gsk:renderer-render-texture (renderer root &optional viewport)

renderer -- a gsk:renderer instance
root -- a gsk:render-node instance
viewport -- an optional graphene:rect-t instance with the section to draw or the default nil value to use the bounds of root

The gdk:texture instance with the rendered contents of root.

Renders the scene graph, described by a tree of gsk:render-node instances, to a gdk:texture instance. The renderer will acquire a reference on the gsk:render-node tree while the rendering is in progress.

If you want to apply any transformations to root, you should put it into a transform node and pass that node instead.