In modern game development, realistic audio goes beyond simple on/off occlusion. Traditional methods typically use binary checks to determine whether a sound is blocked. In contrast, advanced occlusion systems calculate a dynamic obstruction value, offering nuanced and immersive sound behavior. This post explains how a custom 3D pathfinding solution can be integrated into Unreal Engine to compute realistic occlusion values based on the actual navigation path between a sound emitter and a listener.
Why Use a 3D Pathfinding Approach?
- Enhanced Realism:
Instead of a basic “occluded vs. not occluded” check, our method computes a normalized occlusion value that reflects the complexity of the environment. - Dynamic Adaptation:
By comparing the optimal path (calculated through a 3D grid) with the direct line between source and listener, the system adjusts audio parameters (such as volume, frequency, and spatial effects) in real time. - Flexibility:
The approach allows designers to fine-tune settings based on the geometry of any level, ensuring that sound behaves naturally even in complex environments.
System Overview
1. 3D Grid Generation
- Build Volume:
In Unreal Engine, a designated volume is used to define the area where the navigation grid is generated. This grid represents the traversable space for sound propagation analysis. - Grid Settings:
Configure cell size, resolution, and spatial limits to suit the scale of your level. These parameters ensure that the grid accurately reflects your environment.
2. Asynchronous Pathfinding
- Optimal Path Calculation:
The system performs asynchronous queries to determine the shortest navigable path between the sound emitter and the listener. This process uses the 3D grid data to overcome the limitations of traditional 2D navmeshes. - Performance Focused:
Asynchronous operations help maintain runtime efficiency while calculating complex paths in real time.
3. Occlusion Computation
- Normalized Value:
Once the optimal path is determined, its length is compared with the direct distance. This comparison yields a normalized occlusion value between 0 and 1. - Audio Parameter Adjustment:
The occlusion value is used to dynamically modify audio parameters, such as applying a low-pass filter or adjusting volume, creating a realistic simulation of sound being obstructed by environmental geometry.
Implementation Example
Below is an example code snippet demonstrating how to set up an audio emitter with occlusion enabled.
#include "YourSoundEmitterComponent.h"
// Constructor for an audio emitter actor with occlusion enabled
AMySoundEmitter::AMySoundEmitter()
{
// Create and attach the sound emitter component for occlusion calculations
SoundEmitterComponent = CreateDefaultSubobject<UYourSoundEmitterComponent>(TEXT("SoundEmitterComponent"));
RootComponent = SoundEmitterComponent;
}
// In BeginPlay, initiate a pathfinding query to calculate occlusion
void AMySoundEmitter::BeginPlay()
{
Super::BeginPlay();
// Retrieve the pathfinding subsystem to perform the query
UYourPathfindingSubsystem* PathfindingSubsystem = UYourPathfindingSubsystem::Get(this);
if (PathfindingSubsystem)
{
FVector StartPoint = GetActorLocation();
FVector ListenerPoint = /* Retrieve your listener's location here */;
// Execute asynchronous pathfinding query
PathfindingSubsystem->QueryPathfinding(StartPoint, ListenerPoint,
[this](const FPathfindingResult& Result)
{
if (Result.PathLength > 0.f)
{
// Calculate normalized occlusion based on path distance vs. direct distance
float DirectDistance = FVector::Distance(Result.Origin, Result.Target);
float OcclusionValue = FMath::Clamp(Result.PathLength / DirectDistance, 0.0f, 1.0f);
// Apply the occlusion value to your audio parameters (e.g., attenuation settings)
// Example: AudioComponent->SetFloatParameter("Occlusion", OcclusionValue);
}
}
);
}
}Integrating a custom 3D pathfinding solution with dynamic occlusion calculations can significantly enhance the realism of game audio. By comparing the actual navigable path with a direct line, this system produces a nuanced occlusion value that adjusts sound behavior in real time. This approach not only demonstrates technical prowess but also paves the way for more immersive and interactive audio design in modern game development.
If you’re interested in discussing how this advanced occlusion system can be adapted to your project or learning more about my approach, feel free to reach out at https://mrboombox.com/contact/
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