Implement efficient distance field calculation

[CuddlyBunion341]

A distance field (or distance transform or distance map) is a gridded structure where each cell in the grid represents the shortest distance from that cell to a cell with some other property. Most often that "other property" is a boundary type of cell, such as a wall that a player cannot pass, or the surface of a mesh.
Stack Exchange

This is the basis for a efficient jump list for the glsl raymarcher #21.

Possible implementations

• Grid sweeping
• ...