阴影遮罩的渲染模式。
Set whether static shadow casters should be rendered into real-time shadow maps.
另请参阅：QualitySettings.shadowmaskMode、QualitySettings.shadowDistance。
| Shadowmask | Static shadow casters won't be rendered into real-time shadow maps. All shadows from static casters are handled via Shadowmasks and occlusion from Light Probes. |
| DistanceShadowmask | Static shadow casters will be rendered into real-time shadow maps. Shadowmasks and occlusion from Light Probes will only be used past the real-time shadow distance. |