The number of split culling planes to use.
Split culling planes are used by XR QuadView rendering to classify visible objects by view region. When set to zero, the split culling path is skipped entirely and there is no overhead for non-QuadView cameras.
Split culling planes are expected to lie within the camera culling volume, acting as a secondary filter on the objects already visible to the camera.
Additional resources: ScriptableCullingParameters.cullingPlaneCount, ScriptableCullingParameters.GetSplitCullingPlane, ScriptableCullingParameters.SetSplitCullingPlane.