In this lesson, you will learn how to configure Hierarchical Level of Detail (HLOD) proxies to consolidate distant geometry into simplified, single-draw-call meshes to maximize rendering performance.
The Core Concept: From Complexity to Proxy
When building vast worlds using World Partition, rendering hundreds of individual static meshes at a great distance places a heavy burden on the CPU and the draw call count. While Nanite helps significantly, for extremely distant terrain or clusters of buildings, even Nanite geometry can be consolidated further. HLODs solve this by taking a group of actors in a distant grid cell and merging them into a single "proxy" mesh with a simplified material and lower triangle density.
Configuring HLOD Generation
To set up HLODs, you first define your strategy within the World Settings under the HLOD System section. You must assign an HLOD Layer, which acts as the blueprint for how the generation process should behave.
Setting Up the Layer
Within an HLOD Layer asset, you configure the HLOD Builder Settings. The most critical parameters here are:
- Proxy Method: Set this to
Simplify Meshto collapse the geometry of multiple actors into one. - Desired Size/LOD Selection: Controls the density of the proxy.
- Material Settings: You can choose to bake out the textures of the grouped actors into a single atlas, drastically reducing the number of materials the GPU needs to switch between.
Once your layers are defined and assigned to the actors in your level, you trigger the generation via the HLOD Outliner (Window > World Partition > HLOD Outliner). Clicking "Generate HLODs" parses your spatial grid cells and creates these proxy assets in your project content folder.
Implementation Workflow
- Navigate to the HLOD Outliner.
- Select your desired HLOD layers.
- Click Generate to allow Unreal to analyze the grid cells and create the consolidated mesh proxies.
When the player moves far enough away, the engine swaps the high-fidelity collection of individual actors for your generated proxy mesh, which the engine renders as one draw call.
Key Takeaway: By consolidating distant object clusters into single HLOD proxy meshes, you drastically reduce draw calls and memory overhead, maintaining high frame rates across expansive, complex environments.