Check if two line segments intersect
Hi,
I've written some code below to check if two line segments intersect and if they do to tell me where. As input I have the (x,y) coordinates of both ends of each line. It appeared to be working correctly but now in the scenario where line A (532.87,787.79)(486.34,769.85) and line B (490.89,764.018)(478.98,783.129) it says they intersect at (770.136, 487.08) when the lines don' intersect at all.
Has anyone any idea what is incorrect in the below code? Thanks in advance
Code:
dy[0] = y2 - y1;
dx[0] = x2 - x1;
dy[1] = y4 - y3;
dx[1] = x4 - x3;
m[0] = dy[0] / dx[0];
m[1] = dy[1] / dx[1];
b[0] = y1 - m[0] * x1;
b[1] = y3 - m[1] * x3;
if (m[0] != m[1])
{
//slopes not equal, compute intercept
xint = (b[0] - b[1]) / (m[1] - m[0]);
yint = m[1] * xint + b[1];
//is intercept in both line segments?
if ((xint <= max(x1, x2)) && (xint >= min(x1, x2)) &&
(yint <= max(y1, y2)) && (yint >= min(y1, y2)) &&
(xint <= max(x3, x4)) && (xint >= min(x3, x4)) &&
(yint <= max(y3, y4)) && (yint >= min(y3, y4)))
{
if (xi && yi)
{
xi = xint;
yi = yint;
location_msg_ptr->current_latitude = xi;
location_msg_ptr->current_longitude = yi;
}
return(location_msg_ptr);
}
}
return(location_msg_ptr);
}