Reference Point
The Reference Point subnode is available only when there is an available incident field defined in the parent node. Then this subnode is available from the context menu (right-click the Port parent node) or from the Physics toolbar, Attributes menu.
The Reference Point subnode defines a reference position rref that is calculated as the average position from the point selection in the Reference Point subnode.
In the parent node, the incident field is then defined using the reference position:
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Point Selection
Select the points that should be used when calculating the reference position. The reference position is calculated as the average position of the selected points.