Question

Can anyone please help.

I have a problem where I need to loop through 3 lines and check if they are intersecting using C#. The 3 lines will make up the general shape of a triangle. Therefore, only 2 lines will ever be intersecting at a a time.

I have 3 Line objects and I have stored them in List lines.
My method to check for intersections currently looks like this:

ProcessIntersections(lines[0], lines[1])
ProcessIntersections(lines[1], lines[2])
ProcessIntersections(lines[2], lines[0])

Looping through the list once I can do, but to check the final intersection, I have to pass in the first line again and check it against the last line.

Is there a better way to process my intersections?
How would I be able to loop through the list of lines by only calling ProcessIntersections once?
I tried:

for (int i = 0; i < lines.Count; i++)
{
    if (i >= 3)
    {
        i = 0;
        ProcessIntersection(lines[i], lines[i + 1]);
    }
}

But this just lands me in an infinite loop as i keeps on resetting to 0.

Does anyone have any suggestions.

Answer 1

Try next loop:

for (int i = 0; i < lines.Count; i++)
{
  var next_i = i + 1;
  if (next_i >= lines.Count)
    next_i = 0;
  ProcessIntersection(lines[i], lines[next_i]);
}

or optimized loop:

for (int i = 0; i < lines.Count; i++)
{
  ProcessIntersection(lines[i], lines[(i + 1) % lines.Count]);
}