Learn Unreal Engine 5 AI - Detect and Chase Targets

Table of Contents

1. Introduction
2. Setting up the AI
3. Configuring the AI Perception
4. Logic for detecting and chasing the target
5. Creating the chasing sequence in the behavior tree
6. Adding decorators to control the sequence flow
7. Modifying the player character
8. Customizing the AI behavior
9. Future development and expansion
10. Conclusion

Introduction

In this Tutorial, we will continue with the RPG series and the advanced AI. In the previous episode, we learned how to make the enemy patrol around the level. In this video, we will focus on enabling the enemy to detect and chase a target actor. We will start by setting up the AI controller to give it the ability to perceive objects through sight and hearing. Then, we will implement the logic to detect the target actor and initiate the chase sequence. Finally, we will create a behavior tree sequence for the chasing behavior. Let's get started!

Setting up the AI

To begin, open the BP_AIController blueprint in the AI folder. In this blueprint, we will add the AI Perception component to enable the AI to detect objects. Add the AI Perception component and configure it to detect objects through sight. In the AI Perception configuration, enable the AI Sight sense and leave the default values for now. We will fine-tune these values later to improve gameplay. Additionally, enable detection by affiliation to determine whether the detected actor is an enemy or a friend.

Configuring the AI Perception

In the BP_AIController blueprint, we will implement the logic for detecting and chasing the target actor. We will use the "On Perception Updated" event, which is triggered when the AI detects a new target. In this event, we will obtain the stimulus and get the sense class for the stimulus. Make sure to select the AI Sense Sight class. Next, we will branch based on whether the AI has successfully sensed the target actor. If the target actor is detected, we will set a Blackboard variable named "TargetActor" to store the detected actor. However, if no actor is detected or the sight of the actor is lost, we will clear the "TargetActor" variable. This will ensure that the AI stops chasing the target when it is no longer visible.

Logic for detecting and chasing the target

Now that we have set up the AI Perception and implemented the detection logic in the AI controller, we need to create a behavior tree sequence for the chasing behavior. Open the behavior tree and create a new sequence for the chasing behavior. In this sequence, create a new task named "ChaseTarget" to handle the chasing logic. This task will be based on the BlueprintBase. Implement the logic for chasing the target by using the AI Move To node. Use the "TargetActor" variable from the Blackboard as the destination actor for the AI. This will make the AI move towards the target actor. Additionally, set the "Stop Distance" value to determine the distance at which the AI should stop chasing.

Creating the chasing sequence in the behavior tree

In the behavior tree, add the "ChaseTarget" task to the chasing sequence. This sequence will only be executed if the "TargetActor" variable is set, indicating that a target actor has been detected. To ensure that the chasing sequence has higher priority than other sequences, set its priority to be higher. Additionally, add a decorator to check if the "TargetActor" variable is set. If the variable is not set, the AI will proceed to the patrol sequence.

Adding decorators to control the sequence flow

To control the flow of the behavior tree sequence, we need to add decorators. Decorators are used to make decisions based on conditions. In the chasing sequence, add a Blackboard based decorator and set a condition to check if the "TargetActor" variable is set. This will ensure that the AI only enters the chasing sequence when a target has been detected. In the patrol sequence, add another Blackboard based decorator to check if the "TargetActor" variable is not set. This will ensure that the AI only enters the patrol sequence when no target is detected.

Modifying the player character

In order for the AI to detect the player character, we need to add the Perception Stimuli Source component to the player character blueprint. Configure the component to enable sight perception and set the Auto Register as Source to "False". This will prevent the player character from being detected automatically by the AI. Now, the AI will only detect the player character when the player character is within sight range.

Customizing the AI behavior

The behavior tree and AI setup we have implemented so far are generic and can be customized for different enemy types. For example, for enemy soldiers, we can add additional logic to make them attack the target actor when they reach it. We can also add distractions and other behaviors. Similarly, for boss enemies, we can have a different behavior pattern with more complex logic. The level and area design will also play a role in shaping the AI behavior. As the series progresses, we will explore these possibilities.

Future development and expansion

In future episodes, we will dive deeper into customizing the AI behavior for different enemy types. We will explore more advanced AI features such as attacking, patrolling specific areas, and handling distractions. We will also cover how to create boss AI with unique behavior Patterns. Additionally, we will look into implementing AI for civilian NPCs. The goal is to create a dynamic and engaging gameplay experience with intelligent AI opponents.

Conclusion

In this tutorial, we have learned how to set up AI perception for detecting and chasing a target actor. We have implemented the logic for detecting the target actor and created a behavior tree sequence for the chasing behavior. We have also added decorators to control the flow of the behavior tree. By customizing the AI behavior, we can create more dynamic and engaging gameplay experiences. In the next episode, we will focus on adding attack logic to the AI and further enhancing the enemy behavior. Stay tuned for more exciting tutorials!

Highlights

• Learn how to set up AI perception to detect and chase a target actor
• Implement logic for detecting and chasing the target in the AI controller
• Create a behavior tree sequence for the chasing behavior
• Add decorators to control the flow of the behavior tree sequence
• Customize the AI behavior for different enemy types
• Explore future development and expansion possibilities for the AI system

FAQs

Q: Can I customize the AI behavior for different enemy types? A: Yes, the behavior tree and AI setup can be customized for different enemy types. You can add additional logic for behaviors such as attacking, patrolling specific areas, and handling distractions.

Q: How can I make the AI detect the player character? A: To make the AI detect the player character, you need to add the Perception Stimuli Source component to the player character blueprint and configure it to enable sight perception.

Q: Can the AI be customized to have boss-like behavior? A: Yes, the AI behavior can be customized to have boss-like behavior. You can create a different behavior tree sequence with more complex logic for boss enemies.

Q: Will there be tutorials on implementing AI for civilian NPCs? A: Yes, future episodes will cover the implementation of AI for civilian NPCs and provide guidance on creating dynamic and realistic AI behaviors.

Q: Are there any plans to enhance the AI system further? A: Yes, future episodes will explore more advanced AI features and provide guidance on creating more engaging gameplay with intelligent AI opponents.

Resources

• Unreal Engine Documentation
• Unreal Engine Tutorials