The frames that are between the keys are called interpolation.
These frames automatically calculate the intermediate poses between the keys. The intermediate poses can be calculated in different ways, depending on the type of interpolation.
STEP - a type of interpolation where intermediate frames are not calculated at all. Poses in frames with step interpolation are the same as in the key in front of them.
Open the Chibi_jump_02_keyframes scene to complete the following exercises.
Bezier - a type of interpolation where intermediate poses are calculated so that the trajectories of the character’s points form arcs. In this case, the speed is uneven and strongly depends on neighboring gaps.
Linear - a type of interpolation where the intermediate poses are calculated in such a way that the trajectories between the character’s points follow straight lines with equal speed.
Fixed interpolation is an interpolation where the pose in each frame is set by the user. It is not recalculated automatically.
Fixed interpolation works as if all frames in the interval were keys. Interpolation is automatically fixed if you change the character’s pose outside of the keyframe, in a frame with linear or bezier interpolation.
This way, fixed interpolation allows you to save your changes without creating extra keys.
*If the interpolation interval turns red, then the pose change did not affect all the layers. We will talk more about layers in the next tutorial.
Interpolation is applied to the frame interval between two keys. At different intervals, there may be different types of interpolation. This way, different types of interpolation can be combined to create the desired movement.
With IK interpolation of the arms or legs, the palms and feet will move to a point in the next key along the shortest path — a straight line. This way, the arms will bend in the elbows, and the legs in the knees. With FK interpolation, the entire limb is moved, so the palms and feet make a semicircle.
FK interpolation is useful for sweeping circular motions and movements in the mid-air.