- For water, the param is water pressure. 0...127.
- TODO: No, at least the lowest nibble is used for lighting.
-
- - Water will be a bit like light, but with different flow
- behavior.
- - Water blocks will fall down if there is empty space below.
- - If there is water below, the pressure of the block below is
- the pressure of the current block + 1, or higher.
- - If there is any pressure in a horizontally neighboring
- block, a water block will try to move away from it.
- - If there is >=2 of pressure in a block below, water will
- try to move upwards.
- - NOTE: To keep large operations fast, we have to keep a
- cache of the water-air-surfaces, just like with light