Overview
The Navigation Mesh Resolutions feature gives users the ability to generate Navigation Mesh tiles at 3 different resolutions within the same Navigation Mesh. Users can now generate groups of tiles with a high, medium (default), or low precision setting, which can result in improvements in the generation speed of a dynamic Navigation Mesh at runtime.
In this instance, Navigation Mesh resolution refers to the accuracy and number of cells generated to cover a given navigation space. For example, a high resolution tile might subdivide a given space with more polygons to better approximate the shape of the space. However, a low resolution tile will cover the same space, but use fewer polygons. This results in faster generation of the tiles, at the cost of accuracy.
Common Use Cases
Users can benefit from this feature in the following use cases:
| Use Case | Description |
|---|---|
| Improve Generation Speed | When using Dynamic Navigation Meshes, use low resolution tiles in open spaces or areas where AI Agents don't need good navigation accuracy. Only use default or high resolution tiles in dense areas where AI Agents need to navigate smaller spaces between obstacles. |
| Reduce Memory Footprint | Using low resolution tiles for your Navigation Mesh will result in a smaller memory footprint compared to using default or high resolution tiles. This can benefit games running on hardware with limited memory (like mobile). |
Use Multiple Resolutions with your Navigation Mesh
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Click Add + > Volumes > Nav Mesh Bounds Volume to place a Navigation Mesh Bounds Volume in your level. Press 'P' to visualize the Navigation Mesh.
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Select the RecastNavMesh-Default Actor in the Outliner window. Go to the Details panel and enable the Draw Tile Build Times checkbox. This shows you the time in milliseconds that it took to build each Navigation Mesh tile.
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Click Add + > Volumes > Nav Modifier Volume to place a Navigation Modifier Volume in your level. Place your Modifier Volume so it overlaps with several Navigation Mesh tiles.
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With the Navigation Modifier volume selected, go to the Details panel, then click the Nav Mesh Resolution dropdown and select Low. You can see how the build times are significantly reduced within the Navigation Modifier Volume.
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You can modify Navigation Mesh tile resolutions by using a Nav Modifier component inside an Actor Blueprint. Add the NavModifier component, then go to the Details panel. Select your desired resolution from the Nav Mesh Resolution dropdown.
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In the example below, we created an Actor Blueprint and added the NavModifier component. Then, we selected the Low resolution setting. Notice how the Navigation tiles are rebuilt as the Actor is dragged along the Navigation Mesh volume.
Navigation Mesh Resolution Can Affect Agent Navigation
The Navigation Mesh tile resolution can affect AI Agent navigation pathing. This is especially true when the Agent must navigate between close obstacles or tight spaces.
In the image below, we added 3 obstacles to our Navigation Mesh and set the tile resolution to Low. Notice how there is no available path between the bottom two obstacles. This is because there isn't enough resolution available to create the polygons between those obstacles.
In the example below, we changed the tile resolution to Default. This resolution allows for higher density of polygons, which results in an available path between the bottom two obstacles. In this example the Agent can navigate between those obstacles and its pathing is optimized (straight line).
Optimal Settings
You can change the Navigation Mesh tile resolution settings by following these steps:
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Click Settings > Project Settings to open the Project Settings.
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Click on the Navigation Mesh category and scroll down to the Generation section. Expand the Nav Mesh Resolution Params struct to see the settings for each resolution level.
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You can now change the Cell Size for each resolution level. The bigger the Cell Size, the faster it will generate.
For optimal performance, you can set each Cell Size as a multiple of each other and ensure the Tile Size UU is divisible by all the Cell Sizes.
Debug Tools
You can access the Navigation Mesh tile resolution debug tools by selecting the RecastNavMesh-Default Actor in the Outliner window and going to the Details panel.
Draw Tile Resolutions
Enable the Draw Tile Resolutions checkbox to visualize the resolution of each tile by a different color. The table below shows how each color is related to the tile resolution.
| Resolution | Color |
|---|---|
| Blue | Low resolution. |
| Green | Default resolution. |
| Yellow | High resolution. |
Build Times Heat Map
You can enable the Draw Tile Build Times Heat Map checkbox to visualize a heatmap of tile build times in your Navigation Mesh. Each color represents a build time range, with light blue representing low build time and red representing high build time.
