Implementing Smell Perception in Unity

January 6, 2026

Why Smell Matters in GameAI?

In the real world, animals track prey, avoid predators, and find resources using their sense of smell. Implementing a smell perception system can make your game AI feel more natural, intelligent, and alive.

In this guide, I'll walk you through creating a complete smell perception system from scratch—the same system used in my pirate treasure hunting game.

The Core Concept: How Smell Works in Reality

Smell diffuses from a source outwards

Intensity decreases as distance increases

Different Smell Types (Treasure, Food, Danger, etc.)

Environmental Factors that affect smell travel (wind)

Step 1: Creating the Smell Source

Every Object that emits a smell needs a Smell Source component.

using UnityEngine;

public class SmellSource : MonoBehaviour
{
    // Here you can add your smell types
    public enum SmellType { Treasure }
    
    // Set a default type
    public SmellType smellType = SmellType.Treasure;
    
    // In what radius can the smell be detected
    public float smellRange = 50f;
    
    // This calculates how strong the smell is at any position
    public float getSmellIntensityAt(Vector3 detector_position)
    {
        float distance = Vector3.Distance(transform.position, detector_position);

        // If too far away, no smell
        if (distance > smellRange)
            return 0f;

        // Smell gets weaker with distance
        // Close: 1.0, Far: 0.1
        float intensity = 1f / (1f + distance * 0.1f);

        return intensity;
    }
}

View on GitHub →

Understanding the Math:

I hope it doesn't scare you! Trust me, it's a very simple equation.

Distance Check: First, we check if the detector is within the smell range.

Intensity Formula: 1 / (1 + distance*0.1)

Why this Formula?: It creates a natural decay that matches real-world scent diffusion

As the distance increases, the smell intensity decreases exponentially

That’s all it takes to implement smell decay. Let’s work on the detection part now!

Step 2: Creating the Smell Detector

Now add this function to whatever object you want to give the smell ability.

void checkAllSmells()
{
    // Fetches all smell sources in the scene.
    SmellSource[] all_smells = FindObjectsOfType<SmellSource>();

    // We can multiple smell sources in our game
    foreach (SmellSource smell in all_smells)
    {
        // We calculate the intensity of the smell here
        float intensity = smell.getSmellIntensityAt(transform.position);

        // Add your logic here
    }
}

View on GitHub →

Key Concepts here:

Finding all sources: We check for every smell-emitting object in the scene.

Calculating Local Intensity: Each smell will have a different intensity, depending on the distance between the source and our current position.

And you are all set! That’s all it takes to implement a very simple smell perception in Unity!

Remember: Every great scent system in games makes the virtual world feel more alive. Whether it's a dog tracking treasure or a witcher hunting monsters, smell perception creates connections between characters and their environments that visual systems alone cannot achieve.

Your game world doesn't just need to look real—it needs to smell real too.

using UnityEngine; public class SmellSource : MonoBehaviour { // Here you can add your smell types public enum SmellType { Treasure } // Set a default type public SmellType smellType = SmellType.Treasure; // In what radius can the smell be detected public float smellRange = 50f; // This calculates how strong the smell is at any position public float getSmellIntensityAt(Vector3 detector_position) { float distance = Vector3.Distance(transform.position, detector_position); // If too far away, no smell if (distance > smellRange) return 0f; // Smell gets weaker with distance // Close: 1.0, Far: 0.1 float intensity = 1f / (1f + distance * 0.1f); return intensity; } }

void checkAllSmells() { // Fetches all smell sources in the scene. SmellSource[] all_smells = FindObjectsOfType<SmellSource>(); // We can multiple smell sources in our game foreach (SmellSource smell in all_smells) { // We calculate the intensity of the smell here float intensity = smell.getSmellIntensityAt(transform.position); // Add your logic here } }