# HermiteCurve¶

```from panda3d.core import HermiteCurve
```
class `HermiteCurve`

Bases: `PiecewiseCurve`

A parametric curve defined by a sequence of control vertices, each with an in and out tangent.

This class is actually implemented as a `PiecewiseCurve` made up of several `CubicCurvesegs`, each of which is created using the hermite_basis() method. The HermiteCurve class itself keeps its own list of the CV’s that are used to define the curve (since the `CubicCurveseg` class doesn’t retain these).

Inheritance diagram

`__init__`()
`__init__`(pc: ParametricCurve)

Constructs a Hermite from the indicated (possibly non-hermite) curve.

`appendCv`(type: int, v: LVecBase3)int
`appendCv`(type: int, x: float, y: float, z: float)int

Adds a new CV to the end of the curve. The new CV is given initial in/out tangents of 0. The return value is the index of the new CV.

static `getClassType`()TypeHandle
`getCvIn`(n: int)LVecBase3

Returns the in tangent of the given CV.

`getCvIn`(n: int, v: LVecBase3)
`getCvName`(n: int)str

Returns the name of the given CV, or NULL.

`getCvOut`(n: int)LVecBase3

Returns the out tangent of the given CV.

`getCvOut`(n: int, v: LVecBase3)
`getCvPoint`(n: int)LVecBase3

Returns the position of the given CV.

`getCvPoint`(n: int, v: LVecBase3)
`getCvTstart`(n: int)float

Returns the starting point in parametric space of the given CV.

`getCvType`(n: int)int

Returns the given CV’s continuity type, HC_CUT, HC_FREE, HC_G1, or HC_SMOOTH, or 0 if there is no such CV.

`getNumCvs`()int

Returns the number of CV’s in the curve.

`insertCv`(t: float)int

Inserts a new CV at the given parametric point along the curve. If this parametric point is already on the curve, the CV is assigned an index between its two neighbors and the indices of all following CV’s are incremented by 1; its in and out tangents are chosen to keep the curve consistent. If the new parametric point is beyond the end of the existing curve, the curve is extended to meet it and the new CV’s position, in tangent, and out tangent are set to zero.

The index number of the new CV is returned.

`removeAllCvs`()

Removes all CV’s from the curve.

`removeCv`(n: int)bool

Removes the given CV from the curve. Returns true if the CV existed, false otherwise.

`setCvIn`(n: int, v: LVecBase3)bool
`setCvIn`(n: int, x: float, y: float, z: float)bool

Changes the given CV’s in tangent. Depending on the continuity type, this may also adjust the out tangent.

`setCvName`(n: int, name: str)bool

Changes the name associated with a particular CV.

`setCvOut`(n: int, v: LVecBase3)bool
`setCvOut`(n: int, x: float, y: float, z: float)bool

Changes the given CV’s out tangent. Depending on the continuity type, this may also adjust the in tangent.

`setCvPoint`(n: int, v: LVecBase3)bool
`setCvPoint`(n: int, x: float, y: float, z: float)bool

Changes the given CV’s position.

`setCvTstart`(n: int, tstart: float)bool

Changes the given CV’s parametric starting time. This may affect the shape of the curve.

`setCvType`(n: int, type: int)bool

Changes the given CV’s continuity type. Legal values are HC_CUT, HC_FREE, HC_G1, or HC_SMOOTH.

Other than HC_CUT, these have no effect on the actual curve; it remains up to user software to impose the constraints these imply.

HC_CUT implies a disconnection of the curve; HC_FREE imposes no constraints on the tangents; HC_G1 forces the tangents to be collinear, and HC_SMOOTH forces the tangents to be identical. Setting type type to HC_G1 or HC_SMOOTH may adjust the out tangent to match the in tangent.

`writeCv`(out: ostream, n: int)