   Transparent surfaces and performance
  I would like to ask how much using some transparent surfaces affects the speed of your game. I have four trasparent surfaces in a certain area of the map. When I point the camera towards those transparet surfaces the FPS rate drops with at least one third.I was thinking to use some textures with an alpha channel to imitate the shadows beneath the objects. I would have to draw about 50 to 100 shadows wich would be really slow if the transparent surfaces are as expensive as I think.   