[Panda3D] Horse Mounting State

state_machine_fragment.py

        self.mount_sequence = {npc_name: Sequence()}
        
    def enterHorseMount(self, actor, child, parent):
        if actor and parent and child:
            actor_name = actor.get_name()
            if not self.mount_sequence[actor_name].is_playing():
                # Our horse (un)mounting animations have been made with imperfect positions,
                # so, I had to change child positions to get more satisfactory result
                # with these animations in my game.
                mounting_pos = Vec3(0.5, -0.15, -0.45)
                saddle_pos = Vec3(0, -0.32, 0.16)
                mount_action_seq = actor.actor_interval(anim_names.a_anim_horse_mounting,
                                                        playRate=self.base.actor_play_rate)
                horse_riding_action_seq = actor.actor_interval(anim_names.a_anim_horse_rider_idle,
                                                               playRate=self.base.actor_play_rate)
                actor.set_python_tag("mounted_horse", parent)

                mount_task_name = "{0}_npc_mount_helper_task".format(actor_name.lower())
                taskMgr.add(self.npc_mount_helper_task,
                            mount_task_name,
                            extraArgs=[child, actor, mounting_pos, anim_names.a_anim_horse_mounting],
                            appendTask=True)

                # Horse mounting consists of 13 intervals
                a = Func(child.set_collide_mask, BitMask32.allOff())
                b = Func(self.fsm_state_wrapper, actor, "generic_states", "is_using", True)
                c = Parallel(mount_action_seq,
                             Func(child.reparent_to, parent),
                             Func(child.set_x, mounting_pos[0]),
                             Func(child.set_y, mounting_pos[1]),
                             Func(actor.set_z, mounting_pos[2]),
                             Func(child.set_h, 0),
                             )
                d = Func(child.set_x, saddle_pos[0])
                e = Func(child.set_y, saddle_pos[1])

                # bullet shape has impact of gravity
                # so make player geom stay higher instead
                f = Func(actor.set_z, saddle_pos[2])
                g = Func(child.set_collide_mask, BitMask32.bit(1))
                h = Func(self.fsm_state_wrapper, actor, "generic_states", "is_using", False)
                j = Func(self.fsm_state_wrapper, actor, "human_states", "horse_riding", True)
                k = Func(self.fsm_state_wrapper, actor, "human_states", "is_on_horse", True)
                l = Func(parent.set_python_tag, "is_mounted", True)
                m = Func(taskMgr.remove, mount_task_name)
                n = horse_riding_action_seq

                self.mount_sequence[actor_name].append(a)
                self.mount_sequence[actor_name].append(b)
                self.mount_sequence[actor_name].append(c)
                self.mount_sequence[actor_name].append(d)
                self.mount_sequence[actor_name].append(e)
                self.mount_sequence[actor_name].append(f)
                self.mount_sequence[actor_name].append(g)
                self.mount_sequence[actor_name].append(h)
                self.mount_sequence[actor_name].append(j)
                self.mount_sequence[actor_name].append(k)
                self.mount_sequence[actor_name].append(l)
                self.mount_sequence[actor_name].append(m)
                self.mount_sequence[actor_name].append(n)

                self.mount_sequence[actor_name].start()