Animating with the Channel Editor > Animation > Controlling the Speed of Objects >

# Modifying Motion Path Speed

You control the speed of an object on a motion path by modifying the spline. Modify the spline by moving a vertex to a different location. To slow down an object, break a vertex's tangent handles so that you can reshape the spline and redirect the object. To speed up the object, delete a vertex or two from the spline to make it smoother.

Adding Keyframes to a Motion Path

You can add vertices to a motion path. Adding vertices to a motion path also adds a keyframe to the speed curve. The vertex and keyframe are locked, which means that moving the vertex also affects the keyframe. A locked keyframe is represented by a solid square.

(a) Unlocked keyframe(b) Locked keyframe

You can also add keyframes to the speed curve to change the speed of an animation between vertices on the motion path. Adding a keyframe directly to the speed curve does not add a vertex to the motion path; the keyframe is unlocked. You can change the timing of the animation without changing the position of the motion path.

To add keyframes to the speed curve:

1. Click Animation.
2. In the Channel Editor, select the speed curve.
3. From the Edit Mode box, select Add.

   The cursor changes indicating you can add keyframes.

4. In the Animation Curve window, click the speed curve in the location where you want to add the keyframe.

   The added keyframe is unlocked and appears as a square outline.

Removing Keyframes from a Motion Path and Speed Curve

You can delete a vertex from a motion path or delete a keyframe from the speed curve. Deleting a vertex from the spline deletes its associated keyframe from the speed curve, affecting both the shape and speed of the animation. Deleting a locked keyframe from the speed curve unlocks its associated vertex on the spline, allowing you to change the shape of the spline without affecting the animation's speed.

To delete a vertex from the motion path:

1. Click Animation to display the Channel Editor.
2. From the Edit Mode box, choose Select.

   Use Select to edit a particular spline when more than one motion path appears in the image window.

3. From the Edit Mode box, select Delete.

   The cursor changes indicating you can delete keyframes.

4. In the image window, click a vertex on the motion path spline.

   The keyframe is deleted.

To delete a keyframe from the speed curve:

1. Click Animation.
2. In the Channel Editor, select the speed curve.
3. From the Edit Mode box, select Delete.

   The cursor changes indicating you can delete keyframes.

4. On the animation curve, click the keyframe you want to delete.

   The keyframe is deleted.