Texture:getDepthSampleMode
Gets the comparison mode used when sampling from a depth texture in a shader.

Depth texture comparison modes are advanced low-level functionality typically used with shadow mapping in 3D.
compare = Texture:getDepthSampleMode()
compare (nil) CompareMode The comparison mode used when sampling from this texture in a shader, or nil if setDepthSampleMode has not been called on this Texture.