Create player's sight area

[GuillemBarroso]

The player will have two attributes to determine his/her sight area:

• Awareness radius: radius of the circle around the player.
• Vision angle: angle of the cone along the player's aiming direction.
• Vision length: length of the cone along the player's aiming direction

With this, we can determine the player's sight area. Then,

1. Display all the static sprites
2. Apply the fog filter everywhere but in the player's sight area.