Before we Start

To enable these features, dynamic pathfinding must be enabled to allow the navigation mesh to generate during runtime.

To learn how to enable dynamic generation during runtime click here for our guide.

Only the areas of the level that possessed pawns are near will be generated.

Enabling Generation around Nav Invokers

To enable this setting we must firstly go to the project settings.

Once the project settings are open, click on the Navigation System tab.

Tick the checkbox named: Generate Navigation Only Around Navigation Invoker.

This tells the engine to only generate around actors that have the navigation invoker component.

Nav Invoker Component

To enable navigation generation on an actor, we first need to add the Navigation Invoker Component.

To add this to your actor, click the Add Component button in the top left of your blueprint editor and search for Navigation Invoker.

Once this component is added, setup the radius that the navigation mesh will be generated and removed.

From my testing, the default values work well for open world landscape levels.

When creating a procedurally generated indoor level, I recommend slightly higher values.

This prevents the actor from being trapped in their current room or area.

Demonstration and Example Files

Conclusion

That is all for enabling open world navigation in Unreal Engine 4!

Characters and pawns can now traverse large open or procedurally generated levels.

For further reading into the navigation functions in Unreal Engine, click here for the official documentation.

The post Open World Navigation in Unreal Engine 4 appeared first on Couch Learn.

Switching to Runtime Generation

Firstly, to enable this feature open up your Project Settings.

From here find and click the Navigation Mesh tab under the Engine category.

In the Navigation Mesh settings set the Runtime Generation setting to Dynamic.

Adding Navigation Modifiers

Any actor component that has collision can be setup to cut holes inside the navigation mesh.

To enable this feature, I created a new actor named NavigationBlocker.

This actor stops AI controlled actors from moving in the red area that the collision occupies.

Furthermore, the NavigationBlocker moves around the level, regenerating the navmesh to reflect the changed environment.

To keep it simple, this actor only has a Box Collision.

Click the box collision component from the components list (shown above) and find the navigation category in the details panel on the left.

Tick the Dynamic Obstacle checkbox and set the area class to obstacle.

Area Class

The area class determines how AI controlled actors will react to the modifier.

• None will not affect the navigation.
  
• Default will act like a normal area of navmesh.
  
• LowHeight blocks all AI from navigating through it due to the height restriction.
  
• Null blocks all navigation inside it.
  
• Obstacle tells the AI that this area can be navigated through but only if there are no other possible ways to move to the target.

Example

The AI actor now dynamically adjusts to walk around the box.

To download the project files for this tutorial click below:

Conclusion

With this setup your AI controlled actors will now react to the changing environments.

This system is essential for creating city building or strategy games.

A few examples of games that would use an equivalent system would be Age of Empires, Starcraft and Command and Conquer.

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