title: OpenGL: Using shaders to create vertex lighting by using pre-calculated colormap?
body: <p>First of all, I have very little knowledge of what shaders can do, and i am very interested in making vertex lighting. I am attempting to use a 3d colormap which would be used to calculate the vertex color at that position of the world, and also interpolate the color by using the nearby colors from the colormap.</p>
  
  <p>I cant use typical OpenGL lighting because its probably too slow and theres a lot of lights i need to render. I am going to "render" the lights at the colormap first, and then i could either manually map every vertex drawn with the corresponding color from the colormap.</p>
  
  <p>...Or i could somehow automate this process, so i wouldnt have to change the color values of vertexes myself, but a shader could perhaps do this for me?</p>
  
  <p>Questions is... is this possible, and if it is: what i need to know to make it possible?</p>
  
  <p><strong>Edit:</strong> Note that i also need to update the lightmap efficiently, without caring about the size of the lightmap, so the update should be done only at that specific part of the lightmap i want to update.</p>