Returns a derivative vector for a given point on a curve. Only first and second derivatives may be computed. The derivative vector is a function of the underlying mathematical representation of the curve. It is generally better to use the curveVector() function, which yields unit vectors and is a pure geometric value, independent of mathematical representation.
curveDerivative ( curve As Part, _
p1 As Point, _
n As Integer) As Vector
| Argument | Type | Description |
|---|---|---|
| Curve | part | The curve whose derivative is required. Must be a kind of curveMixin. |
| p1 | point | The point on the curve at which derivatives are to be computed. The point must be on the curve. |
| n | integer | The derivative required. Use 1 for first derivative, 2 for second. Values higher than these will return the second derivative. Zero will return the "position vector" - the coordinates of the point given, but as a Vector, not a Point. |
Intent >curveDerivative(Arc_1, Arc_1.midPoint, 1) --> Vector_(0.0, -5.0, 0.0, WorldFrame())
The tangent direction. Note that the magnitude is not 1.
Intent >curveDerivative(Arc_1, Arc_1.midPoint, 2) --> Vector_(5.0, 0.0, 0.0, WorldFrame())
The second derivative. Note that this is NOT the same as the normal to the curve, which is always perpendicular to the tangent. However, for an Arc, it is perpendicular.