カメラが Deferred Light Path の後にステンシルバッファをクリーンにする必要があるかどうか
When using Deferred Shading, the G-buffer and lighting passes use the stencil buffer.
By default contents of the stencil buffer are preserved (not cleared) and end up containing information related
to lights. Setting this property to true makes
stencil be cleared to zero after the deferred light pass is done.
Typically if you're using deferred shading camera and UI elements with Masks (see UI.Mask), you'll want the stencil
buffer to be cleared.