Function togglePrecisionMasking

js/main.js:4215–4233

Toggle precision masking on/off.

(enable)

    vC.set(pos[(i+2) * 3],   pos[(i+2) * 3 + 1],   pos[(i+2) * 3 + 2]);
    e1.subVectors(vB, vA);
    e2.subVectors(vC, vA);
    n.crossVectors(e1, e2).normalize();
    for (let v = 0; v < 3; v++) {
      fn[(i + v) * 3]     = n.x;
      fn[(i + v) * 3 + 1] = n.y;
      fn[(i + v) * 3 + 2] = n.z;
    }
  }
  geometry.setAttribute('faceNormal', new THREE.Float32BufferAttribute(fn, 3));
}

/**
 * Compute area-weighted smooth normals for a non-indexed geometry and store
 * them as a `smoothNormal` vec3 attribute.  Every copy of the same position
 * gets the same averaged normal so vertex-shader displacement is watertight.
 */
function addSmoothNormals(geometry) {
  const pos   = geometry.attributes.position.array;
  const count = geometry.attributes.position.count;
  const nrm   = geometry.attributes.normal.array;

  // Vertex-dedup pass: assign a numeric ID to each unique quantised position.