Defines whether Unity frees per-Camera rendering resources for the Terrain when those resources aren't in use after a certain number of frames.
By default, this property is false, which implies that Unity deletes these rendering resources from memory if the Camera they're associated with hasn't rendered for 100 frames. You might sometimes not want this behavior because the next time these resources are required (for example, when that Camera starts to render again), you must reallocate them, which can negatively impact performance. In such cases, set this property to true to keep those resources in memory unless the Camera they're associated with is destroyed. You can also use Terrain.SetKeepUnusedCameraRenderingResources and Terrain.GetKeepUnusedCameraRenderingResources to configure the setting for a specific Camera.
该值不随 Terrain 组件一起序列化。