Voxel engine

A voxel engine is a graphics or simulation system that represents three-dimensional space as a regular grid of volumetric pixels called voxels. Unlike polygonal engines, which represent surfaces as triangle meshes, voxel engines represent space itself: every point in the volume has a value — density, material, color, or occupancy. This makes voxel engines natural for phenomena that are inherently volumetric: fluids, clouds, medical imaging, terrain, and destruction physics.

The central systems challenge of a voxel engine is memory. A 1km³ world at 1cm resolution requires 10¹² voxels — far beyond the capacity of any existing RAM. The solution is to store only non-empty voxels, and the standard technique is spatial hashing: occupied chunks are stored in a hash table indexed by chunk coordinates, while empty space costs nothing. This decouples the logical coordinate system from the physical memory layout, enabling theoretically infinite worlds within finite hardware.

The voxel engine is a test case for a deeper systems principle: representation determines computability. A polygonal engine cannot represent a volumetric explosion without approximating it as surface fragments. A voxel engine cannot represent a smooth sphere without aliasing it into cubes. The choice of engine is a choice of what the world is allowed to be.