FOR/OATCUBE/AUTO_TILING

OatCube, you might already know this, but here is a rough sketch on how to optimize your auto tiling.
Assuming you are not already doing something like this.

Key Points :
1. Sprite Sheet For All Auto Tile Sets on ONE BITMAP.
2. 4 Bit Mask to calculate touching value ( t ).

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    //: c : Current Tile   ://
    //:gtv: Get Tile Value ://
    //: t : touching value ://

    var c = gtv( 0 , 0 );

    const ___ = (   0   ) ;
    const x_0 = ( 0 - 1 ) ;
    const x_1 = ( 0 + 1 ) ;
    const y_0 = ( 0 - 1 ) ;
    const y_1 = ( 0 + 1 ) ;


    //:   BINARY:::[   1    1    1    1   ]
    //:   SYMBOLIC:[  x_0  x_1  y_0  y_1  ]


    //:        +-----+
    //:        | y_0 |
    //:        +-----+
    //: +-----++-----++-----+
    //: | x_0 ||  c  || x_1 |
    //: +-----++-----++-----+
    //:        +-----+
    //:        | y_1 |
    //:        +-----+

    //: Sprite Sheet, graphics patterns for all
    //: possible 16 touching values ( t ).

    BINARY: 0000                        BINARY:1111
      |                                      |
    [ 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | ... | 15 ]

    var t =( 0x00
           | ( ( c == gtv( x_0 , ___ ) ) << 3 )
           | ( ( c == gtv( x_1 , ___ ) ) << 2 )
           | ( ( c == gtv( ___ , y_0 ) ) << 1 )
           | ( ( c == gtv( ___ , y_1 ) ) << 0 )
    );;

    /// correct_sub_tile_graphic_index === t ///

    var graphic_origin_x =( t * tile_width_in_pixels );
    var graphic_origin_y =( tile_material_type * tile_height_in_pixels );


    Assuming your sprite sheet looks like

        X cell index === Sub Tile Index
        Y cell index === Material Type Index
        G == Graphic Cell

              0   1   2   3   4   5   6   7   .... SubTileIndex
            +---+---+---+---+---+---+---+---+
         0  | G | G | G | G | G | G | G | G |
            +---+---+---+---+---+---+---+---+
         1  | G | G | G | G | G | G | G | G |
            +---+---+---+---+---+---+---+---+
         2  | G | G | G | G | G | G | G | G |
            +---+---+---+---+---+---+---+---+
         3  | G | G | G | G | G | G | G | G |
            +---+---+---+---+---+---+---+---+
         4  | G | G | G | G | G | G | G | G |
            +---+---+---+---+---+---+---+---+


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