Autodesk 62205-051408-9001 User Guide - Page 321

Adjusting the Speed Curve, Restriction for Position Keyframes

Page 321 highlights

Controlling Speed ❚❘❘ percent completion along the path, you do not need to travel the entire distance of the motion path. The motion can start at higher than 0% of the path distance, and can end before 100% of the path distance. Adjusting the Speed Curve You can adjust the Speed curve to create the animation you want. Note: There is no control for speed in the Transform controls for an object. You must set speed in the Timeline, so you can see the entire curve. To adjust the speed of an object: 1. Enable Animate. 2. Select the object. 3. Create a motion path by adjusting position at two different frames (at least). 4. Show the Timeline (F4). 5. Select the Speed channel and make sure it is enabled. Note: In the Animation preferences, you can set Use Speed Channel by Default to control if the Speed channel is enabled or disabled for new layers and objects. 6. Show Graph mode. 7. Do any of the following: • Adjust the tangent handles of the keyframes. • Adjust the Speed value for keyframes. That is, adjust the distance travelled along the motion path at different keyframes (expressed in percentage of total distance). • Add new keyframes (click on curve). Note: When you add a keyframe to the Speed channel, a keyframe is not created in the Position channels. However, if you add one to a Position channel, a corresponding keyframe is added to the Speed channel. • Set the keyframes to use Ease In, Ease Out, or both. 8. Play the clip to see the result of the changes. As the clip plays (or as you step through the clip), you can look at the Position channels (in Graph mode) to see a vertical line that represents the percent completion of distance along the motion path in relation to the object's position. The reference X-axis helps you see this. For more information, see Restriction for Position Keyframes. To reset the Speed curve: 1. Select the Speed channel in the Timeline. 2. Right-click the Speed channel and choose Reset Speed. All keyframes except the first and last are removed. To reset the Speed curve tangent handles: 1. Select the Speed channel in the Timeline. All keyframes are selected automatically. (There is a keyframe for each position keyframe.) 2. Click Reset Tngts. The tangent handles on each Speed keyframe are reset. Restriction for Position Keyframes You can add position keyframes in two ways: • Go to a specific frame and move the object in the viewport. • Add keyframes to the Position channels in the Timeline. In both cases, the motion path changes as a result. When an object has a Speed channel, you cannot move the position keyframes in time. This feature is disabled because it would change the speed along the motion path (and the Speed curve is now controlling speed). 305

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Controlling Speed
305
❚❘❘
percent completion along the path, you do not need
to travel the entire distance of the motion path. The
motion can start at higher than 0% of the path
distance, and can end before 100% of the path
distance.
Adjusting the Speed Curve
You can adjust the Speed curve to create the
animation you want.
Note:
There is no control for speed in the Transform
controls for an object. You must set speed in the
Timeline, so you can see the entire curve.
To adjust the speed of an object:
1.
Enable Animate.
2.
Select the object.
3.
Create a motion path by adjusting position at two
different frames (at least).
4.
Show the Timeline (
F4
).
5.
Select the Speed channel and make sure it is
enabled.
Note:
In the Animation preferences, you can set
Use Speed Channel by Default to control if the
Speed channel is enabled or disabled for new
layers and objects.
6.
Show Graph mode.
7.
Do any of the following:
Adjust the tangent handles of the keyframes.
Adjust the
Speed
value for keyframes. That is,
adjust the distance travelled along the motion
path at different keyframes (expressed in
percentage of total distance).
Add new keyframes (click on curve).
Note:
When you add a keyframe to the Speed
channel, a keyframe is not created in the Position
channels. However, if you add one to a Position
channel, a corresponding keyframe is added to
the Speed channel.
Set the keyframes to use Ease In, Ease Out, or
both.
8.
Play the clip to see the result of the changes.
As the clip plays (or as you step through the clip),
you can look at the Position channels (in Graph
mode) to see a vertical line that represents the
percent completion of distance along the motion
path in relation to the object’s position. The
reference X-axis helps you see this. For more
information, see
Restriction for Position
Keyframes
.
To reset the Speed curve:
1.
Select the Speed channel in the Timeline.
2.
Right-click the Speed channel and choose Reset
Speed.
All keyframes except the first and last are
removed.
To reset the Speed curve tangent handles:
1.
Select the Speed channel in the Timeline.
All keyframes are selected automatically. (There
is a keyframe for each position keyframe.)
2.
Click Reset Tngts.
The tangent handles on each Speed keyframe are
reset.
Restriction for Position Keyframes
You can add position keyframes in two ways:
Go to a specific frame and move the object in the
viewport.
Add keyframes to the Position channels in the
Timeline.
In both cases, the motion path changes as a result.
When an object has a Speed channel, you cannot
move the position keyframes in time. This feature is
disabled because it would change the speed along
the motion path (and the Speed curve is now
controlling speed).