default boolean connectCorner(IConnectable part, int s, int edgeRot) {
        if (canConnectPart(part, s, edgeRot)) {
            long connMap = getConnMap();
            connMap |= (0x100000000L << edgeRot) << s * 4;
            if (connMap != getConnMap()) {
                setConnMap(connMap);
                onMaskChanged();
            }
            return true;
        }
        return false;
    }
Full block connection mask
<p>
0000 0000 EEEE WWWW SSSS NNNN UUUU DDDD | 00FF FFFF EEEE WWWW SSSS NNNN UUUU DDDD
<p>
For a full block, you can connect through all 6 sides, with 5 connections on each side. (1 through center, and 4 edges)
<p>
First 8 nibbles, straight connections, of nibble of 1 << r where r is a Rotation.rotationTo(blockSide, edgeSide)
D - Down
U - Up
N - North
S - South
W - West
E - East
F - Straight connections to center part or another full block
<p>
Second 8 nibbles, corner face connections:
D - Down
U - Up
N - North
S - South
W - West
E - East
core/src/main/java/mrtjp/projectred/core/tile/IConnectableBlockEntity.java