Function heightFieldGeometry

A regular grid of height samples in the XZ plane, displaced along Y (§53 "height field").

const geometry = heightFieldGeometry({
  heights: samples,        // rows × columns, row-major
  columns: 64,
  rows: 64,
  width: 100,
  depth: 100,
});
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XZ with Y up is the orientation @fourjs/physics' height-field collider (§24) uses, and it is the one terrain, a machined surface, or a scalar field over a plan view arrives in. The field is centred on the origin: x spans [-width/2, width/2] and z spans [-depth/2, depth/2], whatever the heights do.

Normals are central differences of the sampled surface — (−∂y/∂x, 1, −∂y/∂z) normalized, one-sided at the borders — rather than averaged face normals: the height field is a sampled function, so its gradient is the honest normal and costs two subtractions per vertex. Uv is the grid's own parameter square, u with +X and v with +Z.

Unlike every other builder here the grid is open: there is no seam to duplicate, so a rows × columns field is exactly rows · columns vertices.