Detect shadows on terrain

Is there any way to access shadows from a realtime directional light? I would like to get the world positions of areas in shadow on a terrain. I got AIs that will avoid direct light and try to move to areas in shadow. So they need to know where to move.

The only thing i could think of is some sort of grid with light values. But I don't really know how to implement it. Any ideas?

 

What is a texture but a grid of values?

(Use a baked lightmap)

 

That is true and exaclty what I need (I think)! I am trying to get the Realtime GI lightmap but I can't find it. This might be totaly wrong but this is as close as I get, and resulting in no lightmap.

Code (CSharp):

1.  
2. Texture2D lightmapColorTexture;
3. Texture2D lightmapDirTexture;
4. LightmapData lightmapData;
5.  
6. lightmapData = LightmapSettings.lightmaps[0];
7. lightmapDirTexture = lightmapData.lightmapDir;
8. lightmapColorTexture = lightmapData.lightmapColor;