Main toolbar > Open Track View > Function Curves > Show Tangents
Graph Editors menu > Track View > Open Track View > Function Curves > Show Tangents
With Show Tangents you can adjust the tangents of the selected vertices in Function Curves mode. Selected keys must have the Bezier controller with Custom Tangent type assigned.
You can assign the Custom Tangent type only to items using a Bezier controller. To determine if a displayed function curve uses a Bezier controller, turn on the Controller Types filter.
The tangent handles can be either continuous or discontinuous.
Continuous handles behave like a single lever with its pivot point at the key location. Moving either end of the handle also moves the opposite end, maintaining the continuity of the tangent. The function curve, and the animation it represents, moves smoothly through a key with continuous tangent handles.
Discontinuous handles behave like leaves on a hinge, with the hinge pin at the key location. Either end moves independently of the other.
Converting a discontinuous tangent to a continuous tangent requires changing the tangent type from Custom to Smooth and back to Custom again. This technique is performed at the key level and can affect unselected vertices if they belong to the same key as one of the selected vertices.
When using the Custom Tangent type, tangent handles can be moved horizontally in length away from its key frame to affect the shape of the function curve. This affects the amount of influence the key frame has over the interpolation between key frames.
This feature can be used to aid in the slow in and slow out workflow of traditional animation. For example, suppose you are animating a ball bouncing up and down on the worldÆs Z axis. On frame 1, the ball is on the ground; on frame 8, the ball is in the air; on frame 16 the ball is back on the ground. You could adjust the tangents for frame 8 so that their length pulls more of the curve towards its keyframe and away from the key frames on frame 1 and 16. The ball will be more visible on screen near the top of its bounce and blurrier near the points where it touches the ground.
Procedures
To assign a Custom tangent type:
On the Track View toolbar, click Function Curves.
In the Hierarchy list, select a track that uses a Bezier controller (a Position track, for example).
Select one or more keys on the curve.
On the Track View toolbar, click Properties to display the Key Info dialog.
Choose the Custom Tangent type from either In or Out at the bottom of the Key Info dialog.
Tangent handles are displayed on the selected vertices.
To drag continuous tangent handles:
On the Track View toolbar, click Function Curves.
In the Hierarchy list, select a track that uses a Bezier controller (a Position track, for example).
On the Track View toolbar, click one of the Move Keys buttons.
Select one or more keys.
On the Track View toolbar, click Lock Tangents to set one of the following modes:
Inactive: Dragging a tangent handle affects only the single key displaying the handle.
Active: Dragging a tangent handle affects the handles of all selected keys.
Drag either end of the handles to rotate both handles about the key location, or press SHIFT and drag the end of one handle to break continuity and rotate only that handle about the key location.
To edit the horizontal length of a Bezier handle:
First a Custom Tangent type must be assigned to the key frame you want to edit on the function curve.
Make sure Show Tangents is turned on. The toggle is located on the Track View toolbar.
Select the key frame on the function curve. Tangent handles are displayed on the selected key frame.
Select one of the handles and move it horizontally away from its vertex (Key frame).
Interface
Show Tangents: Adjusts the tangents of the selected vertices.
By holding down the SHIFT key, you can edit the tangents of a vertex separately.
Free Handle: Automatically updates the length of the 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.