检测旋转的 UIView 之间的碰撞

Question

我有两个 UIView，其中一个使用以下代码每 0.01 秒旋转一次：

    self.rectView.transform = CGAffineTransformRotate(self.rectView.transform, .05);

现在，我希望能够判断另一个 UIView（称为 view）是否与 rectView 相交。我使用了这段代码：

if(CGRectIntersectsRect(self.rectView.frame, view.frame)) {
    //Intersection
}

但是，正如您可能知道的那样，这有一个问题。这是一个屏幕截图：

在这种情况下，会检测到碰撞，即使它们显然没有接触。我环顾四周，但似乎找不到真正的代码来检测这种碰撞。如何才能做到这一点？在这种情况下检测碰撞的工作代码将不胜感激！或者也许除了 UIView 之外还有更好的类可以使用？

Answer 1

当你旋转视图时，它的边界不会改变but its frame changes.

所以，对于我的背景颜色蓝色，
我设置的初始帧是

帧 = (30, 150, 150, 35);
bounds={{0, 0}, {150, 35}};

但旋转45度后，框架变为

帧 = (39.5926 102.093; 130.815 130.815);
bounds={{0, 0}, {150, 35}};

因为框架总是返回那个视图的最小的封闭矩形。

因此，在您的情况下，即使看起来两个视图都没有相交，但它们的框架相交。

您可以使用分离轴测试来解决它。 如果你想学习它，link here

我试图解决它，最终得到了解决方案。 如果你想检查，下面是代码。 将以下代码复制粘贴到一个空项目中进行检查。

在 .m 文件中

@implementation ViewController{
    UIView *nonRotatedView;
    UIView *rotatedView;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    nonRotatedView =[[UIView alloc] initWithFrame:CGRectMake(120, 80, 150, 40)];
    nonRotatedView.backgroundColor =[UIColor blackColor];
    [self.view addSubview:nonRotatedView];

    rotatedView =[[UIView alloc] initWithFrame:CGRectMake(30, 150, 150, 35)];
    rotatedView.backgroundColor =[UIColor blueColor];
    [self.view addSubview:rotatedView];
    CGAffineTransform t=CGAffineTransformMakeRotation(M_PI_4);
    rotatedView.transform=t;

    CAShapeLayer *layer =[CAShapeLayer layer];
    [layer setFrame:rotatedView.frame];
    [self.view.layer addSublayer:layer];
    [layer setBorderColor:[UIColor blackColor].CGColor];
    [layer setBorderWidth:1];

    CGPoint p=CGPointMake(rotatedView.bounds.size.width/2, rotatedView.bounds.size.height/2);

    p.x = -p.x;p.y=-p.y;
    CGPoint tL =CGPointApplyAffineTransform(p, t);
    tL.x +=rotatedView.center.x;
    tL.y +=rotatedView.center.y;

    p.x = -p.x;
    CGPoint tR =CGPointApplyAffineTransform(p, t);
    tR.x +=rotatedView.center.x;
    tR.y +=rotatedView.center.y;

    p.y=-p.y;
    CGPoint bR =CGPointApplyAffineTransform(p, t);
    bR.x +=rotatedView.center.x;
    bR.y +=rotatedView.center.y;

    p.x = -p.x;
    CGPoint bL =CGPointApplyAffineTransform(p, t);
    bL.x +=rotatedView.center.x;
    bL.y +=rotatedView.center.y;


    //check for edges of nonRotated Rect's edges
    BOOL contains=YES;
    CGFloat value=nonRotatedView.frame.origin.x;
    if(tL.x<value && tR.x<value && bR.x<value && bL.x<value)
        contains=NO;
    value=nonRotatedView.frame.origin.y;
    if(tL.y<value && tR.y<value && bR.y<value && bL.y<value)
        contains=NO;
    value=nonRotatedView.frame.origin.x+nonRotatedView.frame.size.width;
    if(tL.x>value && tR.x>value && bR.x>value && bL.x>value)
        contains=NO;
    value=nonRotatedView.frame.origin.y+nonRotatedView.frame.size.height;
    if(tL.y>value && tR.y>value && bR.y>value && bL.y>value)
        contains=NO;

    if(contains==NO){
        NSLog(@"no intersection 1");
        return;
    }
    //check for roatedView's edges
    CGPoint rotatedVertexArray[]={tL,tR,bR,bL,tL,tR};

    CGPoint nonRotatedVertexArray[4];
    nonRotatedVertexArray[0]=CGPointMake(nonRotatedView.frame.origin.x,nonRotatedView.frame.origin.y);
    nonRotatedVertexArray[1]=CGPointMake(nonRotatedView.frame.origin.x+nonRotatedView.frame.size.width,nonRotatedView.frame.origin.y);
    nonRotatedVertexArray[2]=CGPointMake(nonRotatedView.frame.origin.x+nonRotatedView.frame.size.width,nonRotatedView.frame.origin.y+nonRotatedView.frame.size.height);
    nonRotatedVertexArray[3]=CGPointMake(nonRotatedView.frame.origin.x,nonRotatedView.frame.origin.y+nonRotatedView.frame.size.height);

    NSInteger i,j;
    for (i=0; i<4; i++) {
        CGPoint first=rotatedVertexArray[i];
        CGPoint second=rotatedVertexArray[i+1];
        CGPoint third=rotatedVertexArray[i+2];
        CGPoint mainVector =CGPointMake(second.x-first.x, second.y-first.y);
        CGPoint selfVector =CGPointMake(third.x-first.x, third.y-first.y);
        BOOL sign;
        sign=[self crossProductOf:mainVector withPoint:selfVector];
        for (j=0; j<4; j++) {
            CGPoint otherPoint=nonRotatedVertexArray[j];
            CGPoint otherVector = CGPointMake(otherPoint.x-first.x, otherPoint.y-first.y);
            BOOL checkSign=[self crossProductOf:mainVector withPoint:otherVector];
            if(checkSign==sign)
                break;
            else if (j==3)
                contains=NO;
        }
        if(contains==NO){
            NSLog(@"no intersection 2");
            return;
        }
    }
    NSLog(@"intersection");
}


-(BOOL)crossProductOf:(CGPoint)point1 withPoint:(CGPoint)point2{
    if((point1.x*point2.y-point1.y*point2.x)>=0)
         return YES;
    else
        return NO;
}

希望这会有所帮助。

Answer 2

这可以比建议的更有效和更容易地完成......如果需要，黑色和蓝色视图都可以旋转。

只需将旋转的 blueView 的 4 个角转换为它们在 superview 中的位置，然后将这些点转换为它们在旋转的 blackView 中的位置，然后检查这些点是否在 blackView 的范围内。

UIView *superview = blueView.superview;//Assuming blueView.superview and blackView.superview are the same...

CGPoint blueView_topLeft_inSuperview = [blueView convertPoint:CGPointMake(0, 0) toView:superview];
CGPoint blueView_topRight_inSuperview = [blueView convertPoint:CGPointMake(blueView.bounds.size.width, 0) toView:superview];
CGPoint blueView_bottomLeft_inSuperview = [blueView convertPoint:CGPointMake(0, blueView.bounds.size.height) toView:superview];
CGPoint blueView_bottomRight_inSuperview = [blueView convertPoint:CGPointMake(blueView.bounds.size.width, blueView.bounds.size.height) toView:superview];

CGPoint blueView_topLeft_inBlackView = [superview convertPoint:blueView_topLeft_inSuperview toView:blackView];
CGPoint blueView_topRight_inBlackView = [superview convertPoint:blueView_topRight_inSuperview toView:blackView];
CGPoint blueView_bottomLeft_inBlackView = [superview convertPoint:blueView_bottomLeft_inSuperview toView:blackView];
CGPoint blueView_bottomRight_inBlackView = [superview convertPoint:blueView_bottomRight_inSuperview toView:blackView];

BOOL collision = (CGRectContainsPoint(blackView.bounds, blueView_topLeft_inBlackView) ||
                  CGRectContainsPoint(blackView.bounds, blueView_topRight_inBlackView) ||
                  CGRectContainsPoint(blackView.bounds, blueView_bottomLeft_inBlackView) ||
                  CGRectContainsPoint(blackView.bounds, blueView_bottomRight_inBlackView));