Wall Repel Behavior

Create panel > Helpers > Object Type rollout > Crowd > Setup rollout > New button > Wall Repel Behavior

Select a Crowd object. > Modify panel > Setup rollout > New button > Wall Repel Behavior

The Wall Repel behavior uses one or more grid objects to repel delegates. When influenced by the Wall Repel force, delegates turn until they're heading away from the grid. It's useful for keeping objects inside an enclosed, straight-sided enclosure, such as a room in a building.

You can set the grids to repel from either side or both sides, and optionally specify a maximum distance for repelling. You can also set the behavior to act as though each grid extends infinitely along its plane.

Note: The Wall Repel behavior simply applies a force on the delegate in the direction opposite the wall; it does not guarantee that the delegate won't go through the wall. If the delegate does go through the wall, adjust settings such as Inner and Outer Distance, and, in particular, try reducing Falloff.


To use the Wall Repel behavior

  1. Add a Wall Repel behavior to the Crowd object.

  2. Add one or more grid objects to the scene, and use the move, rotate, and/or scale functions to set them up.

    Tip: For best results, do not use Mirror to copy a grid to be used with Wall Repel. Use Shift-Clone instead.

  3. In the Wall Repel Behavior rollout, use the None button to designate the grid to repel, or to specify multiple grids, use Multiple Selection.

  4. Change the default settings as desired.

  5. Use Behavior Assignments to assign the behavior to a delegate or team.


Wall Repel Behavior rollout

Grid from which to repel: Set a repelling grid ("source") by clicking the None button and then selecting the grid. Thereafter, the grid's name appears on the button.

To set multiple source grids, click Multiple Selection and use the Select dialog. With multiple source grids, the word "Multiple" appears on the large button.

Method group

Determines whether delegate direction as influenced by the behavior is calculated by an angular method or a force method. Default=Force.

Angle: Applies a force to the delegate based on the angle between the delegate's current direction and the direction it would need to take in order to be moving directly away from the source.

The magnitude of the force is greatest when the delegate is moving directly towards the source, and needs to turn around. It can be as little as 0 when the delegate is moving directly away from the source.

Force: Always applies a force directly away from the source. The magnitude of the force is constant.

Direction group

Determines whether the grid repels from its positive-axis side, its negative-axis side, or both.

To determine which is the positive-axis side, select the grid, and then set the reference coordinate system to Local (the default system is View). Look at the grid in a viewport in which it appears edge-on. The side with the axis sticking out is the positive-axis side, and the opposite side is the negative-axis side.

Tip: For ease of setup, when building a "room" from grids, make sure they all point inward (or outward).

Positive Axis: The grid repels only from the positive-axis side.

Positive Axis: The grid repels only from the negative-axis side.

Both Axes: The grid repels from both sides.

Distance group

Use the distance settings to activate the Wall Repel behavior only when the delegates are within a specific distance from the target. The relative strength of the behavior increases from 0 percent at the outer radius to 100 percent at the inner radius.

Use Distance: When on, the behavior applies only to delegates closer to the target than the Outer Distance value. Default=on.

Inner Distance: The distance from the target at which the force is applied at full strength. Default=0.0.

Outer Distance: The distance from the target at which the force begins to be applied. Default=10.0.

Falloff: The rate at which the repelling force diminishes between the Inner Distance and the Outer Distance. A value of 1.0 indicates a linear falloff. Higher values cause the strength to fall off to zero more rapidly with distance, thus focusing its effect closer to the Inner Distance. Lower values reduce the rate of diminishment, with a Falloff setting of 0.0 indicating that the strength is the same at the Outer Distance as it is at the Inner Distance. Default=2.0.

Display Distance: Shows the inner and outer distance settings as grids offset from the target grid in the viewports. The Inner Distance grid is light blue, while the Outer Distance grid is blue-white. Default=on.

Grid Spacing: Alters the spacing of grid lines used to draw the Inner/Outer Distance grids. The lower the value, the closer the spacing. Default=500.

End force at grid edges: When on, the force emanates only from the grid object. When off, the force emanates from an imaginary infinite grid created by extending the grid plane in all directions.

Color Swatch: Shows the color used to draw the Wall Repel force during the solution. Click the box to choose a different color. Default=violet.

Display Force: The force, when activated, is drawn in the viewports as a wireframe rectangle during the simulation solution. Default=on.