Attractor Field¶

https://github.com/nortikin/sverchok/assets/14288520/f09028d8-4f03-4dfe-bc3c-d0d57cbb3fa7

Functionality¶

This node generates a Vector Field and a Scalar Field, which are calculated as force attracting points towards some objects. Several types of attractor objects are supported. Several physics-like falloff laws are supported. Falloffs similar to standard proportional editing mode are supported too (they are marked with (P) in the name).

The scalar field generated equals to the norm of the vector field - i.e., the amplitude of the attracting force.

https://github.com/nortikin/sverchok/assets/14288520/3b593948-e9c1-4606-b942-c835baa4419e

Inputs¶

This node has the following inputs:

Center. The exact meaning of this input depends on the Attractor type parameter:
- If attractor type is Point, then this is the attracting point itself;
- if attractor type is Line, then this is the point lying on the attracting line;
- if attractor type is Plane, then this is the point lying on the attracting plane.
- if attractor type is Mesh - Faces or Mesh - Edges, then this is the set of mesh vertices.
- If attractor type is Circle, then this is the center of the circle.
It is possible to provide several attracting points. The default value is (0, 0, 0) (origin).
Direction. The exact meaning of this input depends on the Attractor type parameter:
- if attractor type is Line, then this is the directing vector of the line;
- if attractor type is Plane, then this is the normal vector of the plane.
- with other attractor types, this input is not available.
The default value is (0, 0, 1) (Z axis).
Edges. The edges of the attracting mesh. This input is available only when Attractor type parameter is set to Mesh - Edges.
Faces. The faces of the attracting mesh. This input is available only when Attractor type parameter is set to Mesh - Faces.
Radius. Circle radius. This input is only available when Attractor type parameter is set to Circle.
Amplitude. The attracting force amplitude. The default value is 0.5.
Coefficient. The coefficient used in the attracting force falloff calculation formula. The exact meaning of this input depends on fallof type:
- If Falloff type is set to Inverse exponent or Gauss, then this is the coefficient K in the corresponding formula: exp(-K*R) or exp(-K*x^2/2).
- If Falloff type is set to one of proportional editing modes (one starting with (P) prefix), this is the radius of proportional editing falloff.
- For other falloff types, this input is not available.
The default value is 0.5.

Parameters¶

This node has the following parameters:

Attractor type. The type of attractor object being used. The available values are:
- Point is defined in the corresponding input.
- Line is defined by a point and the directing vector.
- Plane is defined by a point and the normal vector.
- Mesh - Faces is defined by vertices and faces.
- Mesh - Edges is defined by vertices and edges.
The default value is Point.
Join mode. This determines how the distance is calculated when multiple attraction centers are provided. The available values are:
- Average. Calculate the average of the attracting forces towards the provided centers. This mode is used in physics. This option is the default one.
- Nearest. Use only the force of the attraction towards the nearest attraction center.
- Separate. Generate a separate field of attraction force for each attraction center. This parameter is not available when the Attractor type is set to Mesh - Faces.
  - Generator-> NGon
  - List->List Main-> List Decompose
  - Text-> Stethoscope
Signed. This parameter is available only when Attractor type parameter is set to Mesh - faces. If checked, then the resulting scalar field will be signed: it will have positive values at the one side of the mesh (into which the mesh normals are pointing), and negative values at the other side of the mesh. Otherwise, the scalar field will have positive values everywhere. This flag does not affect the calculated vector field. Unchecked by default.
Metric. This parameter is available only when Attractor type parameter is set to Point. The metric to be used to calculate distances. The available options are:
- Euclidean
- Manhattan
- Chebyshev
- Custom. A generic Minkowski metric defined by formula sum(abs(dx_i)**P)**(1.0/P), where P is defined in the Exponent parameter.
The default value is Euclidean.
Exponent. This parameter is available only when Attractor parameter is set to Point, and Metric parameter is set to Custom. Exponent for generic Minkowski distance. The available values are from 1.0 to infinity. The default value is 2.0, which defines Euclidean metric.
Falloff type. The force falloff type to be used. The available values are:
- None - R. Do not use falloff: the force amplitude is proportional to the distance from the attractor object (grows with the distance).
- Inverse - 1/R. Calculate the force value as 1/R.
- Inverse square - 1/R^2. Calculate the force value as 1/R^2. This law is most commonly used in physics.
- Inverse cubic - 1/R^3. Calculate the force value as 1/R^3.
- Inverse exponent - Exp(-R). Calculate the force value as Exp(- K*R).
- Gauss - Exp(-R^2/2). Calculate the force value as Exp(- K * R^2/2).
- (P) Smooth. Equivalent of “Smooth” proportional editing falloff.
- (P) Sphere. Equivalent of “Sphere” proportional editing falloff.
- (P) Root. Equivalent of “Root” proportional editing falloff.
- (P) Inverse Square. Equivalent of “Inverse Square” proportional editing falloff.
- (P) Linear. Equivalent of “Linear” proportional editing falloff.
- (P) Constant. Equivalent of “Constant” proportional editing falloff.
The default option is None.
Clamp. If checked, then the amplitude of attracting force vector will be restricted with the distance to attractor object. Unchecked by default.