Partial rendering of a geometry node

For example a very fancy progress bar with very large number of vertices defining the shape, which would be static except the "how far" to render may change.

Currently scenegraph always renders the whole set of vertices/indices given to it so it has to be dynamically changed which leads to upload every time.

It would be nice if it was possible to have the whole geometry uploaded once and it to remain in GPU memory, but being able to adjust the number of vertices/indices of it to process.