function DeleteTool(context, root) {
    this.context = context;
    this.root = root;
    this.transformInfo = o3djs.picking.createTransformInfo(root, null);
    this.selectedObject = null;
  }
  
  DeleteTool.prototype.getPickedObject = function(e) {
    var worldRay = o3djs.picking.clientPositionToWorldRay(e.x,
                                                          e.y,
                                                          this.context,
                                                          g_client.width,
                                                          g_client.height);
    this.transformInfo.update();
    var pickInfo = this.transformInfo.pick(worldRay);
    var picked_object_root = null;
    if (pickInfo) {
      pickedObject = pickInfo.shapeInfo.parent;
      while (pickedObject.parent != null &&
             pickedObject.parent.transform != this.root) {
        pickedObject = pickedObject.parent;
      }
      picked_object_root = pickedObject.transform;
    }
    return picked_object_root;
  };
  
  DeleteTool.prototype.handleMouseDown = function(e) {
    this.selectedObject = this.getPickedObject(e);
  };
  
  DeleteTool.prototype.handleMouseUp = function(e) {
    if (this.selectedObject != null &&
        this.selectedObject == this.getPickedObject(e)) {
      // Delete the object if the user clicked down and up on the same object.
      this.selectedObject.setParent(null);
    }
    this.selectedObject = null;
  };
  
  DeleteTool.prototype.handleMouseMove = function(e) {
  };
  
  DeleteTool.prototype.handleKeyDown = function(e) {
    return false;
  };
  
  DeleteTool.prototype.handleKeyUp = function(e) {
    return false;
  };