You can use the Retime tool to easily speed up or slow down the animation within any time periods on any animation tracks. Also available are options to accelerate and decelerate the time-warped motion.
To use the Retime tool, open Track View in Curve Editor mode and highlight the tracks to retime. Then, after activating the tool, you double-click in the Track View Curve Editor window to place retime markers. Each adjacent pair of vertical markers includes the time between them on the highlighted tracks. You then move the markers to change the animation timing. If you make them closer together, the animation within speeds up; farther apart and the animation slows down.
The Retime tool is somewhat similar to the Region tool in that both scale animation, but they differ in a several ways:
In general, if you're scaling keys in time only, the Retime tool gives you more options and more-predictable results.
The technology underlying the Retime tool is the Ease curve, which applies timing changes to a function curve. Thus you can use the Retime tool with any animated parameter that can take an Ease curve. These include keyframe controllers such as Bezier and Position XYZ, the Noise controller, the Expression controller, the Path constraint's Percent parameter, and so on.
With regard to the two character-animation subsystems in 3ds Max, the Retime tool supports CAT in general, but does not support biped. However, for best results, do not use the Retime tool with the Time Warp feature in CAT. Also, Retime does not directly support procedural animation such as that found in particle systems and physics simulation, but it does if you can bake the animation into keyframes.
To use the Retime tool:
Track View opens in Curve Editor mode. Only animated tracks of the selected object are highlighted in the Hierarchy window of Track View - Curve Editor. This is the default behavior.
All keys belonging to highlighted tracks are affected by the Retime tool, within the horizontal confines that you'll define shortly by placing markers.
A Retime marker appears in the window where you clicked. It takes the form of a vertical yellow bar and bears the legend "Drag to Retime."
Drag the thick central part of the marker to see what happens, then undo the move.
You can use the Retime tool with a single marker, but it only moves the keys; for scaling, you need at least two markers.
A second marker appears, as does a horizontal double-headed arrow between the tops of the two markers.
Retiming markers at frames 20 and 40
Take a moment to observe the markers. Each has a thin line at the top and bottom, a thicker part in the middle, and a small X in a circle at the bottom.
The marker disappears. That's how you delete a marker.
Alternatively, press Ctrl+Z to undo the deletion.
The marker moves but no retiming occurs. Before you start retiming, you can reposition marker freely.
The second marker was moved from frame 40 to frame 34.
Now retiming takes place. If you move the markers farther apart, the time between them expands and the animation they contain slows down. If you move them closer together, the animation speeds up. Meanwhile, time outside and adjacent to the marker you drag moves in the same direction by the same amount. Thus the animation outside the marker pair remains intact, but takes place at a different time.
After retiming, the animation between frames 20 and 34 extends between frames 20 and 50.
As a result, the keys are farther apart than the others and their motion is slower.
This applies no matter how many markers belong to the retimer. You can add multiple markers; moving one affects only adjacent animation on either side. If you drag a marker that is between two other markers, time on the side toward which you drag compresses, while time on the other side expands, but animation beyond the adjacent markers is not affected.
Something else happens the first time you retime with a marker: The whole marker becomes as thick as the central portion. This indicates that you can no longer adjust the marker position without retiming. You can reposition a marker without retiming only before you use it for retiming.
This opens the Retimer Span Type right-click menu, where you can set the span behavior.
To finish this procedure, you'll learn how to move a retimer from one object to another.
This removes the highlighted tracks' animation from the retimer's influence. The retimer remains but is prevented from affecting the object's motion. The object's curves disappear from the Key window to indicate that the animation is no longer subject to editing with this retimer.
After using Remove, the retimer no longer affects the object's animation.
The second object's curves appear, with retiming already applied. This shows that they're now under the influence of the retimer.
The retimer now affects a different object's animation.
Of course, you can also assign additional tracks to a retimer without first removing the existing ones.
The second object's tracks are now using the same retimer that you removed from the first one.
To finalize retiming:
When you're satisfied with the retiming, you can easily bake in the adjustments to make them permanent and remove the overhead imposed by the retimer.
This saves the retimer's changes to the tracks permanently and removes the tracks from the retimer's control. This is indicated by the deletion of the (R#) suffix from each baked track's name. As a result, the tracks are no longer visible.
All animated tracks of selected objects are now visible.
All retimers remain, available for assigning animation tracks.
To use multiple retimers:
You can add as many retimers as you like, each with its own set of markers and its own consequent retiming results. You can use different retimers to control different objects or even different tracks of the same object.
Track View opens in Curve Editor mode. Only animated tracks of the selected object are highlighted in the Hierarchy window of Track View - Curve Editor. This is the default behavior.
As in the preceding procedure, activating the Retime tool creates Retimer 0 and assigns all the highlighted tracks to it.
This adds a second retimer, Retimer 1, to the list. Retimer 1 is highlighted, as indicated by the blue color of its label. The Retimer 0 label turns yellow to show that it is not highlighted.
The label turns blue and the animated tracks' curves and keys again become visible.
Now you can see only keys and curves from the highlighted tracks, whose names change to X Position(R1) and Y Rotation(R1). This indicates that the tracks are under the control of Retimer 1.
Now you can see the remaining tracks that are still under the control of Retimer 0.
In this way you can freely reassign tracks among different retimers. Even if you need a different retimer for each animation track, this is easy to do.
The Retime tool interface is interspersed throughout Track View - Curve Editor. Initial access is through a toolbar button, but the remaining controls are available in the Key window as buttons and draggable, vertical markers.
The Retime tool control panel embedded in the Track View Key window
The Retime tool assigns retimers on a track basis. When you activate the tool, if all highlighted tracks have no retimer assigned, the Retime tool creates a new retimer and assigns the highlighted tracks to it. If any highlighted tracks are already assigned to a retimer, clicking the tool button simply activates the tool.
To exit the Retime tool, click a different button on the Key Controls toolbar or click the Close button (see following).
After baking, the retimer remains and can be assigned any tracks.
Choosing another tool on the Key Controls toolbar also exits the Retime tool.
To activate a retimer and display its markers, click its name in the list. The active retimer's name appears in blue; the rest are yellow.
Available only when the retimer that controls the highlighted track(s) is active, and applies only to the active retimer. For example, if tracks assigned to both R0 and R1 are highlighted and R0 is active, when you click Remove, it acts only upon the tracks assigned to R0. The tracks assigned to R1 are not removed.
In addition to the buttons and list in the top-right corner of Track View, the Retime tool provides control of marker placement, retiming, and other settings directly in the Key window.
Retimer 0 is active with three markers.
Each marker has the following features:
Default (linear, unlocked) time span lines between markers
Time span settings are available on the Retimer Span Type menu, which you open by right-clicking the time span line. Each time span can have different settings.
The menu provides the following controls. The Locked option is a toggle, and of the remaining three options, one can be active at a time.
When a time span is locked, a padlock icon appears superimposed on it.
Left: Locked linear time span; Right: Locked Ease Out time span
A linear time span appears as a double-headed arrow, unless locked (see preceding illustrations).
The Ease In time span resembles an upward slope (from left to right).
The Ease Out time span resembles a downward slope (from left to right).
Left: Ease In; Right: Ease Out