將新的CGPoint值與數組中的CGPoint值進行比較

Question

我正在生成具有隨機位置的多個圓圈。我想要阻止的是圈子彼此重疊。所以我想將新生成的CGPoint值與數組中的值進行比較，如果該值發現自己位於其中一個CGPoint的半徑區域中，則會生成一個新值。

除了重疊之外，我得到了大部分內容。 我已經評論過我嘗試過的部分，但那並不真正有效（有缺陷的邏輯）。 我不確定如何迭代CGPoint的各個值並對它們進行比較。

更新： 我已經更改了一些代碼，並添加了一個檢查，看看CGPoint是否會重疊。問題是每當我想嘗試像

while (!xPointOk || !yPointOk) { 

// generate new values 

} 

我一直陷入無限循環。

- (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

當新點小於任何現有點的圓周時，您的測試應該失敗，因此您可以使用基本的三角函數來解決問題。

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); 

其他事情你需要考慮的是要重試多少次來停止無限次的重試。