Direction
You have the following options here:
- No Remapping: Nothing changes in the length of the vectors. However, certain Fields can produce undesirable results - e.g., extremely long vectors - which lead to suboptimal results in "normal" processing (you should then use a different option, e.g., Use Value). However, these can be used for your own XPresso calculations. This is also a frequently-used setting for evaluating the flight speed of particles through a Particle Field Layer, for example, in order to adopt the vectors unchanged.
- Normalize: The vector lengths are set to 1 (normal). The desired vector length can then be adjusted directly, e.g., by using the Scale value.
- Use Value: The Value channel defined by the Field is used for the length. A Linear Field, for example, then assigns vector lengths between 0 on the left and 1 on the right.
When using a Particle Field Layer to transfer particle properties, this allows the particle property read out via the value source setting to be multiplied by the normalized vector that you have selected via the Direction Source menu. - Inverse Square: This is a special case that can be used in conjunction with Dynamics. The vector magnitudes then behave similarly to the decrease in brightness of a physical light source in a Spherical Field. Extremely strong at maximum (center of sphere) and then decreasing inversely quadratically with distance. This corresponds, for example, to the physically correct behavior of a gravitational source.
This setting is a multiplier that affects the length of all vectors. For example, if a vector has a length of 4, this will be set to 2 if the Scale value is set to 50%.
Contrary to the remaining settings, this option affects the vector orientation and rotates it 180° in the opposite direction.
Curvature
The following two parameters are only displayed for a Point Object Field level in Curvature mode - i.e., if a geometry is used in the Field list.
Field Force object. Its settings (View tab) can be used to display the directions of action.Primary creates a Field that leads from convex to concave values.
Primary and secondary refer to the two main curvatures of a surface that are perpendicular to each other. Main Curvature is a complex mathematical term, the explanation of which would go too far here (just this much: 2 main curvatures can be assigned to each surface point in space, which you can follow here by selecting the direction of curvature).
By activating this option, you can achieve a smoothing effect, which makes the changes in direction somewhat smoother.