ios - 将新的 CGPoint 值与数组中的 CGPoint 值进行比较

Question

我正在生成一些位置随机的圆圈。我要防止的是圆圈相互重叠。所以我想将新生成的 CGPoint 值与数组中的值进行比较，如果该值位于其中一个 CGPoint 的半径区域中，则让它生成一个新值。

除了重叠的东西，我得到了大部分。我已经对我尝试过的部分进行了评论，但这并没有真正起作用(有缺陷的逻辑)。我不确定如何遍历 CGPoint 的各个值并比较它们。

更新:我对代码做了一些更改，并添加了一个检查以查看 CGPoint 是否会重叠。问题是每当我想尝试类似

while (!xPointOk || !yPointOk) {

// generate new values

}

我一直陷入无限循环。

- (void) positionCircles 
{

    //generate random Y value within a range
    int fromNumberY = 500;
    int toNumberY = 950;
    int randomNumberY =(arc4random()%(toNumberY-fromNumberY+1))+fromNumberY;

    //generate random Y value within a range
    int fromNumberX = 0;
    int toNumberX = 700;
    int randomNumberX = (arc4random()%(toNumberX-fromNumberX+1))+fromNumberX;

    //array to hold all the the CGPoints
    positionsArray = [[NSMutableArray alloc] init];
    CGPoint circlePositionValue;

    CGFloat radius = 70;

    CGRect position = CGRectMake(randomNumberX,randomNumberY, radius, radius);

    [self makeColors];



    // create a circle for each color in color array
    for (int i = 0; i < [colors count];i++)
    {
        // generate new position before placing new cirlce
        randomNumberX = (arc4random()%(toNumberX-fromNumberX+1))+fromNumberX;
        randomNumberY = (arc4random()%(toNumberY-fromNumberY+1))+fromNumberY;

        circlePositionValue = CGPointMake(position.origin.x, position.origin.y);

        for (NSValue *value in positionsArray) {


            BOOL xPointOk = (randomNumberX < value.CGPointValue.x - radius) || 
                             (randomNumberX > value.CGPointValue.x + radius);

            BOOL yPointOk = (randomNumberY < value.CGPointValue.y - radius) || 
                             (randomNumberY > value.CGPointValue.y + radius);


            NSLog(@"xPoint: %i - %f", randomNumberX , value.CGPointValue.x);
            NSLog(@"xPoint ok? %@", xPointOk?@"yes":@"no");

            NSLog(@"yPoint: %i - %f", randomNumberY , value.CGPointValue.y);
            NSLog(@"yPoint ok? %@", yPointOk?@"yes":@"no");
            NSLog(@"___");

        }

        position.origin.x = randomNumberX;
        position.origin.y = randomNumberY;
        [positionsArray addObject:[NSValue valueWithCGPoint:circlePositionValue]];

        Circle *myCircle = [[Circle alloc] initWithFrame:position radius:radius color:[colors objectAtIndex:i]];
        myCircle.label.text = [NSString stringWithFormat:@"%i", i];
        [self.view addSubview:myCircle];

    }

}

Answer 1

当新点小于距任何现有点的圆周时，您的测试应该会失败，因此您可以使用基本三角来计算它。

BOOL far_enough_away = NO;
CGPoint newpoint = CGZeroPoint;
while(!far_enough_away)
{
    newpoint = randomisation_thingy();
    far_enough_away = YES;
    for(NSValue *existing in positionsArray)
    {
        CGPoint pointb = [existing pointValue];
        CGFloat deltay = pointb.y-newpoint.y;
        CGFloat deltax = pointb.x-newpoint.x;
        CGFloat distance = sqrt(pow(deltax,2) + pow(deltay,2));
        //fail if closer than desired radius
        if(distance < circumference )
        {
           //sadness - try again
           far_enough_away = NO;
           break;
        }
    }
}
create_a_new_circle_at_point(newpoint);

您需要考虑的其他事情是重试多少次以停止无限次重试。