If this setting is not active, a hard selection will be made, i.e., only those elements that lie within the radius of a given tool will be selected for editing.
Enable this option to display the Soft-Selection in the Viewport.
This setting has nothing to do with the selection tools. It is meant for use in conjunction with most interactive tools for rotation, straightening, moving, curling, etc. - tools that use a soft selection in close proximity around the cursor, independent of any existing selection.
If this setting is active, Tweak will only work with visible guide elements.
Use this setting to define how the falloff should be calculated. You can choose from the following options:
The falloff will only be calculated per guide, over its length.
The falloff will be calculated volumetrically around the selected guide points.
The falloff will be calculated around the roots of the selected guides, and calculated based on these roots, i.e., not matter where the guides lie, the roots (including the entire guide) that lie within the falloff radius will be selected using a single strength value.
Use this setting to define the dimension of the falloff radius:
The positions of the guide points will be used.
The guide points within a specified pixel radius will be selected.
This is the distance from the selection within which the falloff will have an effect. If a value of 0 is entered, a hard selection will be made, i.e., only those guide elements within the radius of the selection tool will be selected. As soon as you increase the Radius setting, the selection will be expanded in accordance with the falloff settings.
This is the strength with which the weighted (soft) selection will be applied. A setting of 0 will result in a hard selection (see previous Radius setting).
Since the falloff is calculated from each guide point outwards, it can occur that some points receive a weighting of more than 100%. If Clip is active, the weighting will be limited to a maximum 100%.
Use this setting to select how the falloff should be calculated from the Radius of the selection tool to the Radius of the soft selection. A depiction of the falloff function can be found here.
Width defines for the Dome, Bell and Needle options how softly or hard the effect should abate within the radius of the tool.
If Spline is selected, the Falloff Curve can be used to create a custom falloff.