确定线是否与CGRect相交

本文介绍了确定线是否与CGRect相交的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在寻找类似这样的东西：

CGPoint startLine = CGPointMake（5.0f，5.0f）; CGPoint endLine = CGPointMake（25.0f，25.0f）; CGRect intersectingRect = CGRectMake（10.0f，10.0f，50.0f，50.0f）; if（CGRectContainsLine（intersectingRect，startLine，endLine））{// true //线与矩形相交} 解决方案

没有内置内容，但是应该这样做：

BOOL RectContainsLine（CGRect r，CGPoint lineStart，CGPoint lineEnd） { BOOL（^ LineIntersectsLine）（CGPoint，CGPoint，CGPoint，CGPoint）= ^ BOOL （CGPoint line1Start，CGPoint line1End，CGPoint line2Start，CGPoint line2End） { CGFloat q = //线条起始行之间的距离乘以line2的水平长度（line1Start.y - line2Start.y）*（line2End.x - line2Start.x） //线条起始列之间的距离乘以line2的垂直长度 - （line1Start.x - line2Start.x）*（line2End。 y - line2Start.y）; CGFloat d = //第1行的水平长度乘以第2行的垂直长度（line1End.x - line1Start.x）*（line2End.y - line2Start.y） / / Line 1的垂直长度乘以第2行的水平长度 - （line1End.y - line1Start.y）*（line2End.x - line2Start.x）; if（d == 0） return NO; CGFloat r = q / d; q = //线条起始行之间的距离乘以第1行的水平长度（line1Start.y - line2Start.y）*（line1End.x - line1Start.x） //线条起始列之间的距离乘以第1行的垂直长度 - （line1Start.x - line2Start.x）*（line1End.y - line1Start.y）; CGFloat s = q / d; if（r 1 || s 1） return NO; 返回YES; }; / *测试该线是否与以下任何一个相交： * - 矩形的底部边缘 * - 矩形的右边缘 * - 顶部矩形的边缘 * - 矩形的左边缘 * - 矩形的内部（两个点都在里面） * / return（LineIntersectsLine lineStart，lineEnd，CGPointMake（r.origin.x，r.origin.y），CGPointMake（r.origin.x + r.size.width，r.origin.y））|| LineIntersectsLine（lineStart， lineEnd，CGPointMake（r.origin.x + r.size.width，r.origin.y），CGPointMake（r.origin.x + r.size.width，r.origin.y + r.size.height）） || LineIntersectsLine（lineStart，lineEnd，CGPointMake（r.origin.x + r.size.width，r.origin.y + r.size.height），CGPointMake（r.origin.x，r.origin .y + r.size.height））|| LineIntersectsLine（lineStart，lineEnd，CGPointMake（r.origin.x，r.origin.y + r.size.height），CGPointMake（r.origin.x ，r.origin.y））|| （CGRectC ontainsPoint（r，lineStart）&& CGRectContainsPoint（r，lineEnd）））; }

从这个问题中移出：如何知道一条线是否与矩形相交

What is the most efficient way to determine if a line intersects a rectangle?

I'm looking for something similar to this:

CGPoint startLine = CGPointMake(5.0f,5.0f); CGPoint endLine = CGPointMake(25.0f,25.0f); CGRect intersectingRect = CGRectMake(10.0f,10.0f,50.0f,50.0f); if (CGRectContainsLine(intersectingRect,startLine,endLine)) { //true //line intersects rectangle }

解决方案

There's nothing built in, but this ought to do it:

BOOL RectContainsLine(CGRect r, CGPoint lineStart, CGPoint lineEnd) { BOOL (^LineIntersectsLine)(CGPoint, CGPoint, CGPoint, CGPoint) = ^BOOL(CGPoint line1Start, CGPoint line1End, CGPoint line2Start, CGPoint line2End) { CGFloat q = //Distance between the lines' starting rows times line2's horizontal length (line1Start.y - line2Start.y) * (line2End.x - line2Start.x) //Distance between the lines' starting columns times line2's vertical length - (line1Start.x - line2Start.x) * (line2End.y - line2Start.y); CGFloat d = //Line 1's horizontal length times line 2's vertical length (line1End.x - line1Start.x) * (line2End.y - line2Start.y) //Line 1's vertical length times line 2's horizontal length - (line1End.y - line1Start.y) * (line2End.x - line2Start.x); if( d == 0 ) return NO; CGFloat r = q / d; q = //Distance between the lines' starting rows times line 1's horizontal length (line1Start.y - line2Start.y) * (line1End.x - line1Start.x) //Distance between the lines' starting columns times line 1's vertical length - (line1Start.x - line2Start.x) * (line1End.y - line1Start.y); CGFloat s = q / d; if( r < 0 || r > 1 || s < 0 || s > 1 ) return NO; return YES; }; /*Test whether the line intersects any of: *- the bottom edge of the rectangle *- the right edge of the rectangle *- the top edge of the rectangle *- the left edge of the rectangle *- the interior of the rectangle (both points inside) */ return (LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x, r.origin.y), CGPointMake(r.origin.x + r.size.width, r.origin.y)) || LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x + r.size.width, r.origin.y), CGPointMake(r.origin.x + r.size.width, r.origin.y + r.size.height)) || LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x + r.size.width, r.origin.y + r.size.height), CGPointMake(r.origin.x, r.origin.y + r.size.height)) || LineIntersectsLine(lineStart, lineEnd, CGPointMake(r.origin.x, r.origin.y + r.size.height), CGPointMake(r.origin.x, r.origin.y)) || (CGRectContainsPoint(r, lineStart) && CGRectContainsPoint(r, lineEnd))); }

Trivially ported from this question: How to know if a line intersects a rectangle