@loaders.gl/3d-tiles/src/lib/parsers/helpers/normalize-3d-tile-normals.ts

3D Tiles, an open standard for streaming massive heterogeneous 3D geospatial datasets.

// loaders.gl
// SPDX-License-Identifier: MIT
// Copyright vis.gl contributors

import {Vector3} from '@math.gl/core';
import {GL, octDecode} from '@loaders.gl/math';
import {Tiles3DTileContent} from '../../../types';

const scratchNormal = new Vector3();

export function normalize3DTileNormalAttribute(
  tile: Tiles3DTileContent,
  normals: Float32Array | null
): {type: number; size: number; value: Float32Array} | null {
  if (!normals) {
    return null;
  }

  if (tile.isOctEncoded16P) {
    const decodedArray = new Float32Array((tile.pointsLength || 0) * 3);
    for (let i = 0; i < (tile.pointsLength || 0); i++) {
      octDecode(normals[i * 2], normals[i * 2 + 1], scratchNormal);
      // @ts-ignore
      scratchNormal.toArray(decodedArray, i * 3);
    }

    return {
      type: GL.FLOAT,
      size: 2,
      value: decodedArray
    };
  }

  return {
    type: GL.FLOAT,
    size: 2,
    value: normals
  };
}