如何生成始终与 UIImage 当前位置左侧或右侧成 90 度角的“x,y”坐标？

Question

如何生成一个 x,y 始终与 UIImage 当前位置向左或向右 90 度的坐标？

我在 generateRandomLocation 中有一个随机 x, y 的位置。

我需要生成一个新的 x,y，它位于当前位置左侧 90 度或右侧 90 度。

然后我需要旋转图像，使其 "faces" 处于正确的位置。

我只是不确定如何计算 90 度。

尝试的解决方案；

不确定我做的是否正确。

CGPoint location;

    // Create airplane object
    for (int i=0; i<5; i++) {
        location = [self generateRandomLocation];

        VICAirplane *planeObj = [[VICAirplane alloc] init];
        planeObj.x = location.x;
        planeObj.y = location.y;
        planeObj.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(location.x, location.y, _spriteWidth, _spriteHeight)];
        planeObj.imageView.layer.anchorPoint = CGPointMake(0.5, 0.357); // Do not change this
        planeObj.imageView.backgroundColor = [UIColor redColor];
        planeObj.imageView.transform = CGAffineTransformIdentity;
        [planeObj.imageView setImage:_sprite];
        [self.worldMap addSubview:planeObj.imageView];

        //
        // Generate angle
        NSNumber *angle = [self.airplaneAngles firstObject];
        CGFloat angleToRotate = [angle floatValue]; // Will be 45 degrees

        //
        // You need two lines (two vectors) to form an angle.
        // The two vectors will be defined as:
        //  CA (calculated as A - C) and
        //  CB (calculated as B - C) where C is the center of rotation and A, B are the two points
        //
        CGPoint point = CGPointMake(planeObj.imageView.frame.origin.x + planeObj.imageView.layer.anchorPoint.x * planeObj.imageView.frame.size.width,
                                    planeObj.imageView.frame.origin.y + planeObj.imageView.layer.anchorPoint.y * planeObj.imageView.frame.size.height);

        CGFloat CA = location.x - point.x;
        CGFloat CB = location.y - point.y;

        CGVector v = CGVectorMake(CA, CB);

        CGVector vector = [self vectorFromVector:v rotateByAngle:angleToRotate];
        CGPoint newLocation = CGPointMake(vector.dx, vector.dy);

        //planeObj.imageView.transform = CGAffineTransformRotate(planeObj.imageView.transform, angleToRotate);
        planeObj.rotateToLocation = newLocation;
        planeObj.angleToRotate = angleToRotate;

        // Add to array
        [self.airplanes addObject:planeObj];
    }

Answer 1

试试这个：

将您的 CGPoint 转换为矢量然后使用：

 /*
  * Returns the vector rotated by an angle
  */
- (CGVector)vectorFromVector:(CGVector)vector rotatetByAngle:(CGFloat)radians{
    return CGVectorMake(cosf(radians) * vector.dx - sinf(radians) * vector.dy, sinf(radians) * vector.dx + cosf(radians) * vector.dy);
}

并转换回 CGPoint。

如何生成始终与 UIImage 当前位置左侧或右侧成 90 度角的“x,y”坐标？

How do I generate a `x,y` co-ordinates that is always 90 degrees either left or to the right of the current position of a UIImage?

math

angle

objective-c