Determining if the circle intersects the given triangle

Hi, This is coming up when I am doing Finite Element Method: I've triangulation of the rectangle in 2d, and I am looping over the triangles. I also have few circle inside the rectangle. When I am in a current triangle, I want to find out if it intersects any of those circle, and if yes, how it intersects them, e.g. if it intersects one of the vertices, or only edges, or both. thanks

Answer 1

[John D'Errico]

We won't do your homework for you. This is just basic geometry. So do it.

1. Write down what it means for these objects to intersect. Do it on paper, forcing yourself to think clearly. If you don't bother thinking clearly about a problem, you cannot solve it. What must happen for an intersection?

2. Given the above step, define a set of tests to determine if there is an intersection.

3. Write matlab code for the above.

Only you can do this. And only you care about the result, as it is your homework, not ours.

[Aziz]

I do know how to do it using loops, but is it little longer. I was wondering if there is an easier way. E.g. can we define regions in matlab, e.g. if we have the vertices can we define triangle etc.

Answer 2

[Image Analyst]

Try the function called something like inpolygon(). If you know the perimeter coordinates, you're all set.