Minor fix in test for Cylinder3

Summary:
Follow-up for D87401326. The or a problem persisted:

https://github.com/facebookresearch/ocean/actions/runs/19528205954/job/55905174755#step:7:784

Fixed a crash in CylinderT3::nearestIntersection() and TestCylinder3 when handling rays that are parallel or nearly parallel to the cylinder axis.

The quadratic equation solver EquationT<T>::solveQuadratic() has an assertion that the quadratic coefficient 'a' must be non-zero. However, when computing ray-cylinder intersections, 'a' equals [d^T·d - (d^T·q)^2], which can be approximately zero when the ray direction d is parallel to the cylinder axis q.

Added NumericT<T>::isNotEqualEps(a) checks before calling solveQuadratic() in:
1. Cylinder3.h: nearestIntersection() method
2. TestCylinder3.cpp: ground-truth calculation in test

This matches the pattern already used in TestCone3.cpp and properly handles floating-point edge cases.

Reviewed By: janherling

Differential Revision: D87572921

fbshipit-source-id: 7289e7b0354d9627d87160c8f1ab10f77e652af0

Author: enpe

impl/ocean/math/Cylinder3.h

@@ -283,7 +283,7 @@ bool CylinderT3<T>::nearestIntersection(const LineT3<T>& ray, VectorT3<T>& inter
 
 	T minDistance = T(-1.), maxDistance = T(-1.);
 
-	if (EquationT<T>::solveQuadratic(a, b, c, minDistance, maxDistance))
+	if (NumericT<T>::isNotEqualEps(a) && EquationT<T>::solveQuadratic(a, b, c, minDistance, maxDistance))
 	{
 		minDistance = min(minDistance, maxDistance);
 	}
@@ -317,4 +317,3 @@ inline bool CylinderT3<T>::isValid() const
 } // namespace Ocean
 
 #endif // META_OCEAN_MATH_CYLINDER_3_H
-

impl/ocean/test/testmath/TestCylinder3.cpp

@@ -190,7 +190,7 @@ bool TestCylinder3::testNearestIntersection(const double testDuration)
 						const T a = projectedDirection.sqr();
 						const T b = T(2.0) * (projectedDirection * projectedOrigin);
 						const T c = projectedOrigin.sqr() - T(1.0);
-						if (EquationT<T>::solveQuadratic(a, b, c, minDistance, maxDistance))
+						if (NumericT<T>::isNotEqualEps(a) && EquationT<T>::solveQuadratic(a, b, c, minDistance, maxDistance))
 						{
 							if (minDistance < T(0.0))
 							{