[Question] How to follow entity indefinitely/until stopped

[Garfield100]

I'm trying to pick up an item after mining, even if this item drops down to somewhere.
For this I am using the GoalFollow goal, but it doesn't seem to work. The bot stops after reaching the item's initial position and the goal_reached event is fired.
I tried this recursive approach but to no avail:

                           function keepFollowing() {
                                console.log("function keepFollowing called");
                                bot.pathfinder.setGoal(new GoalFollow(itemEntity, 0));
                                bot.once("goal_reached", () => {
                                    console.log("goal_reached fired");
                                    if (!itemGone) {
                                        keepFollowing();
                                    }
                                });
                            }

As you can see in this video, the bot never continues: https://youtu.be/VWl5RxJHCPk

The console output looks like this after the bot has stopped:

function keepFollowing called
goal_reached fired
function keepFollowing called

The bot stops trying to get to the item once it is picked up, by it or by me. This is expected.
Is there a better approach? Did I miss something?

[TheDudeFromCI]

In the setGoal function, you can assign a goal as dynamic to fix this.

const goal = new GoalFollow(entity, 0)
bot.pathfinder.setGoal(goal, true)

[Karang]

This is a problem in mineflayer / prismarine-physics. The item entities movements should be updated by the client and it is not done atm. Can you open an issue in p-physics to request this new feature ? (its a bit more complicated than it sounds because the physic simulation should match exactly the server to not cause desync)

[TheDudeFromCI]

Wait, is that an issue? I tried a similar script on my bot and it seemed to track the item entity fine.

[Karang]

You can view the issue with p-viewer, only the first tick seems to be sent by the server (vanilla). Its the same with throwed potions, but i think arrows are updated. I saw that some time ago in 1.13, if someone can check what s going on also for other versions that would be great

[TheDudeFromCI]

Oh, interesting. I didn't notice that before. Strange.
Wouldn't item drop physics triggered on entityMove events, though?

[Karang]

Yeah it should, but the server only update the position once, so the event is called once.

https://github.com/PrismarineJS/prismarine-viewer/blob/master/lib/mineflayer.js#L82

[Garfield100]

In the setGoal function, you can assign a goal as dynamic to fix this.

const goal = new GoalFollow(entity, 0)
bot.pathfinder.setGoal(goal, true)

Of course I missed something 🤦‍♂️ it works now, thank you very much.
Not sure what you mean @Karang, it fortunately doesn't seem to cause problems in this case.