In Blender Cycles, it is possible to automatically (Ctrl+Shift+Numpad 7) put the camera in such a position that the sun's rays shine straight at it. Is it also possible to automatically make the sun rotate so that its rays shine straight at the camera?
Just follow these steps ...
- Select your sun lamp object.
- Hit CTRL + Numpad 0 , set sun lamp as default camera.
- Hit Numpad 0 (Now you are looking from the position of the sun.)
- Hit CTRL + F, use walk mode to position the lamp
- LMB or RMB (depending on your mode of selection) to confirm position.
Cheers, hope that helps.
Perhaps you want a Track To constraint on the lamp targeting the object with To=-Z and Up=Y (although any up != Z would be good.)