hop-backward

name	hop-backward
description	Hops backward off both feet with a sequence that arcs root.y up and translates root backward while keeping the facing. Use when a command mentions hop back, hop backward, jump back, bounce backwards, or a little jump backward.
category	locomotion
disable-model-invocation	true
subskills	["bend-knees","move-leg"]

hop-backward

A two-footed hop that travels a little BACKWARD while still facing forward. Vertical arc via root.y; translate root backward and OMIT faceDeg so it doesn't spin around.

How

• Backward is the opposite of facing: dz=-cos(face), dx=-sin(face). At face 0 that is -Z, so root.z DECREASES. Use loop:false (ABSOLUTE root) and do NOT set faceDeg.
• Three beats: crouch (root.y:-0.15), airborne (root.y:~0.4, z more negative), land (root.y:0, legs to rest).
• durationMs ~900–1200.

Example

• "hop backward" (at x:0,z:0,faceDeg:0) -> {"durationMs":1100,"say":"Hop back!","sequence":{"loop":false,"frames":[{"t":0,"pose":{"LeftUpLeg":[40,0,0],"LeftLeg":[60,0,0],"RightUpLeg":[40,0,0],"RightLeg":[60,0,0]},"root":{"y":-0.15,"z":0}},{"t":0.5,"pose":{"LeftUpLeg":[55,0,0],"LeftLeg":[65,0,0],"RightUpLeg":[55,0,0],"RightLeg":[65,0,0]},"root":{"y":0.4,"z":-0.6}},{"t":1,"pose":{"LeftUpLeg":[0,0,180],"LeftLeg":[0,0,0],"RightUpLeg":[0,0,180],"RightLeg":[0,0,0]},"root":{"y":0,"z":-1.1}}]}}