Skip to main content

Top Down Stealth Toolkit Tutorial: How to create a new custom Interest Stimulus

The following information is based on the v2.0 edition of Top Down Stealth Toolkit & hence may not remain entirely relevant in later versions. For more information about the toolkit, check out the official support thread in the Unreal Engine forums:]

The v2.0 update for Top Down Stealth Toolkit introduced a dedicated stimulus driven AI perception system. This tutorial will go over the process of using the aforementioned system to create a new Interest stimulus from scratch.

The base attributes for Interest stimuli are controlled through the 'InterestStimulusDataArray' in BP_AISensoryManager class. Each element of the struct array contains details about a specific type of Interest & hence provide an avenue for easily customizing it's properties. Before going into the actual process of creating a new Interest, I'll provide a brief description of the various parameters that control that control these stimuli.

1. InterestType: Determines the type of Interest associated with the array element.

2. PerceptionType: Determines the AI perception model that can detect this Interest.

3. ThreatClass: Determines the priority level of an Interest when it comes to override requests. For example, an Interest of lower threat class will not override one of higher threat class, thus making sure that the AI retains focus on the stimuli based on their relative importance. By default, all Interests have a threat class level of 1.

4. PerceivedThreatValue: Maintains a normalized [0.0 to 1.0] value of the threat rating of an Interest as perceived by AI agents. Higher values of this parameter will make AI bots go directly into a high alert level state. Within a single cycle of sensory evaluation, Interests with higher value of this parameter within a threat class, are evaluated first to ensure that the AI responds to the most immediate threat.

5. PerceptionRangeModifier: Controls the range at which an Interest can be perceived by adding a distance modifier to the agent's perception checks. For example, Alarm & Gunshot noises have a value of 2.0, thus ensuring that an AI agent possessing a hearing range of 500 m can perceive these stimuli up to double the said distance.

6. PerformRangeTestToInterestCreator: Determines if AI perception tests should conduct distance checks against the actual Interest location, or the entity that created it. For example, perception checks for alarm noises are conducted against the actual source of the noise itself, even though the Interest location would be set as the location of the entity that triggered the alarm.

7. TrackAlertedAgents?: Determines if the Interest object should keep track of agents that have been alerted to it's presence.

8. UseInterestCreatorLocation?: Controls whether the AI agents that detected this stimulus move towards the Interest location or the actor that created it.

9. AutoDeactivate?: Controls the active lifespan of the Interest. For example, noise stimuli have this parameter turned on, thus making them relevant only for a single evaluation cycle.

10. IsInteractive?: Determines if the AI agents can interact with the Interest. If turned off, the AI bots will only investigate the source location.

11. InteractionModel: Controls the manner in which an agent interacts with an interactive Interest. For example, patrol guards will use the 'Reactivate' interaction model to wake up any incapacitated allies they may come across.

12. SortedPriorityOrder: This parameter is set automatically at the start of a game based on the threat class & perceived threat value of the Interest. Ensures that AI Sensory Manager evaluates the Interests with higher priority order before moving on to the rest.

Now in order to create a new Interest, first add a new entry to the enum 'EInterestStimulusType'. All that's left is to add an element to the InterestTypeDataArray for this new type, & assign the parameters mentioned above as per the requirements.

Popular posts from this blog

Unreal Engine 4 Tutorial: Smooth Zoom using Mouse Wheel for Top Down Template

Well, I had already written a tutorial for implementing Smooth Zoom functionality for Top Down Template. But it was based on keyboard inputs. Since most Top Down PC games use mouse wheel for zoom, I decided to make a tutorial for the same. The core logic here is the same as the one implemented by Ryan Jon for the custom camera in his RTS Community Project. If anyone's interested, they can get the code for the RTS Community Project here:

UE4 RTS Community Project

Anyways, he has replaced the default camera for the characters with a general camera since that's more ideal for developing an RTS game. Since a basic Top Down game with a single playable character does not need a separate custom camera, I decided to implement the same functionality for the default player camera in UE4's Top Down Template. So let's get down to it.

First of all we need to make a custom curve from the content browser. We will be using this curve to define the smooth camera movement while zooming …

Unreal Engine 4 Tutorial #4: Basic HUD Based Command UI for Top Down Turn Based Games

Hi, welcome back for the next tutorial. And in this tutorial, I'll be explaining how to create a basic Command UI for top down turn based games using HUD blueprints. By the time we reach the end of the tutorial, we'll have a Command UI with movement and fire action commands, and a player character that responds to the commands. Here's a screenshot showing the end product: 

Oh, and this tutorial is gonna be quite big, compared to earlier ones. So I advise everyone to go through the screenshots, before reading through. If it's clear, there's no need to read through the whole thing, partly because I've written this with a beginner audience target in mind. Ofcourse, if you have doubts, I hope they will be clarified in the written description. If not, feel free to ask me in the comments.
So let's get started. Again, I'll be starting with the top down template. First of all, we need to create a new HUD blueprint. If you're a beginner, you can find this by f…

Unreal Engine 4 Tutorial #3: Unit Selection Decals for RTS Games

Hi, welcome back for another UE4 Tutorial. This time, I'll be walking you through how to set up unit selection decals for RTS games. So the decals need to be visible, when a particular unit is selected, and set to hidden as soon as the unit is deselected. For this tutorial, I'm gonna start off from the Unreal Top Down Template.

First of all, I'll be changing the default controls a bit. Instead of using left mouse button to move the units, I'll be using right mouse button for character movement. I already have a decal texture, that I created in GIMP. If you don't have one, you could get my decal texture from the link below:
DropBox: Character Selection Decal Texture
So once you have the texture ready, next step is to set up your decal material. For creating a decal material, we need to set the 'Material Domain' in the details panel to 'Deferred Decal'. I'm also setting the blend mode to 'Emissive' in my case. Then we multiply the texture wit…