairToBearingDegrees with StartingPoint:cannonPointInScene endingPoint:target]；
if（自旋转<0）{
self.zRotation=self.zRotation+M_PI*2；
}
如果（（角度self.minAngle））{
[自运行：[SKAction rotateToAngle:角度持续时间：1.0f]；
}
}
+（浮动）点对承载度数与起点：（CGPoint）起点终点：（CGPoint）终点{
CGPoint originPoint=CGPointMake（endingPoint.x-startingPoint.x，endingPoint.y-startingPoint.y）；//通过从起点减去终点得到原点到原点
float bearingRadians=atan2f（originPoint.y，originPoint.x）；//以弧度获取方向角
回归英格拉迪亚；
}

必须在场景的

update

方法中调用

catchTargetPoint