Trajectories

Select an object. > Motion panel > Trajectories

Scooter following a trajectory

The Trajectories rollout displays the path an object travels over time. Controls to convert splines into trajectories, trajectories into splines, and to collapse any transform controller into editable keys are also available by choosing Motion panel > Trajectories.

Note: The state of the Trajectory check box under Display in the Object Properties dialog (and on the Display panel > Display Properties rollout) controls whether trajectories will be visible for an object.

Using trajectories, you can do the following:

• Display the 3D path for selected objectÆs position tracks.

• Add and delete keys from the path.

• Move, rotate, and scale keys on the path.

• Convert the path to a spline object.

• Derive a new path from a spline object.

• Collapse transforms.

Values under Sample Range are used in the Spline Conversion and Collapse Transform functions.

Procedures

To display an objectÆs trajectory:

1. Select an animated object that moves over time.

2. Right-click the object and choose Properties.

3. Turn on Trajectory, then click OK.

   The Trajectory is displayed as a blue line with white squares and dots. The white squares are keys, the white dots are inbetweens.

To add a key to a trajectory:

1. Select an object.

2. Display the trajectory by following the previous steps.

3. In the Motion panel, click Trajectories.

4. Click Sub-Object to activate Keys and enable editing.

5. Click Add Key.

   The button highlights.

6. Click the trajectory.

   Wherever you click the trajectory a key will be added.

7. Right-click the key and select Key Info from the right-click menu.

   In the Key Info dialog, you can change the In and Out values for the inbetweens on either side of the key. This allows you to use the trajectory key to create the illusion of hesitation or acceleration.

   You can click repeatedly to add many keys in this mode.

To delete a key from a trajectory:

1. Select a key on a trajectory. You can click it, or use window selection.

2. Be sure Add Key is turned off in the Trajectories rollout of the Motion panel.

3. Click Delete Key in the Trajectories rollout of the Motion panel.

   The key is deleted.

To transform keys on a trajectory:

1. Select one or more objects.

2. On the Motion panel, click Trajectories.

3. Click Sub-Object to activate Keys and enable editing.

4. Select one or more keys and use the transform tools on the Main toolbar to move, rotate, or scale the selected keys.

Interface

Sub-Object: Enables key editing. Use the Move, Rotate, and Scale transforms to change the location of a key(s) displayed on a trajectory.

Trajectories rollout

Delete Key: Deletes the selected key(s) from the trajectory.

Add Key: Adds key(s) to the trajectory. This is a modeless tool. When you click this button once, you can add several keys in succession. Click the button again to turn off Add Key mode.

Sample Range group

Start Time/End Time: Specifies the interval for the conversion. If you're converting from position keyframes to a spline object, this is the time interval for which the trajectory will be sampled. If you're converting from a spline object to position keys, this is the interval over which the new keys will be placed.

Samples: Sets the number of samples for the conversion. When converting in either direction, the source is sampled at regular intervals, and keys or control points are created on the target object.

Spline Conversion group

Convert To/Convert From: Converts keyframe position tracks to and from spline objects. This enables you to create a spline trajectory for an object and then convert that spline to keyframes for that object's position track in order to do various keyframe-specific functions (such as applying constant velocity to the keys and normalizing the time). Or, you can convert an object's position keyframes into a spline object.

Tip: Convert to and Convert From can be used to move an object along a path without using a path constraint.

Collapse Transform group

Generates keys based on the current transformation of the selected object. You can apply this for any type of transform controller assigned to an object, but the main purpose of this function is to "collapse" a parametric transform effect, such as one generated by a Path constraint, into standard, editable keys.

Collapse: Collapses the transform of the selected object.

Position, Rotation, Scale: Specifies which transforms you want to collapse.

You must choose at least one check box to activate the Collapse button.