leonn, for the oil painting effect I don’t really think this is the best solution. If the image is static (e.g. a picture) then a simple GLSL brush strokes shader would do the trick.
kevincorrigan - reflection and refraction rendering no, you can use this in Multitexture mode. The shader that processes the water surface and textures - yes it is a GLSL shader.
Ace Dragon, awesome! I was very interested in this thing once I saw it in CryEngine2. Thanks for the link, I will try to make it work in BGE.
I think it is not the shader that is causing the problem, but perhaps the texture rendering or camera setup… I have to do a deeper research.