# 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

HermiteCurve(void)
HermiteCurve(ParametricCurve const &pc)

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

int append_cv(int type, PN_stdfloat x, PN_stdfloat y, PN_stdfloat z)
int append_cv(int type, LVecBase3 const &v)

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 TypeHandle get_class_type(void)
LVecBase3 const &get_cv_in(int n) const
void get_cv_in(int n, LVecBase3 &v) const

Returns the in tangent of the given CV.

std::string get_cv_name(int n) const

Returns the name of the given CV, or NULL.

LVecBase3 const &get_cv_out(int n) const
void get_cv_out(int n, LVecBase3 &v) const

Returns the out tangent of the given CV.

LVecBase3 const &get_cv_point(int n) const
void get_cv_point(int n, LVecBase3 &v) const

Returns the position of the given CV.

PN_stdfloat get_cv_tstart(int n) const

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

int get_cv_type(int n) const

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

int get_num_cvs(void) const

Returns the number of CV’s in the curve.

int insert_cv(PN_stdfloat t)

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.

void remove_all_cvs(void)

Removes all CV’s from the curve.

bool remove_cv(int n)

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

bool set_cv_in(int n, PN_stdfloat x, PN_stdfloat y, PN_stdfloat z)
bool set_cv_in(int n, LVecBase3 const &v)

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

bool set_cv_name(int n, char const *name)

Changes the name associated with a particular CV.

bool set_cv_out(int n, PN_stdfloat x, PN_stdfloat y, PN_stdfloat z)
bool set_cv_out(int n, LVecBase3 const &v)

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

bool set_cv_point(int n, PN_stdfloat x, PN_stdfloat y, PN_stdfloat z)
bool set_cv_point(int n, LVecBase3 const &v)

Changes the given CV’s position.

bool set_cv_tstart(int n, PN_stdfloat tstart)

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

bool set_cv_type(int n, int type)

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.

void write_cv(std::ostream &out, int n) const