Inside Terrain Settings, I am trying to increase the Detail Distance over 250, so my grass details will be displayed from a greater distance. How can I do that?
I've tried finding the "Terrain" script to change the code, but couldn't find it.
(where 'terrain' is a reference to the terrain script on the terrain object). A common way to get this reference is to use Terrain.activeTerrain, or to create a public variable of type Terrain, and drag in a reference to the terrain into that variable slot in the editor.
That variable, and a number of others that you might be interested in (such as treeDistance and treeBillboardDistance) are listed on the Terrain Page in the scripting reference.