So this is already possible, ok try to use search on forum

.
[added]
I remember that
jcl already answer about Z-Fail shadow, and i understand what perspective shadow impossible
http://www.opserver.de/ubb7/ubbthreads.php?ubb=showflat&Number=255718&Board=6 I in despair, i know what best performance use shadow volume algorithm for point light, shadow mapping is bad for this.