   Lighting and texturing question
  I have my terrain engine up and running with lighting being calculated. And the terrain looks smooth. My problem is when I apply my textures the terrain doesn''t have the light and dark areas of the polygons? What I am asking is maybe I am confused on what lighting is for in OpenGL. Is lighting just for polygons without textures? When I look at valleys or hillsides I should see more or less light? Lighter or darker textures? Excuse me if I am not making sense but maybe what I am trying to do is going to involve shadows? 