hi! i'm still new to the opengl. just wondering how could i possibly simulate a wrinkle, where the wrinkle shape function is given. all i have to do is draw a portion of human forehead and apply the function to it. any ideas or tricks in doing so? tq

For high poly objects, you could use blendshapes or displacement maps.
For low and medium poly objects, two normal maps(+ blendshape) could be used.
For really low poly objects, you could use different texture maps and blend between them.