 # How to check if a curve intersect with anything?

Hello.
I have problem, that would be easier to solve if I can check if a curve ever intersect with another. I know how to check between two curve using Rhino.Geometry.Intersect.Intersection.CurveCurve. What I want is that I have a curve then know if that curve ever intersect with another, then give me something (may be a list) about the intersection and with which curve. As I have lot of curves, I don’t like to iterating them one by one to check intersection if possible. Can anyone help? I’m using python for this.

Hi. Thanks for your answer. But, isn’t it kinda like check if the curve intersect with any member of a curve list by checking one by one? Though it happened inside a component, not by our own code.

You can use Intersection.CurveCurve like this:

``````private void RunScript(Curve a, Curve b, ref object A)
{
var tol = RhinoDocument.ModelAbsoluteTolerance;
var events = Rhino.Geometry.Intersect.Intersection.CurveCurve(a, b, tol, tol);
A = events.Count > 0;
}
``````

CurveCurve.gh (16.2 KB)

If your curves are coplanar you can use Curve.PlanarCurveCollision:

``````private void RunScript(Curve a, Curve b, ref object A)
{
var tol = RhinoDocument.ModelAbsoluteTolerance;
A = Curve.PlanarCurveCollision(a, b, Plane.WorldXY, tol);
}
``````

PlanarCurveCollision.gh (17.4 KB)

If you need to create the list inside your code:

``````private void RunScript(Curve a, List<Curve> obstacles, ref object A)
{
var tol = RhinoDocument.ModelAbsoluteTolerance;
var collisions = new List<bool>();
foreach(var obs in obstacles)
{
var events = Rhino.Geometry.Intersect.Intersection.CurveCurve(a, obs, tol, tol);
}
A = collisions;
}
``````

CurveCurveList.gh (15.0 KB)

You can also use System.Linq:

``````private void RunScript(Curve a, List<Curve> obstacles, ref object A)
{
var tol = RhinoDocument.ModelAbsoluteTolerance;
var collisions = obstacles.Select(obs => Intersection.CurveCurve(a, obs, tol, tol)).Select(events => events.Count > 0).ToList();
A = collisions;
}
``````

CurveCurveLinq.gh (15.0 KB)

If you only need to get the first intersected obstacle:

``````private void RunScript(Curve a, List<Curve> obstacles, ref object A)
{
var tol = RhinoDocument.ModelAbsoluteTolerance;
foreach(var obs in obstacles)
{
var events = Intersection.CurveCurve(a, obs, tol, tol);
if(events.Count == 0) continue;
A = obs;
break;
}
}
``````

firstObstacle.gh (14.4 KB)

1 Like

Moved to Rhino Developer sub-forum.

Hi. Thanks. I’ll try them

This was quite useful. Thank you for sharing.