# ParametricCurve

```from panda3d.core import ParametricCurve
```
class ParametricCurve

Bases:

Bases: `PandaNode`

A virtual base class for parametric curves. This encapsulates all curves in 3-d space defined for a single parameter t in the range [0,get_max_t()].

Inheritance diagram

adjust_point(t: float, px: float, py: float, pz: float) bool

Recomputes the curve such that it passes through the point (px, py, pz) at time t, but keeps the same tangent value at that point.

adjust_pt(t: float, px: float, py: float, pz: float, tx: float, ty: float, tz: float) bool

Recomputes the curve such that it passes through the point (px, py, pz) with the tangent (tx, ty, tz).

adjust_tangent(t: float, tx: float, ty: float, tz: float) bool

Recomputes the curve such that it has the tangent (tx, ty, tz) at time t, but keeps the same position at the point.

calc_length()

Approximates the length of the entire curve to within a few decimal places.

calc_length(from: float, to: float)

Approximates the length of the curve segment from parametric time ‘from’ to time ‘to’.

find_length(start_t: float, length_offset: float)

Returns the parametric value corresponding to the indicated distance along the curve from the starting parametric value.

This is the inverse of calc_length(): rather than determining the length along the curve between two parametric points, it determines the position in parametric time of a point n units along the curve.

The search distance must not be negative.

get_2ndtangent(t: float, tangent2: LVecBase3) bool
static get_class_type()
get_curve_type() int

Returns the flag indicating the use to which the curve is intended to be put.

get_max_t()

Returns the upper bound of t for the entire curve. The curve is defined in the range 0.0f <= t <= get_max_t(). This base class function always returns 1.0f; derived classes might override this to return something else.

get_num_dimensions() int

Returns the number of significant dimensions in the curve’s vertices, as set by a previous call to `set_num_dimensions()`. This is only a hint as to how the curve is intended to be used; the actual number of dimensions of any curve is always three.

get_point(t: float, point: LVecBase3) bool
get_pt(t: float, point: LVecBase3, tangent: LVecBase3) bool
get_tangent(t: float, tangent: LVecBase3) bool
is_valid() bool

Returns true if the curve is defined. This base class function always returns true; derived classes might override this to sometimes return false.

recompute() bool

Recalculates the curve, if necessary. Returns true if the resulting curve is valid, false otherwise.

set_curve_type(type: int)

Sets the flag indicating the use to which the curve is intended to be put. This flag is optional and only serves to provide a hint to the egg reader and writer code; it has no effect on the curve’s behavior.

Setting the curve type also sets the num_dimensions to 3 or 1 according to the type.

THis flag may have one of the values PCT_XYZ, PCT_HPR, or PCT_T.

set_num_dimensions(num: int)

Specifies the number of significant dimensions in the curve’s vertices. This should be one of 1, 2, or 3. Normally, XYZ and HPR curves have three dimensions; time curves should always have one dimension. This only serves as a hint to the mopath editor, and also controls how the curve is written out.

stitch(a: ParametricCurve, b: ParametricCurve) bool

Regenerates this curve as one long curve: the first curve connected end-to- end with the second one. Either a or b may be the same as ‘this’.

Returns true if successful, false on failure or if the curve type does not support stitching.

write_egg(filename: Filename, cs: CoordinateSystem) bool

Writes an egg description of the nurbs curve to the specified output file. Returns true if the file is successfully written.

write_egg(out: ostream, filename: Filename, cs: CoordinateSystem) bool

Writes an egg description of the nurbs curve to the specified output stream. Returns true if the file is successfully written.