Lighting in Unity

Directional lights represent large, distant sources that come from a position outside the range of the game world. In a realistic scene, they can be used to simulate the sun or moon. In an abstract game world, they can be a useful way to add convincing shading to objects without exactly specifying where the light is coming from. When checking an object in the scene view a directional light is often the quickest way to get an impression of how its shading will appear. For such a test, you are generally not interested in where the light is coming from but simply want to see the object look “solid” and look for glitches in the model.An Area Light is defined by a rectangle in space. Light is emitted in all directions, but only from one side of the rectangle. The light falls off over a specified range. Since the lighting calculation is quite processor-intensive, area lights are not available at runtime and can only be baked into lightmaps.