limited of GLSL in blender

Hi :slight_smile:
I find a lot of tut for GLSL and I see GLSL can make refract and shadow and a lot more in game engine so can blender accept that or have limited ?
This same EX and tut for GLSL

unfortunately, the GLSL in blender is limited. AFAIK, shadows and refraction are not possible with the current implementation.

and anther staff ?
or blender have list what can do and what not ?