How to get the vector of the direction player is looking at?

I want to get the direction the player is looking at. I actually want to check which object is in the player's LOS? In order to use Container.raycast(), we need to specify two points between which the raycast is done. I can specify one point as the player's location but need to get the other point in the LOS of the player but some distance away from it. Can anybody help me or suggest any better way of doing it?