function performVoxelsPass(scene, passState, frustumCommands) {
  scene.context.uniformState.updatePass(Pass.VOXELS);

  const commands = frustumCommands.commands[Pass.VOXELS];
  commands.length = frustumCommands.indices[Pass.VOXELS];

  mergeSort(commands, backToFront, scene.camera.positionWC);

  for (let i = 0; i < commands.length; ++i) {
    executeCommand(commands[i], scene, passState);
  }
}
Execute commands to render voxels in the scene.

@param {Scene} scene The scene.
@param {PassState} passState The state for the current render pass.
@param {FrustumCommands} frustumCommands The draw commands for the current frustum.

@private