ATTR_GRAIN

const ATTR_GRAIN: number

import { ATTR_GRAIN } from '@driftengine/drft';

In depth

It takes the next free bit and appends to the end of the payload, so a 1.0 reader meets exactly the arrays it knows in exactly the places it expects them and stops before this one. The asset then draws without grain, which is what a reader that has never heard of grain should produce. Inserting it beside roughness, where it belongs conceptually, would have shifted every array after it and repainted the model with no error raised.