function loadLevel(levelID) {
    isLoaded = false;
    world = levels[levelID];
  
    // If we're running in 'SketchUp mode' inside the level editor, tell SU to
    // do the loading, then bail out of here.
    if (isSU) {
      clearTimeout(timerID)
      url = 'skp:do_open@';
      url += 'level_name=' + world.colladaFile;
      url += '&friendly_name=' + world.name;
      window.location.href = url;
      $('export-button').disabled = false;
      $('play-button').disabled = false;
      $('pause-button').disabled = true;
      isLoaded = true;
      return;
    }
  
    var path = window.location.href;
    var index = path.lastIndexOf('/');
    path = path.substring(0, index + 1) + 'levels/' + world.colladaFile;
    $('o3d').style.width = '845px';
    $('o3d').style.height = '549px';
  
    // Create a callback function to prepare the transform graph once its loaded.
    function callback(exception) {
      if (exception) {
        alert('Could not load: ' + path + '\n' + exception);
      } else {
        var current_light = 0;
        var my_effect = pack.createObject('Effect');
        my_effect.name = 'global_effect';
        var effect_string = $('global_effect').value;
        my_effect.loadFromFXString(effect_string);
  
        var xform_nodes = client.root.getTransformsInTree();
        for (var i = 0; i < xform_nodes.length; ++i) {
          var shape_name = xform_nodes[i].name;
          if (shape_name.indexOf('Light') == 0) {
            var world_transform = xform_nodes[i].getUpdatedWorldMatrix();
            var world_loc = world_transform[3];
            var world_location = world_loc;
            var color = [1.0, 0.7, 0.10, 150.0];
  
            var light_index = AddLight(world_location, color);
            xform_nodes[i].parent = null;
            ++current_light;
          }
        }
  
        {
          var materials = pack.getObjectsByClassName('o3d.Material');
          for (var m = 0; m < materials.length; ++m) {
            var material = materials[m];
            if (!material.getParam('diffuseSampler')) {
              diffuseParam = material.createParam('diffuseSampler',
                                                  'ParamSampler');
              diffuseParam.value = blackSampler;
            }
            material.effect = my_effect;
            my_effect.createUniformParameters(material);
            // go through each param on the material
            var params = material.params;
            for (var p = 0; p < params.length; ++p) {
              var dst_param = params[p];
              // see if there is one of the same name on the paramObject we're
              // using for global parameters.
              var src_param = globalParams.getParam(dst_param.name);
              if (src_param) {
                // see if they are compatible
                if (src_param.isAClassName(dst_param.className)) {
                  // bind them
                  dst_param.bind(src_param);
                }
              }
            }
          }
        }
  
        // Remove all line primitives as we don't really want them to render.
        {
          var primitives = pack.getObjectsByClassName('o3d.Primitive');
          for (var p = 0; p < primitives.length; ++p) {
            var primitive = primitives[p];
            if (primitive.primitiveType == o3d.Primitive.LINELIST) {
              primitive.owner = null;
              pack.removeObject(primitive);
            }
          }
        }
  
        o3djs.pack.preparePack(pack, g_viewInfo);
        avatar = world.actors[0];
        isLoaded = true;
        client.setRenderCallback(onRender);
        $('container').style.visibility = 'visible';
      }
    }
  
    // Create a new transform node to attach our world to.
    var world_parent = pack.createObject('Transform');
    world_parent.parent = client.root;
  
    function loadSceneCallback(pack, parent, exception) {
      callback(exception);
    }
    o3djs.scene.loadScene(client, pack, world_parent, path, loadSceneCallback);
  }