Basically, I want to modify the rendering system to do the following:
Duplicate the entity's mesh
Identify and isolate the silhouette of the mesh
Extrude the silhouette faces in the direction of the light
Apply an intersection shader (or a fixed-function LWJGL equivalent) to the mesh, so that only parts of the terrain which intersect the shadow mesh are in shadow
I think that by doing this, I'll be able to add shadow volumes to the game. I also plan on modifying the renderer in other ways later on.
I'm unable to find any information on how to do this, however. If anyone could help me hook into the game's renderer and render entities the way I'm trying to here, that would be very much appreciated!