i can see now whats the problem. If i have for example 6 points (6 for x, 6 for y and 6 for z) i cannot programm a double for loop to define the points of the surface, because this code are trying to save 6*6 points, and i only have 6 points (with 3 coordenates each point).

But, can anybody tell me how to make a surface (with opengl or glunurbs) if a have a collection of coordenates (x,y,z)?