# NurbsCurveEvaluator

from pandac.PandaModules import NurbsCurveEvaluator

Class : NurbsCurveEvaluator
Description : This class is an abstraction for evaluating NURBS curves. It accepts an array of vertices, each of which may be in a different coordinate space (as defined by a NodePath), as well as an optional knot vector.
This is not related to NurbsCurve, CubicCurveseg or any of the ParametricCurve-derived objects in this module. It is a completely parallel implementation of NURBS curves, and will probably eventually replace the whole ParametricCurve class hierarchy.

## Inheritance:

NurbsCurveEvaluator: ReferenceCount
ReferenceCount:

## Methods of NurbsCurveEvaluator:

evaluate
getExtendedVertex
getKnot
getNumKnots
getNumSegments
getNumVertices
getOrder
getVertex
getVertexSpace
normalizeKnots
output
reset
setExtendedVertex
setExtendedVertices
setKnot
setOrder
setVertex
setVertexSpace

## Methods of ReferenceCount:

getClassType
getRefCount
ref
testRefCountIntegrity
testRefCountNonzero
unref

evaluate PointerTo< NurbsCurveResult > NurbsCurveEvaluator::evaluate(NodePath const &rel_to = ((()))) const; Description: Returns a NurbsCurveResult object that represents the result of applying the knots to all of the current values of the vertices, transformed into the indicated coordinate space. Description: Returns a NurbsCurveResult object that represents the result of applying the knots to all of the current values of the vertices, transformed into the indicated coordinate space, and then further transformed by the indicated matrix.

getExtendedVertex float NurbsCurveEvaluator::get_extended_vertex(int i, int d) const; Description: Returns an n-dimensional vertex value. See set_extended_vertex(). This returns the value set for the indicated dimension, or 0.0 if nothing has been set.

getKnot float NurbsCurveEvaluator::get_knot(int i) const; Description: Returns the value of the nth knot.

getNumKnots int NurbsCurveEvaluator::get_num_knots(void) const; Description: Returns the number of knot values in the curve. This is based on the number of vertices and the order.

getNumSegments int NurbsCurveEvaluator::get_num_segments(void) const; Description: Returns the number of piecewise continuous segments in the curve. This is based on the knot vector.

getNumVertices int NurbsCurveEvaluator::get_num_vertices(void) const; Description: Returns the number of control vertices in the curve. This is the number passed to the last call to reset().

getOrder int NurbsCurveEvaluator::get_order(void) const; Description: Returns the order of the curve as set by a previous call to set_order().

getVertex LVecBase4f const &NurbsCurveEvaluator::get_vertex(int i) const; Description: Returns the nth control vertex of the curve, relative to its indicated coordinate space. Description: Returns the nth control vertex of the curve, relative to the given coordinate space.

getVertexSpace NodePath NurbsCurveEvaluator::get_vertex_space(int i, NodePath const &rel_to) const; Description: Returns the coordinate space of the nth control vertex of the curve, expressed as a NodePath.

normalizeKnots void NurbsCurveEvaluator::normalize_knots(void); Description: Normalizes the knot sequence so that the parametric range of the curve is 0 .. 1.

output void NurbsCurveEvaluator::output(ostream &out) const; Description:

reset void NurbsCurveEvaluator::reset(int num_vertices); Description: Resets all the vertices and knots to their default values, and sets the curve up with the indicated number of vertices. You must then call set_vertex() repeatedly to fill in all of the vertex values appropriately.

setExtendedVertex void NurbsCurveEvaluator::set_extended_vertex(int i, int d, float value); Description: Sets an n-dimensional vertex value. This allows definition of a NURBS surface or curve in a sparse n-dimensional space, typically used for associating additional properties (like color or joint membership) with each vertex of a surface. The value d is an arbitrary integer value and specifies the dimension of question for this particular vertex. Any number of dimensions may be specified, and they need not be consecutive. If a value for a given dimension is not specified, is it implicitly 0.0. The value is implicitly scaled by the homogenous weight value--that is, the fourth component of the value passed to set_vertex(). This means the ordinary vertex must be set first, before the extended vertices can be set.

setExtendedVertices void NurbsCurveEvaluator::set_extended_vertices(int i, int d, void *values[](unsigned int size), int num_values); Description: Simultaneously sets several extended values in the slots d through (d + num_values - 1) from the num_values elements of the indicated array. This is equivalent to calling set_extended_vertex() num_values times. See set_extended_vertex().

setKnot void NurbsCurveEvaluator::set_knot(int i, float knot); Description: Sets the value of the nth knot. Each knot value should be greater than or equal to the preceding value. If no knot values are set, a default knot vector is supplied.

setOrder void NurbsCurveEvaluator::set_order(int order); Filename: nurbsCurveEvaluator.I Created by: drose (05Dec02) PANDA 3D SOFTWARE Copyright (c) 2001 - 2004, Disney Enterprises, Inc. All rights reserved All use of this software is subject to the terms of the Panda 3d Software license. You should have received a copy of this license along with this source code; you will also find a current copy of the license at http://etc.cmu.edu/panda3d/docs/license/ . To contact the maintainers of this program write to panda3d-general@lists.sourceforge.net . Description: Sets the order of the curve. This resets the knot vector to the default knot vector for the number of vertices. The order must be 1, 2, 3, or 4, and the value is one more than the degree of the curve.

setVertex void NurbsCurveEvaluator::set_vertex(int i, LVecBase4f const &vertex); Description: Sets the nth control vertex of the curve, as a vertex in 4-d homogeneous space. In this form, the first three components of the vertex should already have been scaled by the fourth component, which is the homogeneous weight. Description: Sets the nth control vertex of the curve. This flavor sets the vertex as a 3-d coordinate and a weight; the 3-d coordinate values are implicitly scaled up by the weight factor.

setVertexSpace void NurbsCurveEvaluator::set_vertex_space(int i, NodePath const &space); Description: Sets the coordinate space of the nth control vertex. If this is not specified, or is set to an empty NodePath, the nth control vertex is deemed to be in the coordinate space passed to evaluate(). This specifies the space as a fixed NodePath, which is always the same NodePath. Also see setting the space as a path string, which can specify a different NodePath for different instances of the curve. Description: Sets the coordinate space of the nth control vertex. If this is not specified, or is set to an empty string, the nth control vertex is deemed to be in the coordinate space passed to evaluate(). This specifies the space as a string, which describes the path to find the node relative to the rel_to NodePath when the curve is evaluated.

getClassType static TypeHandle ReferenceCount::get_class_type(void); Undocumented function.

getRefCount int ReferenceCount::get_ref_count(void) const; Description: Returns the current reference count.

ref void ReferenceCount::ref(void) const; Description: Explicitly increments the reference count. User code should avoid using ref() and unref() directly, which can result in missed reference counts. Instead, let a PointerTo object manage the reference counting automatically. This function is const, even though it changes the object, because generally fiddling with an object's reference count isn't considered part of fiddling with the object. An object might be const in other ways, but we still need to accurately count the number of references to it.

testRefCountIntegrity bool ReferenceCount::test_ref_count_integrity(void) const; Description: Does some easy checks to make sure that the reference count isn't completely bogus. Returns true if ok, false otherwise.

testRefCountNonzero bool ReferenceCount::test_ref_count_nonzero(void) const; Description: Does some easy checks to make sure that the reference count isn't zero, or completely bogus. Returns true if ok, false otherwise.

unref bool ReferenceCount::unref(void) const; Description: Explicitly decrements the reference count. Note that the object will not be implicitly deleted by unref() simply because the reference count drops to zero. (Having a member function delete itself is problematic; plus, we don't have a virtual destructor anyway.) However, see the helper function unref_delete(). User code should avoid using ref() and unref() directly, which can result in missed reference counts. Instead, let a PointerTo object manage the reference counting automatically. This function is const, even though it changes the object, because generally fiddling with an object's reference count isn't considered part of fiddling with the object. An object might be const in other ways, but we still need to accurately count the number of references to it. The return value is true if the new reference count is nonzero, false if it is zero.