is it save light info to one texture for a level?
This is often the case. The environment is often unwrapped on one or more textures. The environmap-geometry needs therefor an additional set of uv-coords and an association to the right lightmap. When rendering, you sample the lightmap like any other texture and use the information to simulate one or more lights. The most simplest way to render a lightmap is just to mulitply the light data with the underlying texture.
so i need save the uv information for every objects, when i render this object, i can use this uv to find the light info in that texture?