Hello all, I am a senior in the Game Design and Programming major at Southern New Hampshire University, and I am working on a Proof of Concept for a stealth and detection system.

The asset to create is rather simple: The character must be able to sneak and sprint, and there needs to be an NPC that can search for the player, listen for the player's footsteps (louder if they are sprinting, very quiet if crouching), detect the player and chase the player. So far, I have a character that crouches by default and can sprint, but I'm about to start work on the rest of the asset, and I'm curious if anybody has any recommendations on how to accomplish this in an Unreal 5.3 C++ project. I know that I could simply place down a nav mesh and give the NPC a sight and listener component that comes built into Unreal, but I'd also like to accomplish this task via code if it makes any sense to do so. Thus, I come to you all with your vast experience and knowledge to seek aid. Any resources or tips would be welcome, Thank You!

-Jonathan Savastano

Some simple thoughts:

Visual Detection

1. Check to see if the player is in the enemy's viewing frustum. I use the Radar Method.
2. If in the frustum, cast a ray from the enemy's eye to the player's bounding box(BB) vertices. If all casts return an object other than the player, the player cannot be seen. If all BB verticies are visible, the player is fully visible. If only some are visible, the player is partly hidden. You could make it so the more vertices visible, the more likely the player is to be detected.

Auditory Detection

1. When ever the player make a sound (footsteps, firing weapon), send a message to all enemies that a sound was detected, along with the location
2. Let the enemies decide what to do with the above information when they process messages. If it's far away or there are walls inbetween the location, maybe do nothing. Or maybe just look in that direction. Or investigate (move to that location). A gunshot may produce a stronger response than a floorboard creaking.

Misc

1. When an enemy is engaged with the player, they store the player's location and velocity. If the player becomes not visible (moves behind a wall), the enemy can walk to the player's last known location, then upon arrival investigate by moving in the player's last known direction/velcoity.

2. I found it useful to give enemies a ‘short term memory’ of the player's current location. If the enemy loses sight of the player, the enemy still knows where they are for a small amount of time. This fixes some simple problems like: a. the player strafing out of the enemies viewing frustum. b. Some other object (like a truck) temporarily blocking the enemies view of the player. c. The enemy gets knocked down and ends up on their back looking at the sky.

@scott8

This is some very useful information, thank you so much. That website lighthouse3D seems to have some amazing insight that will be very helpful for me in the future. I'm going to attempt to codify all of this information, wish me luck!

@undefined

Although you are correct and an asset generally refers to artwork, I believe that a code chunk or system could be referred to as an asset as well.

@undefined

Thank you for your input, but I’m here to learn, not to argue semantics with you. It’s a very odd thing to be caught up on, as I think my question was quite clear. My initial post was easily understandable, so your point is moot. Have a nice day, and if you have any real input that has to do with my question, then I’m all ears.

scott8 said:
If in the frustum, cast a ray from the enemy's eye to the player's bounding box(BB) vertices. If all casts return an object other than the player, the player cannot be seen. If all BB verticies are visible, the player is fully visible.

But what if all vertices are occluded, although the player is otherwise partially visible? E.g. if he stands behind a narrow opening in a wall.

I propose to trace at random points in the box volume instead, and make a temporal average over time. This reduces false positives and tells visibility in percentage for the same cost.

@undefined

Good thinking Joe, I’ll take this into consideration as well.