How a curve bends at one place: the point, the unit tangent, the principal normal pointing to the
center of curvature, the binormal (tangent x normal), the curvature (1 over the radius), the
radius, the center of the circle that fits the curve there, and the torsion, positive where the
curve winds as a right-handed helix does. Where the curve runs straight, isStraight is true, the
curvature and torsion are 0, the radius is Infinity, the normal and binormal are zero vectors
and the center is the point itself.
How a curve bends at one place: the point, the unit tangent, the principal normal pointing to the center of curvature, the binormal (tangent x normal), the curvature (1 over the radius), the radius, the center of the circle that fits the curve there, and the torsion, positive where the curve winds as a right-handed helix does. Where the curve runs straight,
isStraightis true, the curvature and torsion are 0, the radius isInfinity, the normal and binormal are zero vectors and the center is the point itself.