Twist / Whirld Field#
Functionality#
This node generates a Vector Field, which does Twist or Whirl transformation of some region of space, or combination of Twist and Whirl.
We call Twist a transformation which you get if you take some object, for example a cube, then rotate one of it’s sides (for example, bottom one) around some axis, counterclockwise, and rotate the opposite side (top side, for example) around the same axis clockwise.
Whirl transformation rotates all parts of object in the same direction, just with different angle; the farther from whirl axis, the bigger is rotation angle.
Both Twist and Whirl transformation require some axis for rotation. This axis can be defined by a point, through which the axis goes, and the direction vector.
Inputs#
This node has the following inputs:
Center. Rotation center; a point on twist / whirl axis. The default value is the origin, (0, 0, 0).
Axis. Direction vector of the twist / whirl axis. The default value is Z axis, (0, 0, 1).
TwistAngle. This is not exactly an angle, but a coefficient, which defines the force of twist transformation. More specifically, the plane lying at distance of 1 from rotation center in direction of rotation axis, will be rotated by angle specified in this input; plane passing through rotation center will not be rotated by twist transformation; all other planes perpendicular to rotation axis will be rotated on an angle proportional to distance from rotation center. The value is specified in radians. The default value is pi/2.
WhirlAngle. Similar to previous input, this is not exactly an angle, but a coefficient, which defines the force of whirl transformation. More specifically, points at distance 1 from rotation axis will be rotated by angle specified in this input. All other points will be rotated by angle which is proportional to distance from rotation axis. The value is specified in radians. The default value is 0.
MinZ, MaxZ. These inputs are available only when Use Min Z / Use Max Z parameters are enabled. Both twist and whirl transformation will stop at these distances from rotation center along rotation axis. Positive direction of rotation axis is the one defined by Axis input. The default values are 0.0 and 1.0, correspondingly.
MinR, MaxR. These inputs are available only when Use Min R / Use Max R parameters are enabled. Both twist and whirl transformations will be ceased for points which have distance from rotation axis below MinR or above MaxR values. The default values are 0.0 and 1.0.
Parameters#
This node has the following parameters:
Use Min Z, Use Max Z. If enabled, these parameters will allow to define a part of space along rotation axis which will be transformed; space outside this area will not be twisted any further.
Use Min R, Use Max R. If enabled, these parameters allow to define a (cylindrical) part of space in terms of distance from rotation axis, which should be transformed; outside this area, the space will not be twisted any further.
Outputs#
This node has the following output:
Field. The generated vector field.
Examples of usage#
Example of Twist transformation:
Example of Whirl transformation:
Twist and Whirl combined: