Orbit Around

Similar to the Attracted To behavior, the Orbit Around behavior’s default parameter settings give the object sufficient initial velocity to orbit around another object in a perfect circle.

Adjust this behavior using the controls in the Behaviors Inspector:

• Affect Subobjects: A checkbox, available when this behavior is applied to an object that contains multiple objects, such as a group, a particle emitter, a replicator, or a text layer. When this checkbox is selected, all objects enclosed in the parent object are affected individually. When this checkbox is deselected, all objects enclosed in the parent object are affected by the behavior together.

• Object: An object well that defines the object to orbit around. To set the defined target object, drag the object from the Layers list to the Object well in the Orbit Around HUD or Inspector. In the Layers list, you can also drag the target object onto the Orbit Around behavior.

• Strength: A slider that sets the speed of the object.

• Falloff Type: A pop-up menu that determines whether the distance defined by the Influence parameter falls off linearly or exponentially. The default is Linear.

  • Linear: Object attraction falls off in proportion to the object’s distance.

  • Exponential: The closer an object is within the area of influence, the more strongly it is attracted, and the faster it moves toward the object of attraction.

• Falloff Rate: A slider that sets how quickly the force of attraction between objects affected by this behavior falls off. A low Falloff Rate value results in objects quickly getting up to speed as they move toward the object of attraction. A high Falloff Rate causes objects to accelerate much more slowly. When set to Exponential, the attraction falls off more quickly than when set to Linear.

• Influence: A slider that defines the radius of the circle of influence in pixels. Objects that fall within the area of influence move toward the object of attraction. Objects outside the area of influence remain in place.

• Drag: A slider that causes the orbit to decay. The default value for Orbit Around is 0, which results in a stable orbit. Any other value causes the orbit to decay and the object to spiral into the object of attraction.

• Include X, Y, and Z: Buttons that specify the space in which the orbit occurs. For example, when X and Y are enabled, the object orbits in the XY plane. In the illustration below, X and Y are selected in the Include parameter. The red motion paths represent the motion of the white airplanes around the target object (the circle). The light gray box represents the boundary of the group.

  

  In the illustration below, Y and Z are turned on in the Include parameter. The white airplanes move around the target object in the YZ plane.

  

• Pole Axis: A pop-up menu that becomes available when the X, Y, and Z axes are enabled in the Include parameter. Because all points are at a fixed distance from the target or attractor object (the Pole Axis), the object can be visualized on a sphere of all possible orbits, with the target object at the center of the sphere. The Pole Axis defines the two points on the sphere that the orbit must pass through. There are four menu items:

  • X: Aligns the Pole Axis set to the X plane.

  • Y: Aligns the Pole Axis to the Y plane.

  • Z: Aligns the Pole Axis to the Z plane.

  • Random: When Random is selected, the axes shift to a different random position.

• Direction: A pop-up menu that sets whether objects move around in a clockwise or counterclockwise direction.