1. Go into the game and set all settings to Ultra... or whatever settings you'd like. (This is the MOST important step for this to work correctly. Every time you make graphical changes in the game be sure to carry out step 2 again just to be safe.)
2. Edit variables.txt as follows:
"transparentshadows=1" to "transparentshadows=0"
shadowmapsize=2048 to 1024
The available variables are in alphabetical order... if you do not have this variable... ADD IT.