function createMipLevel(size) {
  const texture = new Uint8Array(size);

  // This lookup texture creates an outline with width 0.75 px in screen space.
  texture[size - 1] = 192;

  // As we reach the top of the mip pyramid, a single set pixel becomes a
  // significant portion of the texture. This doesn't look great when zoomed
  // out, so attenuate the value by 50% at each level.
  if (size === 8) {
    texture[size - 1] = 96;
  } else if (size === 4) {
    texture[size - 1] = 48;
  } else if (size === 2) {
    texture[size - 1] = 24;
  } else if (size === 1) {
    texture[size - 1] = 12;
  }
  return texture;
}
Create an outline lookup texture for a single mip level. This is a texture of
mostly 0 values, except for the last value which is brighter to indicate
the outline.

@param {number} size The width of the texture for this mip level
@returns {Uint8Array} A typed array containing the texels of the mip level

@private