TerrainMaterial

interface TerrainMaterial

import type { TerrainMaterial } from '@driftengine/terrain';

In depth

A weight map baked into vertex colour, and that is the idiomatic answer here rather than a compromise. This engine's colour is vertex data — it is what makes the world one flat-shaded draw call, and the root README says so where it introduces drawMesh's tint. A splat map read by a shader would mean a texture bound on every terrain draw and a branch in flatFrag, which Track D measured at 19.8 KB gzipped for a capability generated into sixteen fragment permutations. This costs nothing at all at runtime: the blend happens once, where the patch is built.

What that gives up, and it is the honest limit: the blend is only as sharp as the mesh. A material boundary inside a cell is drawn as a gradient across that cell, and a patch drawn at a quarter detail blends four times as coarsely as one at full detail. A consumer who wants a sharp line — a road edge, a cliff base — draws that patch at full detail, which is the same dial the geometry already uses.

The weights are read bilinearly, which is the opposite of how a height is read, and the contrast is the whole reason both decisions are written down. A height is read as the triangle because the surface is drawn as triangles and the query has to agree with the picture (heightfield.ts argues that at length). A weight is not drawn: it decides a vertex colour, and the vertex is wherever the mesh put it. There is no triangulation to agree with, so the smooth interpolation is simply the better one — reading a weight map as triangles would put a visible crease along every cell diagonal for nothing.

Properties