//兩點之間的距離
double juli(int x1,int y1,int x2,int y2)
{
	return sqrt(double((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2)));
}
//輸入經過霍夫變換得到的直線  儲存起點和終點的vector  直線最短距離  點之間間隔最長距離
void HoughLinesP(Mat &img,vector<Vec2f> &lines,vector<Vec4i> &points, double minLineLength=0,double maxLineGap=1)
{
	Vec4i point;
	uchar *p; 
	float r,theta;
	bool start,end;
	int x,y;

	for(size_t i = 0;i < lines.size(); i++)
	{
		r = lines[i][0];
		theta = lines[i][1];
		start = false;
		end = false;
		//水平 極徑與x軸90 直線與x軸0
		if(sin(theta) > 0.99999)
		{
			y = cvRound(r);
			p = img.ptr<uchar>(y);
			for(x = 0; x < img.cols; x++)
			{
				if( (p[x] != 0) || (x == img.cols - 1) )
				{
					//起點
					if(start == false)
					{
						point[0] = x;
						point[1] = y;
						start = true;
						continue;
					}
					//終點
					if(end == false)
					{
						//初始一個終點
						if(juli(point[0],point[1],x,y) <= maxLineGap)
						{
							point[2] = x;
							point[3] = y;
							end = true;
						}
						//不符合則重新確立起點
						else
						{
							point[0] = x;
							point[1] = y;
						}
						continue;
					}
					//移動終點
					if(juli(point[2],point[3],x,y) <= maxLineGap)
					{
						point[2] = x;
						point[3] = y;
					}
					else
					{
						//確定一條直線
						if(juli(point[0],point[1],point[2],point[3]) >= minLineLength)
						{
							points.push_back(point);
						}
						start = false;
						end = false;
					}
				}
			}
		}
		else
		{
			for(y = 0; y < img.rows; y++)
			{
				x = cvRound((r-y*sin(theta))/cos(theta));
				p = img.ptr<uchar>(y);
				if( (p[x] != 0) || (y == img.rows - 1) )
				{
					//起點
					if(start == false)
					{
						point[0] = x;
						point[1] = y;
						start = true;
						continue;
					}
					//終點
					if(end == false)
					{
						//初始一個終點
						if(juli(point[0],point[1],x,y) <= maxLineGap)
						{
							point[2] = x;
							point[3] = y;
							end = true;
						}
						//不符合則重新確立起點
						else
						{
							point[0] = x;
							point[1] = y;
						}
						continue;
					}
					//移動終點
					if(juli(point[2],point[3],x,y) <= maxLineGap)
					{
						point[2] = x;
						point[3] = y;
					}
					else
					{
						//確定一條直線
						if(juli(point[0],point[1],point[2],point[3]) >= minLineLength)
						{
							points.push_back(point);
						}
						start = false;
						end = false;
					}
				}
			}
		}
	}
}