1.4 KiB
Isosurface extraction provenance
CultGeometryIsoSurface is a clean implementation of marching tetrahedra over
a regular scalar grid. The implementation follows the tetrahedral case shape
described by Peter Shirley and Allan Tuchman, “A Polygonal Approximation to
Direct Scalar Volume Rendering,” Computer Graphics 24(5), 1990,
doi:10.1145/99308.99322.
The DELVE/HOLD port was behaviorally motivated by these unversioned local Unity sources:
D:\WIP4\Projects\VoxelTerrain\Assets\Scripts\Procedural\GenerateTerrain.csD:\WIP4\Projects\VoxelTerrain\Assets\Plugins\MarchingCubes.cs
The source directory is not a Git checkout and the plugin carries no license or author notice. Its code and lookup tables were therefore not copied. The CultGeometry implementation uses a fresh six-tetrahedra decomposition, explicit inside/outside classification, interpolation, winding, and flat-normal output.
Deliberate behavior retained:
- scalar samples less than or equal to the isovalue are inside;
- intersections are linearly interpolated along cell edges;
- vertices are emitted per triangle rather than welded;
- output is engine-neutral positions, normals, indices, and material slots.
Deliberate changes:
- no Unity mesh, physics, coroutine, navigation, or random dependency;
- no mutable global target, mode, or winding state;
- outward winding is derived from inside-to-outside direction;
- invalid fields and cell sizes fail at the public boundary.