@luma.gl/engine/src/utils/buffer-layout-order.ts

3D Engine Components for luma.gl

// luma.gl
// SPDX-License-Identifier: MIT
// Copyright (c) vis.gl contributors

import {type BufferLayout, type ShaderLayout} from '@luma.gl/core';

function getMinLocation(
  attributeNames: string[],
  shaderLayoutMap: Record<string, number | undefined>
): number {
  let minLocation = Infinity;

  for (const name of attributeNames) {
    const location = shaderLayoutMap[name];
    if (location !== undefined) {
      minLocation = Math.min(minLocation, location);
    }
  }

  return minLocation;
}

export function sortedBufferLayoutByShaderSourceLocations(
  shaderLayout: ShaderLayout,
  bufferLayout: BufferLayout[]
): BufferLayout[] {
  const shaderLayoutMap = Object.fromEntries(
    shaderLayout.attributes.map(attr => [attr.name, attr.location])
  );

  const sortedLayout = bufferLayout.slice();
  sortedLayout.sort((a, b) => {
    const attributeNamesA = a.attributes ? a.attributes.map(attr => attr.attribute) : [a.name];
    const attributeNamesB = b.attributes ? b.attributes.map(attr => attr.attribute) : [b.name];
    const minLocationA = getMinLocation(attributeNamesA, shaderLayoutMap);
    const minLocationB = getMinLocation(attributeNamesB, shaderLayoutMap);

    return minLocationA - minLocationB;
  });

  return sortedLayout;
}