Foundational voxel engine systems: Generic, Terrain, and Smoothed voxel support

[dyfios]

Is your feature request related to a problem? Please describe.

To develop a robust voxel engine that can support discrete blocky materials and natural, smooth terrain, foundational systems must be established. The engine should be extensible, high performance, and capable of both grid-based and density-based voxel representations.

Describe the solution you'd like

This feature should establish core systems for a voxel engine supporting:

• Generic voxels (blocky, discrete materials)
• Terrain voxels (density fields for natural landscapes)
• Smoothed voxels (continuous surfaces via Marching Cubes or Dual Contouring)

The initial implementation should provide:

• Data structures for different voxel types
• Chunk management for spatial partitioning
• Meshing pipeline hooks to support future LOD, streaming, and editing features

Tasks

• Define Voxel struct with density, material ID, and flags
• Implement Chunk class with chunk coordinates, voxel storage, and mesh references
• Add indexing helpers for 3D voxel arrays
• Create placeholder meshing jobs:
  • Greedy meshing for blocky voxels
  • Marching Cubes prototype for smooth terrain
• Integrate Unity Jobs + Burst for meshing execution
• Generate meshes per chunk and assign to MeshFilter/MeshCollider
• Document architecture decisions (chunk size, density representation, meshing choice)

Requirements & Notes

• Meshing must run off the main thread via Jobs + Burst.
• Code should be structured for extensibility (future LOD, streaming, editing).
• Keep chunk size configurable (default 32³).
• Use Half (fp16) for density to balance precision and memory.
• Mesh generation can be minimal (cubes + basic Marching Cubes), but must demonstrate both blocky and smooth paths.