Geometry Culling

Geometry Culling is a feature that helps you remove triangles that are not visible in your game. Simplygon offers several different tools for this purpose, and the most suitable depends on your specific use case and which features it is used in conjunction with.  

Visibility Culling

For visibility culling, you can detect and remove invisible geometry using cameras. This can be combined with the Triangle Reducer, the Remesher and during Object Aggregation. In the default setup with cull occluded geometry setting set to true, Simplygon will place a sphere of cameras around the model and remove any geometry invisible to them. This is especially useful if an asset is only visible from specific angles.

Additionally, other parts of the scene can be marked as occluding, which blocks camera visibility and culls any triangles behind it. You can also use meshes to drive visibility culling. In this case, Simplygon places an omnidirectional camera at each vertex of the mesh, allowing you to use a navigation mesh or camera bounds for visibility culling in a scene.

Volumetric Culling

Volumetric culling can be activated with the Aggregator's EnableGeometryCulling setting flag. This feature efficiently removes triangles encapsulated within a mesh and is ideal for optimizing kit-bashed assets when used during Object Aggregation.

Clipping Geometry and Clipping Planes

While using the Remesher or during Object Aggregation, you can mark other scene geometry as clipping geometry to remove intersecting parts. This is perfect for assets extending below a terrain object, for example. Alternatively, you can use infinitely large clipping planes to uniformly size terrain tiles for HLOD creation.

Automation and Integration

Integrating Geometry Culling with automation in mind can significantly reduce the time-consuming process of manually removing non-visible geometry. It is ideally incorporated into your game’s editor pipeline, ensuring that asset visibility is determined by their placement in relation to others within the game world.

This powerful feature not only reduces the number of triangles needing rendering but also enhances performance by minimizing overdraw, eliminating unnecessary internal shadows, and conserving lightmap space. These optimizations allow you to allocate resources to further increase your game's visual fidelity.

Interested in introducing automated asset optimization to your game production? Contact us for an evaluation.