Hey, Jason.

Thanks for reaching out.

So, I’m looking through the chapter now, and I’m not sure what you mean, so please forgive me if I’m not answering your question properly.

On page 301 (Creating the Agent Component), which I’m sure doesn’t align with your reader’s page numbers, there’s a bit of code that you need to add to the didAddToEntity() method. Specifically, the line that reads scene.agentComponentSystem.addComponent(agent) is where that component gets added, causing it to participate in the updates.

Is it possible that you missed that step? If not, maybe I’m misunderstanding what’s happening, which could be the case. Let me know. Thanks!

Also, I’m so happy to read that you’re enjoying the book. I had a lot of fun writing it.

Hi Tammy,

No worries, I struggled a lot with how to explain it, especially since e-readers constantly renumber pages

The actual agent simulation is working, but in the first half of the chapter (Chapter 13—Planning Routes and Creating Believable AI), if the reader is following along doing the coding, the monsters themselves won’t be participating in the update cycle since the MonsterEntity (that get created by the generators) are not yet in the scene’s entity array. The code that gets the monster to choose to chase the player (changes the goal weight for the interceptGoal) comes near the end of the section Use Multiple Goals, where the reader adds an update method to MonsterEntity.

But, the code to update the adding the monster entities into the scene’s entity array isn’t added until later in the chapter, specifically near the end of the section Update Physics for Monsters and Projectiles. So when the reader first tests picking up the key after adding the chase code, the monsters aren’t going to chase them, because the MonsterEntity's update function won’t be triggered yet. I think just relocating the code block that does that to the earlier section would fix it.

if let scene = ocmponentNode.scene as? GameScene {
    scene.entities.append(monsterEntity)
}

Hello again.

Sorry for the late reply. It’s been a heck of a week! Also, I appreciate the additional information you’ve provided.

So, if I understand this issue correctly, it might be more about clarifying why the code gets added where it does versus moving the code to an earlier section. As of now, I’m not sure which is the right way to go. But that’s OK…

I’ll be doing a final read-through this weekend and will make a note to review this chapter’s organization. If it makes sense to move the code, I’ll do that. If not, I’ll add something to the chapter to clarify the reason why it’s done the way it is.

Until then, I’ll keep this topic “unresolved.”

Talk soon!