def on_draw(self):
        """
        Run the actual draw calls.
        """
        self._update_meshes()
        gl.glClear(gl.GL_COLOR_BUFFER_BIT | gl.GL_DEPTH_BUFFER_BIT)
        gl.glLoadIdentity()

        # pull the new camera transform from the scene
        transform_camera = self.scene.graph.get(
            frame_to='world',
            frame_from=self.scene.camera.name)[0]

        # apply the camera transform to the matrix stack
        gl.glMultMatrixf(rendering.matrix_to_gl(transform_camera))

        # we want to render fully opaque objects first,
        # followed by objects which have transparency
        node_names = collections.deque(self.scene.graph.nodes_geometry)
        # how many nodes did we start with
        count_original = len(node_names)
        count = -1

        # if we are rendering an axis marker at the world
        if self._axis:
            # we stored it as a vertex list
            self._axis.draw(mode=gl.GL_TRIANGLES)

        while len(node_names) > 0:
            count += 1
            current_node = node_names.popleft()

            # get the transform from world to geometry and mesh name
            transform, geometry_name = self.scene.graph[current_node]

            # if no geometry at this frame continue without rendering
            if geometry_name is None:
                continue

            # if a geometry is marked as fixed apply the inverse view transform
            if self.fixed is not None and geometry_name in self.fixed:
                # remove altered camera transform from fixed geometry
                transform_fix = np.linalg.inv(
                    np.dot(self._initial_camera_transform, transform_camera))
                # apply the transform so the fixed geometry doesn't move
                transform = np.dot(transform, transform_fix)

            # get a reference to the mesh so we can check transparency
            mesh = self.scene.geometry[geometry_name]
            if mesh.is_empty:
                continue

            # add a new matrix to the model stack
            gl.glPushMatrix()
            # transform by the nodes transform
            gl.glMultMatrixf(rendering.matrix_to_gl(transform))

            # draw an axis marker for each mesh frame
            if self.view['axis'] == 'all':
                self._axis.draw(mode=gl.GL_TRIANGLES)

            # transparent things must be drawn last
            if (hasattr(mesh, 'visual') and
                hasattr(mesh.visual, 'transparency')
                    and mesh.visual.transparency):
                # put the current item onto the back of the queue
                if count < count_original:
                    # add the node to be drawn last
                    node_names.append(current_node)
                    # pop the matrix stack for now
                    gl.glPopMatrix()
                    # come back to this mesh later
                    continue

            # if we have texture enable the target texture
            texture = None
            if geometry_name in self.textures:
                texture = self.textures[geometry_name]
                gl.glEnable(texture.target)
                gl.glBindTexture(texture.target, texture.id)

            # get the mode of the current geometry
            mode = self.vertex_list_mode[geometry_name]
            # draw the mesh with its transform applied
            self.vertex_list[geometry_name].draw(mode=mode)
            # pop the matrix stack as we drew what we needed to draw
            gl.glPopMatrix()

            # disable texture after using
            if texture is not None:
                gl.glDisable(texture.target)
Run the actual draw calls.