如何在一维数组中“变平”或“索引”3d数组?

I am trying to flatten 3D array into 1D array for "chunk" system in my game. It's a 3D-block game and basically I want the chunk system to be almost identical to Minecraft's system (however, this isn't Minecraft clone by any measure). In my previous 2D-games I have accessed the flattened array with following algorithm:I am trying to flatten 3D array into 1D array f