Simulation Behaviors

These behaviors perform one of two tasks. Some Simulation behaviors, such as Gravity, animate the parameters of an object in a way that simulates a real-world phenomenon. Other Simulation behaviors, such as Attractor and Repel, affect the parameters of one or more objects surrounding the object to which they’re applied. These behaviors allow you to create some very sophisticated interactions among multiple objects in your project with a minimum of adjustments. Like the Basic Motion behaviors, Simulation behaviors also affect specific object parameters. Examples include Attractor, Gravity, and Repel.

Note: To view examples of working with the different Simulation behaviors, see Behavior Examples.

Important: Several Simulation behavior parameters contain object wells into which target objects used as attractors, repellers, orbiters, and so on, are dragged. Dragging an object to a well may be tricky—be sure to click the object name in the Layers tab and immediately drag the object to the object well (without releasing the mouse button). The behavior must remain active even though you are dragging another object in the Layers tab. If you click the object in the Layers tab and release the mouse button, that object becomes selected, and the behavior’s parameters are no longer displayed. This behavior is true of all wells, including mask source and image wells.

The following sections cover the Simulation behaviors:

Align To Motion

The Align To Motion behavior changes the rotation of an object to match changes made to its direction along an animation path. This behavior is meant to be combined with Simulation behaviors that animate the position of an object or with a keyframed animation path you create yourself.

Note: The Align to Motion behavior does not work on objects animated using the Motion Path behavior. Instead, use the Snap Alignment to Motion behavior (in the Basic Motion subcategory).

Figure. Canvas window showing the effect of the Align to Motion behavior.

Unlike the Snap Alignment to Motion behavior, which produces absolute changes in rotation that precisely match changes in direction, Align To Motion has a springy reaction and creates a more lively effect.

In the above example, the fish travels along the keyframed animation path, but it isn’t aligned to the animation path (notice the rotation handle). Using the Align To Motion behavior, its angle of rotation moves so that it points in the direction of the animation path. By adjusting the Drag parameter, you can make it careen wildly about its anchor point as it goes around curves in the animation path.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Invert Axis: A checkbox that flips the orientation with which the object aligns itself to the motion.
  • Spring Tension: A slider that adjusts how quickly the object’s rotation changes to match a change in the object’s direction. Lower values create a delay between a change to an object’s position and its subsequent change in rotation. Higher values create more responsive changes in rotation.
  • Drag: A slider that adjusts whether or not the change in rotation made by this behavior overshoots the new direction of the object. Low drag values result in springy changes in rotation, where the object rotates back and forth as it overshoots changes in direction. High drag values dampen this effect, making the object’s rotation stick more closely to the changes made in rotation. Higher values also cause the object’s rotation to lag behind the object’s change in position.
HUD Controls

The HUD has controls for the Rotation Axis, Axis, Invert Axis, Spring Tension, and Drag parameters. When applied to a group or layer that contains multiple objects (such as particles, text, or a replicator), the Affect Subobjects checkbox also appears in the HUD.

Related Behaviors

Attracted To

This behavior is part of a group of Simulation behaviors that let you create complex animated relationships between two or more objects. These behaviors are extremely powerful and allow complicated effects to be created with a minimum of steps.

An object with the Attracted To behavior moves toward a single specified target, the object of attraction. Additional parameters allow you to adjust the area of influence that defines how close an object needs to be to move toward the object of attraction, and how strongly it is attracted.

Figure. Canvas window showing animation path created using the Attracted To behavior.

The Drag parameter lets you define whether attracted objects overshoot and bounce about the attracting object, or whether they eventually slow down and stop at the position of the target object.

You can apply two or more Attracted To behaviors to a single object, each with a different object of attraction, to create tug-of-war situations where the object bounces among all the objects it’s attracted to.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Object: An image well that defines the object of attraction. To set the defined target object, drag the object from the Layers tab to the Object well in the Attracted To HUD or Inspector. In the Layers tab, you can also drag the target object onto the Attracted To behavior.
  • Strength: A slider defining the speed at which the object moves toward the object of attraction. With a value of 0, the object doesn’t move at all. The higher the value, the faster the object moves.
  • Falloff Rate: This value determines 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 that are outside of the area of influence remain in place.
  • Drag: A slider that can be used to reduce the distance attracted objects overshoot the object of attraction. Lower Drag values result in the object overshooting the object of attraction, moving past and then careening back around toward the target object again and again. Higher Drag values result in the object coming to rest sooner.
  • Include X, Y, and Z: Buttons that allow you to specify the axes on which the affected object (or objects) moves around the object to which it is attracted. When Z is enabled, the object moves about its attractor object in Z space.
HUD Controls

The HUD has an Object well you can use to assign an object of attraction, as well as Strength, Falloff Type, Falloff Rate, Influence, Drag, and axis assignment parameters. When applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Attractor

If you apply an Attractor behavior to an object, other objects that lie within the area of influence move toward it. You can manipulate the strength with which other objects are attracted, as well as the distance required for attraction to begin.

Figure. Canvas window showing example of Attractor behavior.

By default, objects overshoot the object of attraction and bounce around, never coming to rest. The Drag parameter lets you adjust this behavior, changing whether attracted objects overshoot and bounce around, or whether they eventually slow down and stop at the position of the target object.

The Attractor behavior can affect all objects in the Canvas that fall within the area of attraction, or you can limit its effect to a specific list of objects by using the Affect parameter.

The Attractor behavior can also be applied to objects in motion. If you animate the position of the target object to which you’ve applied the Attractor behavior, all other objects in the Canvas continue to be attracted to its new position.

Parameters in the Inspector
  • Affected Objects: A list that appears when Specific Objects is chosen in the Affect pop-up menu. Drag objects from the Layers tab into this list to be affected by the Attractor behavior when the Specific Objects option is selected in the Affect pop-up menu. To remove an item from the list, select the item and click Remove.
    • Layer: This column lists the name of the layer containing the object.
    • Name: This column lists the name of the object itself.
  • Strength: A slider defining the speed with which attracted objects move toward the target object. With a value of 0, attracted objects don’t move at all. The higher the value, the faster attracted objects move.
  • Falloff Rate: This value determines 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 that are outside of the area of influence remain in place.
  • Drag: A slider that can be used to reduce the distance attracted objects overshoot the object of attraction. Lower Drag values result in the object overshooting the object of attraction, moving past and then careening back around toward the target object again and again. Higher Drag values result in the object coming to rest sooner.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the object (or objects) moves toward the target object. For example, when X and Y are enabled, the object moves in the XY plane; when Y and Z are enabled, the object moves in the YZ plane.
HUD Controls

The HUD lets you adjust the Affect, Strength, Falloff Type, Falloff Rate, Influence, Drag, and axis assignment parameters.

Drag

This behavior lets you simulate the force of friction on a moving object, slowing it down over time. Applying the Drag behavior is an easy way to decelerate objects with multiple behaviors that create complex motion.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Amount: Sliders that can be used to slow down an object over time, causing it to eventually come to a stop. Higher Drag values result in the object coming to rest sooner. Click the Amount disclosure triangle to adjust the drag applied to the X, Y, and Z values separately. An example of this is to create a situation where an object’s vertical speed slows down faster than its horizontal speed.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which drag is in effect. For example, when X and Y are enabled, the object drags in the XY plane; when Y and Z are enabled, the object drags in the YZ plane.
HUD Controls

The HUD lets you adjust the amount of drag and axis assignment. When applied to an object that contains multiple objects, such as a group, particles, text, or the replicator, the Affect Subobjects checkbox also appears in the HUD.

Related Behaviors

Drift Attracted To

Similar to the Attracted To behavior, but by default an object moves toward the object of attraction and comes to rest, rather than overshooting the object of attraction and bouncing around.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Object: An image well that defines the object of attraction. To set the defined target object, drag the object from the Layers tab to the Object well in the Drift Attracted To HUD or Inspector. In the Layers tab, you can also drag the target object onto the Drift Attracted To behavior.
  • Strength: A slider defining the speed at which the object moves toward the object of attraction. With a value of 0, the object doesn’t move at all. The higher the value, the faster the object moves.
  • Falloff Rate: This value determines 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 that are outside of the area of influence remain in place.
  • Drag: A slider that can be used to reduce the distance attracted objects overshoot the object of attraction. Lower Drag values result in the object overshooting the object of attraction, moving past and then careening back around toward the target object again and again. Higher Drag values result in the object coming to rest sooner.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the affected object (or objects) drifts toward the object to which it is attracted. For example, when X and Y are enabled, the object drifts in the XY plane; when Y and Z are enabled, the object drifts in the YZ plane.
HUD Controls

The HUD has an Object well you can use to assign an object of attraction, sliders for strength and drag, and axis assignment. When applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Drift Attractor

Similar to the Attractor behavior, but by default objects within the area of influence move toward the object of attraction and come to rest, rather than overshooting the object of attraction and bouncing around.

Parameters in the Inspector
  • Affected Objects: A list that appears when Specific Objects is chosen in the Affect pop-up menu. Drag objects from the Layers tab into this list to be affected by the Attractor behavior when the Specific Objects option is selected in the Affect pop-up menu. To remove an item from the list, select the item and click Remove.
    • Layer: This column lists the name of the layer containing the object.
    • Name: This column lists the name of the object itself.
  • Strength: A slider defining the speed with which attracted objects move toward the target object. With a value of 0, attracted objects don’t move at all. The higher the value, the faster attracted objects move.
  • Falloff Rate: This value determines 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 Falloff Type is 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 that are outside of the area of influence remain in place.
  • Drag: A slider that can be used to reduce the distance attracted objects overshoot the object of attraction. Lower Drag values result in the object overshooting the object of attraction, moving past and then careening back around toward the target object again and again. Higher Drag values result in the object coming to rest sooner.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the object (or objects) drift toward the target object. For example, when X and Y are enabled, the object drifts in the XY plane; when Y and Z are enabled, the object drifts in the YZ plane.
HUD Controls

The HUD has controls for Affect, Strength, Drag, and axis assignment.

Edge Collision

This is a good behavior to use if you’re setting up complex motion simulations and you don’t want your objects exiting the Canvas. Objects with the Edge Collision behavior applied either come to a stop or bounce off after colliding with the edge of the Canvas frame. For example, if you apply the Throw behavior to an object and set the velocity to send the object toward the edge of the frame, then apply Edge Collision, the object will bounce off the edge of the frame according to the Bounce Strength parameter.

Figure. Canvas window showing animation path created by combining the Throw and Edge Collision behaviors.

The angle at which the object bounces depends on the angle at which it hits the edge of the frame; the speed it travels after bouncing is set by the Bounce Strength parameter.

Note: Edge Collision has no effect on objects that are larger than the Canvas.

Important: By default, the Edge Collision behavior uses the size of the project and the bounding box to determine how the object collides with the edge of the Canvas. For example, in an NTSC Broadcast SD project (720 x 486 pixels), an object bounces off the right and left edges of the project at its bounding box. With groups (particles, text, and objects), only the object’s center is used. You can make the object travel further off the Canvas before it bounces by adjusting the Width and Height parameters. If you’re using this behavior with an object that has an alpha channel that’s smaller than its bounding box, adjust the Crop parameter in the object’s Properties tab to fit the bounding box as closely as possible to the edge of the image.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Bounce Strength: The speed at which objects travel after colliding with an edge. A value of 0 causes objects to come to a complete stop when colliding with an edge that’s perpendicular to the direction of motion. Higher values cause an object to move faster after bouncing. This parameter only slows the object in the direction perpendicular to the bounced edge.
  • Active Edges: Six checkboxes define which collision box edges are detected by the Edge Collision behavior. You can turn edges on and off in any combination.
    • Left Face: Defines the left edge for the collision.
    • Right Face: Defines the right edge for the collision.
    • Top Face: Defines the top edge for the collision.
    • Bottom Face: Defines the bottom edge for the collision.
    • Back Face: Defines the back edge (in Z space) for the collision.
    • Front Face: Defines the front edge (in Z space) for the collision.
  • Width: A slider that allows you to define a width (the right and left edges of the Canvas) other than the size of project. By default, Width is set to the project size.
  • Height: A slider that allows you to define a height (the top and bottom edges) other than the size of project. By default, Height is set to the project size.
  • Depth: A slider that allows you to define a depth (the back and front faces, in Z space) for the edge collision. By default, Depth is set to 100 pixels.
HUD Controls

The HUD has controls for Bounce Strength and Width, Height, and Depth. When applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Gravity

This behavior causes an object, or the objects within a group (when Affect Subobjects is selected), to fall over time. The gravitational acceleration can be increased or decreased, resulting in a change to the rate of fall. Objects affected by the Gravity behavior continue to fall past the bottom edge of the Canvas (unless the Edge Collision behavior has been applied).

Figure. Canvas window showing example of Gravity behavior.

The Gravity behavior can be used in conjunction with other behaviors that animate the position of objects to create natural-looking arcs and animation paths that simulate thrown objects falling to the ground. For example, apply the Throw behavior to an object to send it flying through the air, and then apply the Gravity behavior to it to make the object arc up and then fall down past the bottom of the Canvas.

You can also set the Acceleration parameter to a negative value, effectively applying “anti-gravity” to the object and making it fly up.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Acceleration: A slider defining the strength of gravity affecting the target object. The higher this value, the faster the target object falls.
HUD Controls

The HUD lets you adjust the Acceleration parameter. When applied to an object containing multiple objects (such as a group, particles text, or a replicator), the Affect Subobjects checkbox also appears in the HUD.

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.

Note: Behaviors such as Attractor and Repel applied to nearby objects may disrupt an object with the Orbit Around behavior applied to it.

Figure. Canvas window showing example of Orbit Around behavior.
Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Object: A well that defines the object to orbit around. To set the defined target object, drag the object from the Layers tab to the Object well in the Orbit Around HUD or Inspector. In the Layers tab, you can also drag the target object onto the Orbit Around behavior.
  • Strength: A slider defining the speed at which the object moves.
  • Falloff Rate: This value determines 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 that are outside of the area of influence remain in place.
  • Drag: 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 allow you to 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 yellow motion paths represent the motion of the white stars around the target object (the orange outlined star). The light gray box represents the boundary of the group.
    Figure. Canvas window showing Orbit Around behavior when both X and Y axes are enabled.

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

    Figure. Canvas window showing Orbit Around behavior when both Y and Z axes are enabled.
HUD Controls

The HUD has an image well you can use to assign an object of attraction, as well as controls for Strength, Falloff Type, Falloff Rate, Influence, Drag, axis and Pole Axis assignment, and Direction. When applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Figure. HUD showing controls for Orbit Around behavior including the image well for the object of attraction.

Random Motion

The Random Motion behavior animates the position of an object and makes that object move around the Canvas along a random path.

Figure. Canvas window showing example of the Random Motion behavior.

Although the motion created with this behavior appears to be random, it’s actually predetermined by the particular group of parameters you’ve chosen. As long as you don’t change the parameters, the animation path created by this behavior remains the same. If you don’t like the path that was randomly generated, click the Generate button in either the HUD or the Behaviors tab in the Inspector to pick a new random seed number. This number is used to generate a new path.

The Random Motion behavior is useful for quickly creating varied animation paths for large numbers of objects you want to move at the same time. For example, you can create an arrangement of ten objects in the Canvas and apply the Random Motion behavior to all of them.

You can also use the Random Motion behavior to add variation to the animation paths created by other behaviors that affect an object’s position. For example, adding Random Motion to an object with the Orbit Around behavior results in a more erratic animation path, although it still orbits as before.

Figure. Canvas window showing Orbit Around behavior combined with Random Motion behavior.
Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Amount: A slider that determines the speed the object moves by changing the length of the animation path. Higher values result in faster motion and longer animation paths.
  • Frequency: A slider that determines the number of twists and turns in the animation path, which can be seen by the crookedness of the resulting animation path. Higher values create more turns in the animation path. Lower values result in straighter animation paths.
  • Noisiness: A slider that determines an additional level of jaggedness along the animation path shape defined by the Amount parameter. Higher values result in a more jagged-looking animation path.
  • Drag: A slider that controls the speed the object moves along the animation path. While the Amount parameter controls the length of the animation path, the Drag parameter shrinks or enlarges the animation path as a whole.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which random motion is in effect. For example, when X and Y are enabled, the motion occurs in the XY plane; when Y and Z are enabled, the motion occurs in the YZ plane.
  • Random Seed: A button that lets you pick a new random seed number. This number is used to randomly generate new animation paths, based on the values you’ve picked in the other parameters of this behavior.
HUD Controls

The HUD has controls for the Amount, Frequency, Noisiness, Drag, axis assignment, and Random Seed parameters. When applied to an object that contains multiple objects (such as a group, particles, text, or a replicator), the Affect Subobjects checkbox also appears in the HUD.

Repel

If you apply the Repel behavior to an object, that object pushes away all other objects within the area of influence in the Canvas. The strength with which objects are pushed away can be increased or decreased, as can the distance repelled objects travel.

Figure. Canvas window showing example of Repel behavior.

You can also specify which objects are affected by this behavior, creating an effect where only specific objects are moved, while others remain still.

The Repel behavior is the opposite of the Attractor behavior, and is part of a group of simulation behaviors that create complex animated relationships between two or more objects.

Parameters in the Inspector
  • Affected Objects: A list that appears when Specific Objects is chosen in the Affect pop-up menu. Drag objects from the Layers tab into this list to be affected by the Attractor behavior when the Specific Objects option is selected in the Affect pop-up menu. To remove an item from the list, select the item and click Remove.
    • Layer: This column lists the name of the layer containing the object.
    • Name: This column lists the name of the object itself.
  • Strength: A slider defining the speed with which repelled objects move away from the object. With a value of 0, repelled objects don’t move at all. The higher the value, the faster repelled objects move.
  • Falloff Rate: This value determines how quickly the force of repulsion between objects affected by this behavior falls off. A low Falloff Rate value results in objects quickly getting up to speed as they move away from the object of repulsion. 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 away from the object of repulsion. Objects that are outside of the area of influence remain in place.
  • Drag: A slider that can be used to reduce the distance repelled objects travel away from the repelling object.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the objects move away from the object with the applied Repel behavior. For example, when X and Y are enabled, the object moves away in the XY plane; when Y and Z are enabled, the object moves away in the YZ plane.
HUD Controls

The HUD has controls for which objects are affected, as well as for Strength, Falloff Type, Falloff Rate, Influence, axis assignment, and Drag.

Related Behaviors

Repel From

While the Repel behavior pushes other objects away, the Repel From behavior has the converse effect, making the object it’s applied to move away from a selected object in the Canvas.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Object: An image well that defines the object to be repelled from.
  • Strength: A slider defining the speed at which the object is repelled. With a value of 0, the object is not repelled at all. The higher the value, the faster the object is repelled.
  • Falloff Rate: This value determines how quickly the force of repulsion between objects affected by this behavior falls off. A low Falloff Rate value results in objects quickly getting up to speed as they move away from the object of repulsion. 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 away from the object of repulsion. Objects that are outside of the area of influence remain in place.
  • Drag: A slider that can be used to reduce the distance the object or objects travel away from the repelling object.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the object moves away from the selected object. For example, when X and Y are enabled, the object moves in the XY plane; when Y and Z are enabled, the object moves in the YZ plane.
HUD Controls

The HUD has an image well you can use to assign an object to move away from, as well as controls for Strength, Falloff Type, Falloff Rate, Influence, axis assignment, and Drag. When applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Related Behaviors

Rotational Drag

This behavior is similar to the Drag behavior, except that it affects Rotation instead of position. Rotational Drag simulates friction affecting objects that are spinning due to keyframed or behavior-driven changes to the Rotation parameter. By setting higher Drag values, you can slow rotational changes to an eventual stop.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Amount: A slider that can be used to slow down an object’s rotation over time, causing it to eventually come to a stop. Higher Amount values result in the rotation ending sooner.
HUD Controls

The HUD lets you control the amount of drag. When applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Related Behaviors

Spring

The Spring behavior creates a relationship between two objects, so that an object with the Spring behavior applied to it moves back and forth around a second object. The Attract To parameter defines the object that serves as the target and center of the Spring behavior. Additional parameters let you adjust the speed of the behavior (Spring Tension) and the acceleration of the object at each change in direction (Relaxed Length).

If the Attract To object is at rest, the resulting motion is fairly simple and the springing object moves back and forth in a straight line. If the Attract To object is in motion, the springing object’s motion will be much more complex, changing direction according to the velocity of the Attract To object.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Attract To: An image well that defines the object of attraction. To set the defined target object, drag the object from the Layers tab to the Attract To well in the Spring HUD or Inspector. In the Layers tab, you can also drag the target object onto the Spring behavior.
  • Spring Tension: A slider that determines how fast the object is pulled toward the object of attraction.
  • Relaxed Length: The distance from the target object at which object attraction diminishes to zero. As the springing object’s distance increases past this point, the force of attraction increases proportionally, to bring it back toward the target object.
  • Repel: With this checkbox selected, when the object gets closer to the object of attraction than the Relaxed Length value, the objects are pushed apart. When this checkbox is deselected, no repelling force is applied.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the affected object moves back and forth around the assigned object. For example, when X and Y are enabled, the object moves back and forth in the XY plane; when Y and Z are enabled, the object moves back and forth in the YZ plane.
HUD Controls

An image well in the HUD lets you set the Attract To object. You can also control the Spring Tension and Relaxed Length parameters and axis assignment. A checkbox lets you turn on the Repel parameter. When this behavior is applied to an object that contains multiple objects (such as a group, particles, text, or the replicator), the Affect Subobjects checkbox also appears in the HUD.

Vortex

The opposite of the Orbit Around behavior. While the Orbit Around behavior causes one object to orbit around another target object, the Vortex behavior exerts a force on all objects surrounding the object to which the Vortex behavior is applied.

Parameters in the Inspector
  • Affected Objects: A list that appears when Specific Objects is chosen in the Affect pop-up menu. Drag objects from the Layers tab into this list to be affected by the Attractor behavior when the Specific Objects option is selected in the Affect pop-up menu. To remove an item from the list, select the item and click Remove.
    • Layer: This column lists the name of the layer containing the object.
    • Name: This column lists the name of the object itself.
  • Strength: A slider defining the speed at which the affected objects move about the object of attraction.
  • Falloff Rate: This value determines 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 that are outside of the area of influence remain in place.
  • Drag: The default value for Vortex is 0, which results in a stable vortex. Any other value causes the vortex to decay and the object to spiral into the object of attraction.
  • Include X, Y, and Z: Buttons that allow you to specify the space in which the objects vortex around the target object. For example, when X and Y are enabled, the object circles around in the XY plane; when Y and Z are enabled, the object circles around in the YZ plane.
HUD Controls

The HUD has a pop-up menu that lets you limit the objects affected by this behavior, as well as controls for Strength, Falloff Type, Falloff Rate, Influence, Drag, axis assignment, and Direction.

Wind

Apply the Wind behavior to an object to animate its position and move it in a specified direction. Unlike the Throw behavior, the velocity specified by the Wind behavior is a continuous force, and its parameters can be keyframed to achieve gradual changes in speed and direction.

The Wind behavior is better than the Throw behavior when you want to vary the speed of the object being animated. You can either apply another behavior (such as Randomize or Ramp) or keyframe the Velocity parameter of the Wind behavior to vary the speed and direction of the object. You cannot make gradual changes in either speed or direction with the Throw behavior.

Parameters in the Inspector
  • Affect Subobjects: This parameter appears 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 within the parent object are affected individually. When this checkbox is deselected, all objects within the parent object are affected by the behavior together, as if they were a single object.
  • Air Thickness: A slider and value slider that adjusts how fast the object accelerates on the X, Y, or Z axis when the speed is changed. Lower values (simulating thinner air) have less effect when pushing the object, so it takes longer to get up to speed. Higher values (thicker air) have more effect and push the object up to speed more quickly.
  • Velocity: A slider and value slider that adjust the speed on the X, Y, or Z axis at which the simulated air is blowing the object. Higher values result in faster motion.
HUD Controls

The HUD lets you specify the direction and speed of the Wind behavior by dragging an arrow within a circular region. The direction of the arrow defines the direction of movement in X and Y space, and the length of the arrow defines speed (velocity). A slider to the right lets you adjust the scale of the HUD control, increasing or decreasing the effect the control has over the object.

Figure. HUD showing special controls for the Wind behavior in 2D mode.

Press the Shift key while dragging the arrow to constrain it to 45 degree angles. Press the Command key to change the arrow’s direction without affecting its length.

When you click the 3D button, the HUD allows you to use the center arrow control to define the direction the object is “blown” by the wind in 3D. The Speed slider (on the left side of the HUD) lets you increase or decrease the velocity of the blown object.

Figure. HUD showing special controls for the Wind behavior in 3D mode.

Note: The maximum speed you can define with the HUD is not the maximum speed possible. Higher values can be entered into the Velocity parameter in the Behaviors tab of the Inspector.