Main toolbar > Open Track View > Select a track in the Track View Hierarchy. > Track View toolbar > Assign Controller > Bezier
Graph Editors > Track View > Open Track View > Select a track in the Track View Hierarchy. > Track View toolbar > Assign Controller > Bezier
The Bezier controller is the most versatile controller in gmax. Bezier controllers interpolate between keys using an adjustable spline curve. They are the default controller for most parameters.
Use Bezier controllers whenever you want fully adjustable interpolation between keys. Bezier is the only controller that supports the following:
Dragging tangent handles
Step tangents for abrupt changes from one key to the next
Constant velocity controls
Procedures
To set the tangent type for a key:
Select an object and open the Key Info (Basic) rollout in the Motion panel.
Use the arrows to select a key.
Choose a tangent type from the In or Out tangent flyouts.
To normalize time for a key:
Select an object, and then choose a key to normalize.
You can use the arrows in the Key Info (Basic) rollout to step through keyframes.
On the Motion panel, in the Key Info (Advanced) rollout, click Normalize Time.
The key is moved in time to average the velocity through the key.
Interface
Motion panel > Parameters > Key Info (Basic) rollout
A Key Info dialog with identical parameters to this rollout is available by right-clicking a key in Track View or the Track Bar.
Key number: Shows the current key number. Click the right or left arrows to go to the next or previous key.
Time: Specifies when in time the key occurs.
Time Lock: Controls dragging the key horizontally in Track View edit modes.
X/Y/Z: Adjusts the position of the selected object at the current key.
Key Tangent: Two flyouts set the interpolation properties of the in tangent and out tangent of the key.
Choosing Bezier Tangent Types: Sets the tangent types for one or more keys in the same track using the In and Out tangent flyouts.
Smooth: Creates smooth interpolation through the key.
Linear: Creates linear interpolation at the key.
A linear tangent affects only the curve near the key. Full linear interpolation between two keys occurs only when the Out tangent of the first key and the In tangent of the next key both use a linear tangent.
Step: Creates binary interpolation from one key to the next. Step tangents require a matched set between the Out tangent of one key and the In tangent of the next key.
Choosing Step for the In tangent of the current key also changes the Out tangent of the previous key. Choosing step for the Out tangent of the current key also changes the In tangent of the next key.
Using Step tangents, the outgoing value of a key is held constant until the time of the next key is reached. The value then abruptly jumps to the value of the next key. Use this tangent when you want to animate On/Off switching or instantaneous changes from one value to the next.
Slow: Causes the interpolated rate of change to slow down around the key. A slow In tangent decelerates as it approaches the key. A slow Out tangent begins slow and accelerates as it leaves the key.
Fast: Causes the interpolated rate of change to speed up around the key. The effect is the opposite of using slow. A fast In tangent accelerates as it approaches the key. A fast Out tangent begins fast and decelerates as it leaves the key.
Custom: Displays adjustable tangent handles at the key in Function Curves mode. Choosing Custom for either tangent also sets the other tangent to custom.
Tangent Copy: Copies the tangent type between the tangents of the current key or between the tangents of the previous and next key. Use the arrow buttons on either side of the Key Tangent flyouts.
The left arrow of the In tangent copies to the Out tangent of the previous key.
The right arrow of the In tangent copies to the Out tangent of the current key.
The left arrow of the Out tangent copies to the In tangent of the current key.
The right arrow of the Out tangent copies to the In tangent of the next key.
Choosing Bezier Tangent Types: Sets the tangent types for one or more keys in the same track using the In and Out tangent flyouts.
Bezier Scale Controller (Lock X): Causes the X value to affect all three axes of scale. The Y and Z values are ignored and their function curves are not displayed.
When X is locked, the Y and Z values are not affected by changes in the X value. If you lock X when all three axes are at identical values, alter the X value, and then unlock X, the Y and Z values remain where they were while X retains its new value.
Key Info (Advanced) rollout
Controls velocity in three ways:
Control the absolute velocity at a key using the Velocity Fields
Average velocity over a specified amount of time using Normalize Time
Force constant velocity from one component key to the next using Constant Velocity
In/Out: The In field displays the rate of change as the parameter approaches the key. The Out field displays the rate of change as the parameter leaves the key.
These fields are active only for keys using the Custom tangent type.
The number in the field is the rate of change expressed as parameter units per Tick. By changing the two values for X, Y, and Z you are changing the length and angle of the tangent handle.
Lock button: When on, changing one Custom tangent changes the other by equal but opposite amount. For example, if the Lock button is on and the In value is 0.85, then the Out value is -0.85.
Normalize Time: Averages the position of the keys in time and is applicable to any consecutive blocks of selected keys. Useful if you want to smooth out the motion and have an object that speeds up, slows down, speeds up, and slows down.
Constant Velocity: Interpolates values between a key and the next one in a way that makes the object move at a constant velocity across that curve segment.
Free Handle: Used for automatically updating the length of the tangent handle. When this is turned off, the length of the tangent is at a fixed percentage from its neighboring key. As you move a key, the handles adjust to stay the same percentage away from the neighboring keys. When this is turned on, the handle lengths are based on time lengths.
Create Position Lock Key / Create Rotation Lock Key: Makes the incoming handle of the current key linear, and the out going handle of the previous key linear. This is to prevent overshoot from the spline interpolation.
To use these two features, you must first create a keyboard shortcut in Customize > Customize User Interface. Look for Create Position Lock Key and Create Rotation Lock Key in the keyboard shortcut list and assign a key. You can also press ALT+right-click, and access these commands in the quad menu.