Pretty much what the title says, I have light that penetrates the terrain. On one side, I have some point lights that emit a purple glow which is specific to that area of the map, I need the area to be bright, so i have the range and intensity kind of high. The problem is directly on the other side of the terrain, the landscape and objects are receiving the purple glow from these lights and I don't want that. Is there a way to stop a light from penetrating an object like the terrain?
In realtime 3D, all polygons in range of a light are lit by angle only, without regard to any other polygons. There's no way to stop this because that's how the hardware works. If you have Unity Pro, you can use realtime shadows, which adds shadows on top of the lighting. Another method is to use layers, so that the purple light affects only objects on a specified layer, and ignores the others. If you don't need the light to be dynamic, you can bake the lighting in a 3D app into a lightmap texture and apply that to all the objects, and not use the light in Unity at all.