CarenStridberg

if you stays in your house for a looog time, you will find that a large number of zombies have spawned at the edge of the block. that's because each block has a spawning limit, when the number of zombies is below the limit, they will keep spawning at the edge of this block, and that's unnatural. This new mechanism is designed to avoid this situation while keep zombies 'alive'.

oh that does't matter. zombie migration happens in area B and C only.

I divided the game area into four areas: A, B, C, and the outside area. The pink triangle represents the character. Zombies outside area A: these zombies will be totally ignored by the game, and their data will not be modified at all. These zombies are actually "dead", so I call this area "THE DEAD AREA". Zombies in area A: 1. Any zombie getting out of this area will be deleted at all. 2. New zombies will spawn at ther edge of this area. In fact, if you want the density of zombies to be a constant (e.g., ρ), and the average speed of zombies is v, and spawning speed of zombies is p (its unit is s^-1 * m^-1, or tick^-1 * m^-1, or something like that. p is the amout of zombies spawned per second on unit length), you will find: p * C = ρ * C * v / 2 that is: p = ρv / 2 (C is assumed to be the grith of this area, and it is eliminated) and that means you can control the amout of zombies by controlling the spawing speed. If you want to furtehr divide this area(area A) into more parts (e.g., towns, forests and so on), you can apply this process to them one by one. And finnally, the density of the zombies will be a constant in area A. that will prevent zombies from stacking in the inactive area of the game. 3. Zombies in this area will move, and all kind of zombies will be treated equally(i.e., no differences between walking zombies and crawlling zombies) to simplify the calculation. Zombies in area B: area B is the active area. Zomvbies there will participate in normal game process. Zombies in area C: the visible area.