1. Select the Animation animation, bones.
2. After selecting the bone, click Key
After clicking Key, Additive Layer Tracks will add a layer track.
3. Select the edit curve (Translation translation, Rotation rotation, Scale zoom), and the selected Rotation in the figure rotates.
4. Select the axis to be edited (X, Y, Z). After selecting the axis, click the triangle , and two input boxes will appear, indicating the value.
5. Setting parameters
6. Click Apply
After clicking to play the animation, you can see that the K frame just now has been applied.
If you don't need this K frame, you can Remove Track to remove it
after removing
PS: In the Animation animation editor, bones can be selected for adjustment, but only for demonstration. It cannot be saved to the animation to achieve the effect of K frames.
Add it to the scene and find that the left arm movement that was just adjusted has not changed. The right arm is the effect after the K-frame application just now.
Demonstrated in the picture, Unreal Engine version 4.25.