Creating temp nodes inside an enclosed volume

Hi

I have a volume that is enclosed by a mesh of 2D quad and tria elements. I need to fill the inside of this volume with nodes on a regular grid arrangement (in order to generate SPH particles).

My plan was to create a large grid of temp nodes that intersected with the volume and then delete the nodes that lie outside the volume. However I can't figure out a way of doing this.

Can anyone help or suggest a different method?

Thanks