joints = [arms[], legs[], hands[], head, neck, spines[], waist, hip]
joints[0:6]: left arm
joints[6:12]: right arm
joints[12:18]: left leg
joints[18:24]: right leg
joints[24:29]: left hand (5 fingers)
joints[29:34]: right hand (5 fingers)
joints[34]: head
joints[35]: neck
joints[36]: spine_0
joints[37]: spine_1
joints[38]: waist
joints[39]: hip
