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Curve

Curve nodes: Read, Sample, Write, Operations, Primitives, Topology.

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Read

Add - Curve - Read

Here you find curve related nodes.

Curve Handle Positions

Get the position of the left or right handle of a curve point.

Entry	What it does
Inputs	Relative: Output the handle positions relative to the corresponding control point instead of the local space of the geometry.
Outputs	Left: The left handle of the curve point. · Right: The right handle of the curve point.

Cuve Length

Retreives the length of all splines added together.

Entry	What it does
Inputs	Curve: The input curve.
Outputs	Length: The length of the curve.

Curve Tangent

Retreive the tangent direction of a curve. The output values are normalized vectors.

Note that for NURBS and Bézier spline curves the value retrieved from this node is the value at every control point, which may not correspond to the visible evaluated points. For NURBS splines the difference may be even more pronounced and the result may not be as expected. A Resample Curve Node node can be used to create a poly spline, where there is a control point for every evaluated point.

Outputs

Factor

The vector of the tangent.

Curve Tilt

Outputs the angle used to turn the curve normal around the direction of the curve tangent in its evaluated points.

The output is per control point. For NURBS and Bézier splines, the values will be interpolated to the final evaluated points.

Outputs

Tilt

The tilt angle for the normal in radians.

Endpoint Selection

The Endpoint Selection node allows for the Selection of an aribitrary
number of endpoints from each spline in a curve. The start and end
inputs are evaluated on the spline domain. The result is outputted
as a boolean field on the point domain.

Entry	What it does
Input	Start Size: The start point of the spline. · End Size: The end point of the spline.
Outputs	Selection: Selection output.

Handle Type Selection

Creates a selection based on the handle types of the control points.

Properties

Left / Right

Wether to check for the type of handles.

Handle Type

What handle type to compare.

Output

Selection

The selection.

Is Spline Cyclic

Retreive if the curve is set to cyclic.

Outputs

Cyclic

If the spline is cyclic or not.

Spline Length

Retreive the total length of each spline in a curve.

Outputs

Entry	What it does
Length	The length of each spline in the curve.
Point Count	Integer Field input of the number of control points on each spline in the spline domain. Or in the point domain, it is the number of points on the spline that contains the given control point.

Spline Parameter

The Curve Parameter node outputs how far along each spline a control point is, with a value between zero and one. The output is different from dividing the index by the total number of control points, because the control points might not be equally spaced along the curve.

The first value is zero, so the output corresponds to the length at the control point rather than including the length of the following segment.

When used on the spline domain, the node outputs the portion of the total length of the curve (including all splines) has been traversed at the start of each spline. The order of the curve’s splines is visible in the Spreadsheet Editor.

Outputs

Entry	What it does
Factor	The factor of the curve.
Length	The length of the curve.
Index	The index of the curve.

Spline Resolution

Retreive the curve resolution. Means the number of spline points.

Outputs

Resolution

The spline resolution.

Sample

Add - Curve - Sample

Here you find curve related nodes.

Sample Curve

Calculates a point on a curve at a certain distance from the start of the curve, specified by the length or factor inputs. It also outputs data retrieved from that position on the curve.

The sampled values are linearly interpolated from the values at the evaluated curve points at each side of the sampled point.

In case that the curve contains multiple splines, the sample position is found based on the total accumulated length, including the lengths of all previous splines. The order of the splines is the same order as displayed in the Spreadsheet Editor.

Input

Entry	What it does
Curve	The input geometry.
Value	Input Value.
Mode Factor	Factor: The resample amount with method Factor. · Curve Index: The curve index.
Mode Factor	Factor: The resample amount with method Factor.
Length	The resample amount with method Length.

Properties

Data Type

What data to calculate.

Entry	What it does
Sample Curve Mode	How to calculate the curve. By a factor, or by its length.
All Curves	Sample lengths based on the length of all curves.

Output

Entry	What it does
Value	Output Value.
Position	The position at the sample along the spline.
Tangent	The normalized curve tangent at the sample.
Normal	The normalized curve normal at the sample.

Write

Add - Curve - Write

Here you find curve related nodes.

Set Curve Normal

Set the evaluation mode for curve normals.

Input

Entry	What it does
Curve	The input curve.
Selection	A selection of the input curve.

Mode

The evaluation mode for the curve normals.

Outputs

Curve

The curve output.

Set Curve Radius

Set the curve radius.

Entry	What it does
Input	Geometry: The input curve. · Selection: A selection of the input curve. · Radius: The radius to set.
Outputs	Geometry: Standard geometry output.

Set Curve Tilt

Controls the tilt angle at each curve control point.

Entry	What it does
Input	Geometry: The input curve. · Selection: Whether or not to change the value on each control point. True values mean the value will be changed, false values mean the value will remain the same. · Tilt: The tilt rotation.
Outputs	Curve: Standard geometry output.

Set Handle Positions

Set the handle positions of bezier curves

Entry	What it does
Input	Geometry: The input curve. · Selection: A selection of the input curve. · Position: The position of the handle. · Offset: A vector 3 offset for the handles.
Properties	Mode: Left or right handles.
Outputs	Geometry: Standard geometry output.

Set Handle Type

Sets a handle type for the curve points of a bezier curve. Handle types determines how the interpolation before and after the curve point happens.

Input

Entry	What it does
Curve	The input curve.
Selection	A selection of the input curve.

Properties

Mode

Left or right handles.

Handle Type

The different available handle types.

Free

The handles can be adjusted individually.

Auto

The left and the right handle will always point to each other. The length of the handles will start in equal size.

Vector

The handles can be adjusted individually.

Aligned

The left and the right handle will always point to each other.

Output

Curve

Standard geometry output.

Set Spline cyclic

Sets the spline cyclic. Means looping.

Entry	What it does
Input	Geometry: The input curve. · Selection: A selection of the input curve. · Cyclic: Cyclic or not
Outputs	Geometry: Standard geometry output.

Set Spline Resolution

Sets the resolution of the spline. Means how many evaluated points should be generated on the curve for each control point.

Entry	What it does
Input	Geometry: The input curve. · Selection: A selection of the input curve. · Resolution: The resolution of the spline.
Outputs	Geometry: Standard geometry output.

Set Spline Type

Change the curve spline type.

Input

Entry	What it does
Curve	The input curve.
Selection	A selection of the input curve.

Properties

Spline Type

The spline type to set the curve to.

Note that when converting from a NURBS spline to a Bézier spline, at least six points are needed. When the number of points is not a multiple of three a full conversion is not possible and the spline has to be truncated.

Output

Curve

Standard geometry output.

Operations

Add - Curve

Here you find curve related nodes.

Cuve to Mesh

Converts a curve object to a mesh object. Optionally, a profile curve can be provided to give the curve a custom shape.

Entry	What it does
Inputs	Curve: The input curve. · Profile Curve: If a profile curve is provided, it will be extruded along all splines. Otherwise the generated mesh will just be a chain of edges. · Scale: Scale of the profile at each point. · Fill Caps: For cyclic profile curve. Fill the ends of the generated mesh for each spline combination with an N-gon. The resulting mesh is Manifold, the two new faces for each spline are simply connected to existing edges.
Outputs	Mesh: Standard mesh output.

Entry

What it does

Inputs

Curve: The input curve. · Profile Curve: If a profile curve is provided, it will be extruded along all splines. Otherwise the generated mesh will just be a chain of edges. · Scale: Scale of the profile at each point. · Fill Caps: For cyclic profile curve. Fill the ends of the generated mesh for each spline combination with an N-gon. The resulting mesh is Manifold, the two new faces for each spline are simply connected to existing edges.

Outputs

Mesh: Standard mesh output.

Cuve to Points

Converts a curve object to a Point cloud.

Inputs

Curve

The input curve.

Properties

Mode

How to generate points from the input curve.

Evaluated

Create points from the evaluation points of the curve. This is based on the resolution attribute for nurbs and bezier splines.

Count

Sample each spline by evenly distributing the specified number of points along the spline.

Count Input

The number of points to distribute along the spline.

Length

Sample each spline by splitting the spline into segments by the specified length.

Length Input

The length of the single segments.

Outputs

Entry	What it does
Point	Generated point cloud.
Tangent	The normalized curve tangent at the sampled position, or the direct evaluated normal in Evaluated mode.
Normal	The normal value from the evaluated curve at each result point. This is the same value from the Normal Node at those positions.
Rotation	—

Cuves to Grease Pencil

Converts a curve object to a mesh object. Optionally, a profile curve can be provided to give the curve a custom shape.

Entry	What it does
Inputs	Curves: The input curves. · Selection: A selection of the curve · Instances as Layers: Create separate layers for each instance.
Outputs	Grease Pencil: Standard output. The Euler rotation build from the Tangent and Normal outputs.

Deform Curves on Surface

Curves that are attached to a surface can follow the surface at modification.

Entry	What it does
Inputs	Curves: The input curve.
Outputs	Curves: The output curve.

Fill Curve

Fills the curve with mesh geometry. The mesh is only generated flat with a local Z of 0.

Inputs

Entry	What it does
Curve	The input curve.
Group Input	An index used to rgoup curves together. Filling is done separately for each group.

Mode

Triangles or N-gons

Fill the curve with either triangles, or use N-Gon geometry.

Outputs

Mesh

The output as mesh.

Fillet Curve

The Fillet Curve rounds corners on curve control points, similar to the effect of the Bevel Modifier on a 2D mesh.

A key difference is that the rounded portions created by the Fillet Curve node are always portions of a circle.

Input

Entry	What it does
Curve	The input curve.
Count	Polymode. Define the number of vertices that are created.
Radius	The radius of the arc
Limit Radius	Prevent overlapping when the defined radius exceeds the maximum possible radius for a given point.

Mode

Entry	What it does
Bezier	Creates a circular arc at vertices by changing handle lengths (applicable only for Bezier splines).
Poly	Creates a circular arc by creating vertices (as many as defined by the Count fields input) along the arc (applicable for all spline types).

Outputs

Curve

Standard geometry input with a curve component.

Interpolate Curves

Generates new curve parts by interpolating between existing curves.

Input

Entry	What it does
Guide Curves	The base curves to interpolate from.
Guide Up	An optional up vector that is typically a surface normal. Providing this up vector can improve the quality of the interpolation. This up direction can be retrieved with a combination of the Sample UV Surface Node using the same geometry that the points were distributed on, and the Normal Node.
Guide Group ID	Splits guides into separate groups. New curves interpolate existing curves from a single group.
Points	The positions of the first root control points of the newly generated interpolated curves.
Points Up	Optional up vector that is typically a surface normal.
Point Group ID	The curve group to interpolate in.
Max Neighbor	Maximum amount of close guide curves that are taken into account for interpolation.

Outputs

Entry	What it does
Curves	The new curve.
Closest Index	Index of the closest guide curve for each generated curve. Note that internally this node mixes the data from multiple guide curves, with the maximum number of sources depending on the Max Neighbor input. This output is only the index of the curve with the largest weight.
Closest Weight	Weight of the closest guide curve for each generated curve.

Resample curve

Creates a poly spline for each input spline. In the Count and Length modes, the control points of the new poly splines will have uniform spacing.

Input

Entry	What it does
Curve	The input geometry.
Selection	A selection of the input geometry
Length	The approximate length between the control points of the new splines.

Mode

The resample mode.

Entry	What it does
Evaluated	Use the resolution attribute for spline and bezier curves.
Count	Use the count of the curve points.
Length	Use the length of the curve.

Count

The number of control points on the new splines.

Output

Curve

Standard geometry output.

Reverse Curve

Reverses the direction of the spline. The start point becomes the end point and vice versa. The shape of the spline is not modified.

Entry	What it does
Inputs	Curve: The input curve. · Selection: An optional selection attribute to determine which part of the spline should be reversed.
Outputs	Curve: Standard geometry output.

Subdivide Curve

Subdivides the curve. The shape is not changed.

Entry	What it does
Inputs	Geometry: The input curve. · Cuts: The number of cuts per segment.
Outputs	Geometry: Standard geometry output.

Trim Curve

The Curve Trim node shortens each spline in the curve by removing sections at the start and end of each spline.

Bézier splines will still output as Bézier splines. The first and last control point and its handles will be moved as necessary to preserve the shape. But NURBS splines will be transformed into poly splines in order to be trimmed.

Cyclic splines are currently not supported.

Note that if the Start input is larger than the End, then the resulting spline will have a single point, located at the sample location of the Start value.

Inputs

Entry	What it does
Curve	The input curve.
Selection	A selection of the curve.
Start	The start point of the spline, as a factor.
End	The end point of the spline, as a factor.

Properties

Mode

How to find endpoint positions for the trimmed spline.

Entry	What it does
Factor	The endpoint positions of each spline’s length is determined by a factor. The input values should be between 0 or 1.
Length	The endpoint positions of each spline is determined by a length from the start of each spline. The input values should be between 0 and the length of the splines.

Outputs

Curve

Standard geometry output.

Primitives

Add curve primitives in different shapes.

Arc

Adds a bezier curve segment in the shape of an arc

Inputs

Entry	What it does
Resolution	The number of edges on the curve.
in Radius mode	Radius: Just Radius mode. The radius of the arc. · Start Angle: Just Radius mode. The start angle of the arc. · Sweep Angle: Just Radius mode. The sweep angle of the arc.
In Points Mode	Start: The start point vector of the ark. · Middle: The middle point vector of the ark. · End: The end point vector of the ark. · Offset Angle: The offset angle of the ark.
Connect Center	Connect the start and endpoins to the center.
Invert Arc	Inverts the arc.

Properties

Mode

Point or Radius mode.

Radius mode (default): Generates a fixed radius arc on XY plane with controls for Angle, Sweep and Invert.

Points mode: Generates a three point curve arc from Start to End via Middle with an Angle Offset and option to invert the arc. There are also outputs for arc center, radius and normal direction relative to the Z-axis.

Outputs

Entry	What it does
Curve	Curve output.
In Points Mode	Center: The center vector of the arc. · Normal: The normal of the arc. · Radius: The radius of the arc.

Bezier Segment

Adds a bezier curve segment.

Inputs

Entry	What it does
Resolution	The number of edges on the curve.
Start, End	Positions of the start and end control point of the curve.
Start Handle, End Handle	Positions of the handles used to define the shape of the curve.

Properties

Mode

Entry	What it does
Position	The handle inputs are the absolute positions of the handles in 3D space.
Offset	The handle positions are relative to the control point on the curve. The handle inputs give the offset from the control points.

Outputs

Curve

Bezier spline generated from the inputs.

Curve Circle

Adds a curve in circle shape.

Inputs

Resolution

Number of edges on the circle.

Radius

The radius of the circle.

Point 1, Point 2, Point 3

Appears when you change the method to Points. Defines three points on the circle. The order of the points determines the direction (clockwise or counterclockwise) of the circle.

Note that because of the finite resolution, the three points do not necessarily lie on the generated curve.

Properties

Mode

Entry	What it does
Points	The position and radius of the circle is defined by three points. The center of the circle is also given as an output. If the three points lie on one line, no geometry is generated.
Radius	The circle is defined by the radius.

Outputs

Entry	What it does
Curve	Poly spline generated from the inputs.
Center	Appears when you change the method to Points. The center of the circle defined by the three points.

Curve Line

Adds a curve in the shape of a straight line.

Properties

Points

Calculates the curve by a start and end point.

Entry	What it does
Start	The start point of the curve.
End	The end point of the curve.

Direction

Calculates the curve by a start point, a direction vector and the length of the curve.

Entry	What it does
Start	The start point of the curve.
Direction	The direction vector.
Length	The length of the curve.

Outputs

Curve

The created curve.

Spiral

Adds a curve in spiral shape. By default the spiral twists clockwise.

Entry	What it does
Inputs	Resolution: Number of edges for each full rotation. · Rotations: Number of times the spiral makes a full rotation. · Start Radius, End Radius: Radius of the start point and end point of the spiral. The radius of the spiral changes linearly between the two values over the whole spiral. · Height: Height of the spiral. · Reverse: Boolean value that changes the direction from clockwise to counterclockwise when turned on.
Outputs	Curve: Poly spline generated from the inputs.

Entry

What it does

Inputs

Resolution: Number of edges for each full rotation. · Rotations: Number of times the spiral makes a full rotation. · Start Radius, End Radius: Radius of the start point and end point of the spiral. The radius of the spiral changes linearly between the two values over the whole spiral. · Height: Height of the spiral. · Reverse: Boolean value that changes the direction from clockwise to counterclockwise when turned on.

Outputs

Curve: Poly spline generated from the inputs.

Quadratic Bezier

Adds a curve from the given control points. The generated shape is a parabola.

Entry	What it does
Inputs	Resolution: The number of edges on the curve. · Start, Middle, End: Positions of the three control points. The generated curve passes through the two end points, and is tangent to the lines between the middle point and the two end points.
Outputs	Curve: Poly spline generated from the inputs.

Quadrilateral

Adds a curve in different geometric shapes.

Note that the names does not necessarily fit to the generated geometry.

Input

The input nodes may vary. See Properties.

Properties

Mode

Rectangle

creates a straight line in y direction.

Width

The length of the straight line.

Parallelogram

Creates a straight line that is adjustable in x and y direction.

Entry	What it does
Height	The height of the line.
Offset	The width of the line.

Trapezoid

Entry	What it does
Height	The height of the trapez.
Bottom Width	The width of the bottom line of the trapez.
Top Width	The width of the top line of the trapez.
Offset	The offset of the top line of the trapez.

Kite

creates a straight line in y direction. The curve end points are separately adjustable

Entry	What it does
Bottom Height	The length of the bottom part of the line.
Top Height	The length of the top part of the line.

Points

Creates a rectangle. Each point of the rectangle is independantly adjustable in x, y and z position.

Star

Adds a curve in star shape.

This is done by connecting alternating points of two circles. The points on the inner circle are offset by a rotation so that they lie in between the points on the outer circle. This offset can be changed with the twist input.

Entry	What it does
Inputs	Points: Number of points on each of the circles. · Inner Radius, Outer Radius: Radii of the two circles. The inner radius can be bigger than the outer radius. · Twist: Angle offset of the inner circle. The twist value rotates the points on the circle corresponding with the inner radius counterclockwise by the given angle.
Outputs	Curve: Poly spline generated from the inputs.

Topology

Curve topology related nodes.

Curve of Point

Retrieve the curve of which the control point is part of.

Entry	What it does
Inputs	Point Index: The point index of the curve. · Offset: Offset of the point index.
Outputs	Curve Index: The curve of which the control point is part of. · Index in Curve: How far along the curve the control point is.

Offset Points in Curve

Offset a control point index in the curve.

Entry	What it does
Inputs	Point Index: The point index of the curve. · Offset: Offset of the point index.
Outputs	Is Valid Offset: Outputs true if the evaluated controlpoint plus the offset is a valid index. · Point Index: The index of the control point plus the offset.

Points of Curve

Retreive a point index within a curve.

Entry	What it does
Inputs	Curve Index: The curve to retreive the data from · Weights: Values to sort the curve points. · Sort Index: The point to output.
Outputs	Point Index: The output point. · Total: The number of points in the curve.

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