In my short experience, negate fcurves method works in lets say 80% of the cases. In the 20% of rest, the animator isn't moving the rig root but the legs or arms controllers individually. In this case the controller's animation isn't mirrable with this method because they aren't symmetrical in relation to their parent object.csaez wrote:That works on simple FK animations, but imagine a character walking in a non orthogonal direction and try to mirror his IK leg with your procedure...
Mirror a pose implies more than copy+negate fcurves, you will probably need a reference object (COG/hips), a symmetry template and some linear algebra to calculate the space switching.
You can wokraround this with temporal nulls, constraints and plot animations to convert the animation to a local space based in the hip or whatever like you said but avoinding doing all that math. You can script it easily and fast. It works for me.
