You can use custom collada model (flat polygon, as many vertices as you wish inside, let’s say 100x2) and re-arrange vertices in shader so bottom vertex is always in your light position and top is the end of the ray. You just need a way to hide excessive vertices, e.g. by putting top and bottom at light position.
Do you understand the idea? If not, push me in defold.slack (abadonna) and I can try to describe it in Russian 