Setting an Interpolation Method

Once you create keyframes for a channel, combustion uses interpolation to determine the channel values for the in-between frames. The appearance of the animation depends on the interpolation method used. In Graph mode, the interpolation method is represented by the shape of the curve that joins the keyframes. You can set the interpolation method for an entire curve or for individual keyframes.

Note: In the Animation preferences, you can set Default Keyframe Interpolation. This setting controls the initial Interpolation setting for keyframes.

Types of interpolation are described as follows.

(Mixed)

Indicates that the selected channels contain a variety of interpolation methods. Selecting this option has no effect on the existing keyframes.

Constant

Draws a line of constant value between keyframes. There is no interpolation.

Linear

Draws a straight line from one keyframe to the next, with sharp, abrupt angles when changing values.

Cubic

Draws smooth curves between keyframes, so that the animated channel does not change abruptly at keyframes.

Bezier

Draws smooth curves, similar to cubic interpolation, except that you can adjust the slope of the curve at each keyframe. This can be very useful for adding "ease" to keyframe motion.

Hermite/Flame

Is similar to Bezier with the following difference: you can adjust the direction of the curve, but not how much the curve goes into and out of the keyframe. In other words, you cannot adjust the length of the tangent handle. Use Hermite/Flame for compatibility with the Discreet SGI-based products.

To set the interpolation method:

1. In the Timeline controls, click the Graph button to switch to Graph mode.
2. In the Timeline list, select the channel that you want to animate (if required, expand the categories in the list until the channel is visible).

The animation curve appears in the Timeline view.

3. Select the keyframe(s) you want to change.
4. In the Timeline controls, select an interpolation from the Interpolation list.



The interpolation is applied to all selected keyframes.