i am having a problem with the texture size in this tutorial the size is 256*256 but it would be good if i could use the same resolution like in the video, even if i try to use 512*512 it doesn''t work (my video is 640*480) thanxx for any help

You can change the size, (it works on my computer) but it isn''t guarenteed to work on all hardware. (it doesn''t work here at my school for example.) Otherwise (I haven''t seen the source yet, so I don''t know how doable this is) you can use a couple textures. Be sure to set GL_TEXTURE_WRAP_S GL_TEXTURE_WRAP_T to GL_CLAMP with glTexParameteri so that you don''t see funny things from the other side of the texture when you shouldn''t. That happened in SystemShock(tm), and it bugged the hell out of me.