# Is Point on Curve?

Hi everyone…
I have some points and curves (edges). How to decide that a point is on a particular curve, is there some function in Rhino SDK?
Thanks

Not sure if there’s a specific function that does what you want, but you could try Curve.ClosestPoint():
http://4.rhino3d.com/5/rhinocommon/html/M_Rhino_Geometry_Curve_ClosestPoint_1.htm

Setting the max distance appropriately low should return false if the point is not on the curve.

There is the method on the Curve class class Contains:
http://4.rhino3d.com/5/rhinocommon/html/M_Rhino_Geometry_Curve_Contains.htm

``````// small example
Curve c;
PointContainment pc = c.Contains(pt);
bool isOnCurve = pc.Equals(PointContainment.Coincident);``````

``````bool IsPointOnCurve(
const ON_Curve* curve,
const ON_3dPoint& point,
double tolerance
)
{
bool rc = false;
if (0 != curve)
{
if( tolerance < ON_SQRT_EPSILON )
tolerance = ON_SQRT_EPSILON;

double t = 0.0;
if( curve->GetClosestPoint(point, &t) )
{
ON_3dPoint pt;
if( curve->EvPoint(t, pt) )
{
if( point.DistanceTo(pt) <= tolerance )
rc = true;
}
}
}

return rc;
}
``````