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MathNet.Spatial.Euclidean.Line3D retruns UnExpected NULL #239
Description
MathNet.Spatial.Euclidean.Line3D Intersection with Plane returns unexpected NULL:
//------------------------------------
// Immediate below FAILS, expecting (200, ~0, ~0) but receive aPtint = NULL:
MathNet.Spatial.Euclidean.Point3D LinePt1 = new Point3D(200, 0, 0);
MathNet.Spatial.Euclidean.Point3D LinePt2 = new Point3D(100, 0, 0);
Line3D a_Line3D = new Line3D(LinePt1, LinePt2);
Ap = -100; Bp = 0; Cp = -3.979039320256561E-13;
Vector3D aNormal = new Vector3D(Ap, Bp, Cp);
UnitVector3D aNormalV = aNormal.Normalize();
Point3D PtOnPlane = new Point3D(200, -100, 100);
Plane a_Plane = new Plane(PtOnPlane, aNormalV);
Point3D? aPtint = new Point3D();
aPtint = a_Line3D.IntersectionWith(a_Plane, 4.9E-324); //returns unexpected NULL.
//------------------------------------
Below DOES work, receives aPtint = (200, 0, 0);
MathNet.Spatial.Euclidean.Point3D LinePt1 = new Point3D(200, 0, 0);
MathNet.Spatial.Euclidean.Point3D LinePt2 = new Point3D(100, 0, 0);
Line3D a_Line3D = new Line3D(LinePt1, LinePt2);
Vector3D aNormal = new Vector3D(-100, 0, 0);
UnitVector3D aNormalV = aNormal.Normalize();
Point3D PtOnPlane = new Point3D(200, -100, 100);
Plane a_Plane = new Plane(PtOnPlane, aNormalV);
Point3D? aPtint = new Point3D();
aPtint = a_Line3D.IntersectionWith(a_Plane, 4.9E-324);
Notes:
_difference in above is changing Cp value from -3.979039320256561E-13 to 0;
_modification of error epsilon from 4.9E-324 to 0 etc did not change results.
_employing using VS 2017 fully updated; Working as expected for all other code within subject test.
Activity
ASCmetrology commentedon Dec 29, 2023
Apparently reason for listed ~issue is: Line SEGMENT is slightly ~short of penetrating the Plane.
We are desiring to determine Plane intersect with INFINITE Line.
Method suggestion appreciated.
jkalias commentedon Dec 29, 2023
I am not really sure I understood your explanation, can you explain it again with other words please?
ASCmetrology commentedon Dec 29, 2023
Reference the original posted FAILS code: That code returns NULL for the intersection (ie, No Intersect); I suggest This because the LINE is not considered infinite by MathNet. Using Ray3D in-place-of Line3D probably is the solution; However, I suspect would need to check BOTH directions (direct and mirror) of Ray to insure all tested for plane intersect.
jkalias commentedon Dec 31, 2023
I think the error lies in the implementation of
public Point3D? IntersectionWith(Line3D line, double tolerance = float.Epsilon)ofPlane.cs, which is identical topublic Point3D? IntersectionWith(LineSegment3D line, double tolerance = float.Epsilon)(notice,Line3Dvs.LineSegment3D).As far as I can tell, Spatial treats
Ray3Das an infinite (mathematical) line andLineSegment3Das a... segment of a line, with a given start and end.For my understanding,
Line3Dshould de removed and its usages replaced byRay3DJones-Adam commentedon Feb 22, 2024
Indeed, Line3D was at one point on the schedule to be deprecated