Twist along Curve Field

Functionality

This node generates a vector field, which does a generic type of space transformation. It is similar to what “Bend Along Curve Field” node does, but rotation of space around the curve is controlled by user, not calculated by some algorithm. So with this node you can generate a field that does a combination of two transformations: 1) bending along some curve, and 2) arbitrary twisting around that curve.

Inputs

This node has the following inputs:

• Curve. The curve to bend and twist around. This input is mandatory.

• Matrices. This input is available and mandatory only when Input parameter is set to Matrices. This input should contain a list of matrices, that specify rotation of space around the curve. Locations of matrices define places on the curve where corresponding rotation should be done.

• Quaternions. This input is availale and mandatory only when Input parameter is set to Quaternions. This input should contain a lsit of quaternions, which define rotation of space around the curve. Locations of these rotations on the curve are defined by values in T/Length input.

• Vectors. This input is available and mandatory only when Input parameter is set to Track Vectors. This input should contain a list of vectors, which point in a direction to which tracking axis must be rotated. Locations of these rotations on the curve are defined by values in T/Length input.

• T/Length. This input is available and mandatory when Input parameter is set to Quaternions or Track Vectors. Values define places on the curve where corresponding rotations should be placed. If Parametrization parameter is set to Curve Parameter, then this input should contain curve T parameter values; otherwise, this input should contain arc length parameters (lengths from the beginning on the curve).

• LengthResolution. This input is available and mandatory only when Parametrization parameter is set to Curve Length. This defines the resolution used to calculate curve lengths. Higher values give more precision, but take more time to calculate. The default value is 50.

Parameters

This node has the following parameters:

• Input. This defines how rotations around the curve will be specified. The available options are:

  • Matrices. The user provides a list of matrices. Locations of matrices in 3D space define locations on the curve where rotations should be placed. One of matrix axes (called orientation axis, see Orientation parameter below) is supposed to be directed along the curve, but not necessarily precisely. Rotation of the matrix along orientation curve define the rotaiton of the space around the curve. Scale and skew components of matrices are ignored.

  • Quaternions. The user provides a list of quaternions, which define rotations around the curve. Places of these rotations along the curve are defined by values in T/Length input.

  • Track Vectors. The user provides a list of vectors, which define directions where “tracking axis” should look to. Rotations are always done around curve tangent vectors. The places on the curve where these rotations should be placed are defined by values in T/Length input.

  The default option is Matrices.

• Parametrization. This defines what type of curve parametrization should be used. This also defines the part of 3D space which will be bent and rotated around the curve. The available options are:

  • Curve Parameter. Original coordinates in 3D space along axis specified in Orientation parameter will be used as curve T parameters. So, for example, if curve domain is from 0 to 1, then the part of space which will be bent is from 0 to 1 along orientation axis.

  • Curve Length. Original coordinates in 3D space along orientation axis will be used as curve arc length parameters (length of parts of curve from beginning of the curve). So, for example, if curve length is 11.5, then the part of space to be bent will be from 0 to 11.5 along orientation axis.

  The default option is Curve Parameter.

• Orientation. This parameter defines which axis of original 3D space should be bent along the curve. The default value is Z.

• Track Axis. This parameter is only available when Input parameter is set to Track Vectors. This defines which axis of original 3D space should be looking along user-provided tracking vectors after rotations. Tracking axis must not coincide with orientation axis. The default option is X.

• Interpolation. This defines the type of interpolation between user-provided rotations of the space. The available options are Linear and Spline. The default option is Spline.

Outputs

This node has the following output:

• Field. The generated vector field.

Examples of Usage

Example nodes setup:

Result:

Same, but with Linear interpolation mode:

Example setup for Matrices input mode:

Result: