Per-layer properties of a ProceduralTextureRequest.
| mipScanlineSize | Datasize (in bytes) of a single scanline of the tile's lower-resolution mip data for this layer, used for trilinear filtering. | 
| requiresCachedMip | Indicates that this request needs both the actual tile data as well as the corresponding data at the next lower-resolution mip. | 
| scanlineSize | Datasize (in bytes) of a single scanline of the tile data for this layer. | 
| GetData | Get a reference to the tile layer data to write texture data to. | 
| GetMipData | Get a reference to the tile layer mip date to write texture data to. |