   opacity/alpha map
  I’ve created our house in 3ds max and used panda to export .x file, then loaded the scene in XNA, I’ve set a mouse camera with that so the I can walk and look.Now I want to add some windows and trees, I need the opacity map on meshes, is fx composer used to assign opacity maps? I really can’t work with fx composer 2, all I do is to import the .x file and see the textures. I looked into the documentation but it’s nowhere, also I failed surfing web (I also watched the introductory video for fx composer from nvidia, it shows how to apply an effect and shader to a material)Further I need to set some lights(currently I’m using EnableDefaultLighting) and collision detection, lights can be done in fx composer. I’ll look for collision later, but I also watched the make a game in 60 minutes from xna.com and I know about making a sphere around the meshes for collide.   
  I'm not really familiar with fx composer but opacity mapping in rasterization is no cake walk, it's not like raytracing where you can simply check the opacity value and have the ray continue through to whats behind it if its transparent.  rasterization transforms the geometry first, discards occluded geometry, then you dont see opacity value until you're in the pixel shader...so you know its transparent, but you dont know whats behind it.  therefore you have to render and accumulate into a buffer each transparent thing in a depth sorted order.   ;  in fx composer or from nvidia website I can download pre_texture shader and when you load it shows a texture as the background, there are shaders with more advanced functionality like edge detection, so I guess there must be a shader which sets an alpha maphttp://developer.download.nvidia.com/shaderlibrary/webpages/shader_library.htmlhere are many shader which I still could not find the suitable for my problem;  somebody assist please   