# RopeNode¶

class RopeNode

Bases: PandaNode

This class draws a visible representation of the NURBS curve stored in its NurbsCurveEvaluator. It automatically recomputes the curve every frame.

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 diagram

enum NormalMode
enumerator NM_none = 0

Don’t generate normals.

enumerator NM_vertex = 1

enum RenderMode
enumerator RM_thread = 0

Render the rope as a one-pixel thread using a linestrip.

enumerator RM_tape = 1

Render the rope as a triangle strip oriented to be perpendicular to the tube_up vector.

enumerator RM_billboard = 2

Render the rope as a triangle strip oriented to be perpendicular to the view vector.

enumerator RM_tube = 3

Render the rope as a hollow tube extruded along its length.

enum UVMode
enumerator UV_none = 0

Don’t generate UV’s along the curve.

enumerator UV_parametric = 1

Generate UV’s based on the parametric coordinates along the curve.

enumerator UV_distance = 2

Generate UV’s in proportion to spatial distance along the curve, by using the distance function to compute the length of each segment.

enumerator UV_distance2 = 3

As above, but don’t bother to take the square root of each segment. The distance is then in proportion to the sum-of-squares of the segments along the rope. If the segments are similar in length, this approximates the proportion of UV_distance while avoiding hundreds of square root operations.

explicit RopeNode(std::string const &name)
void clear_matrix(void)

Resets the node’s matrix to identity. See set_matrix().

static TypeHandle get_class_type(void)
NurbsCurveEvaluator *get_curve(void) const

Returns the curve represented by the RopeNode.

LMatrix4 const &get_matrix(void) const

Returns the optional matrix which is used to transform each control vertex after it has been transformed into the RopeNode’s coordinate space, but before the polygon vertices are generated.

NormalMode get_normal_mode(void) const

Returns the kind of normals to generate for the rope. This is only applicable when the RenderMode is set to RM_tube.

int get_num_slices(void) const

Returns the number of radial subdivisions to make if RenderMode is RM_tube. It is ignored in the other render modes. See set_num_slices().

int get_num_subdiv(void) const

Returns the number of subdivisions per cubic segment to draw. See set_num_subdiv().

RenderMode get_render_mode(void) const

Returns the method used to render the rope. See set_render_mode().

PN_stdfloat get_thickness(void) const

Returns the thickness of the rope. See set_thickness().

LVector3 const &get_tube_up(void) const

Returns the normal vector used to control the “top” of the curve, when RenderMode is RM_tube. See set_tube_up().

bool get_use_vertex_color(void) const

Returns the “use vertex color” flag. See set_use_vertex_color().

bool get_use_vertex_thickness(void) const

Returns the “use vertex thickness” flag. See set_use_vertex_thickness().

bool get_uv_direction(void) const

Returns true if the rope runs down the U coordinate of the texture, or false if it runs down the V coordinate.

UVMode get_uv_mode(void) const

Returns the algorithm to use to generate UV’s for the rope.

PN_stdfloat get_uv_scale(void) const

Returns the scaling factor to apply to generated UV’s for the rope.

int get_vertex_color_dimension(void)

Returns the numeric extended dimension in which the color components should be found. See NurbsCurveEvaluator::set_extended_vertex().

The color components will be expected at (n, n + 1, n + 2, n + 3).

int get_vertex_thickness_dimension(void)

Returns the numeric extended dimension in which the thickness component should be found. See NurbsCurveEvaluator::set_extended_vertex().

bool has_matrix(void) const

Returns true if the node has a matrix set, false otherwise. See set_matrix().

void reset_bound(NodePath const &rel_to)

Recomputes the bounding volume. This is normally called automatically, but it must occasionally be called explicitly when the curve has changed properties outside of this node’s knowledge.

void set_curve(NurbsCurveEvaluator *curve)

Sets the particular curve represented by the RopeNode.

void set_matrix(LMatrix4 const &matrix)

Specifies an optional matrix which is used to transform each control vertex after it has been transformed into the RopeNode’s coordinate space, but before the polygon vertices are generated.

void set_normal_mode(RopeNode::NormalMode normal_mode)

Specifies the kind of normals to generate for the rope. This is only applicable when the RenderMode is set to RM_tube; in the other render modes, normals are never generated.

void set_num_slices(int num_slices)

Specifies the number of radial subdivisions to make if RenderMode is RM_tube. It is ignored in the other render modes.

Increasing this number increases the roundness of a cross-section of the tube. The minimum value for a dimensional tube is 3; setting it to 2 will get you a thin piece of tape (which is similar to RM_billboard, except it won’t rotate to face the camera).

void set_num_subdiv(int num_subdiv)

Specifies the number of subdivisions per cubic segment (that is, per unique knot value) to draw in a fixed uniform tesselation of the curve.

void set_render_mode(RopeNode::RenderMode render_mode)

Specifies the method used to render the rope. The simplest is RM_thread, which just draws a one-pixel line segment.

void set_thickness(PN_stdfloat thickness)

Specifies the thickness of the rope, in pixels or in spatial units, depending on the render mode. See set_render_mode().

The thickness may also be specified on a per-vertex basis. See set_use_vertex_thickness().

void set_tube_up(LVector3 const &tube_up)

Specifies a normal vector, generally perpendicular to the main axis of the starting point of the curve, that controls the “top” of the curve, when RenderMode is RM_tube. This is used to orient the vertices that make up the tube. If this vector is too nearly parallel with the starting direction of the curve, there may be a tendency for the whole tube to gimble-lock around its primary axis.

void set_use_vertex_color(bool flag)

Sets the “use vertex color” flag. When this is true, the R, G, B, A vertex color is assumed to be stored as the dimensions n + 0, n + 1, n + 2, n + 3, respectively, of the extended vertex values, where n is the value returned by get_vertex_color_dimension(). Use NurbsCurveEvaluator::set_extended_vertex() to set these values.

void set_use_vertex_thickness(bool flag)

Sets the “use vertex thickness” flag. When this is true, the vertex thickness is assumed to be stored as the dimension get_vertex_thickness_dimension(), of the extended vertex values. Use NurbsCurveEvaluator::set_extended_vertex() to set these values.

In this mode, the overall thickness is also applied as a scale to the vertex thickness. Not all render modes support vertex thickness.

void set_uv_direction(bool u_dominant)

Specify true to vary the U coordinate down the length of the rope, or false to vary the V coordinate.

void set_uv_mode(RopeNode::UVMode uv_mode)

Specifies the algorithm to use to generate UV’s for the rope.

void set_uv_scale(PN_stdfloat scale)

Specifies an additional scaling factor to apply to generated UV’s along the rope. This scale factor is applied in whichever direction is along the rope, as specified by set_uv_direction().