The demo class I used for the video needs some assets replaced for it to work but should be easy to fix, the usage is:
var dist = 10f;
var pos = cam.getLocation().add(cam.getDirection().mult(dist / 2));
var rot = cam.getRotation();
var projectionBox = new Vector3f(1f, 1f, dist);
var projector = new DecalProjector(map, pos, rot, projectionBox);
var geometry = projector.project();
I will add this to my level editor for adding details to the geometry, but it can be used for many other things like bullet holes, blood splatter, burns, tire tracks, etc. Beware if the geometry is complex it can be slow.
I may add some small features like copying the TextCoord2 buffer and others.
If anybody has any feedback or improvements I’d love to hear.