   Simplest 3D-engine questions
  First at all, sorry for my bad english I''ve read many articles about game development, 3d graphics, know well Direct3D 8, etc. I''ve wrote many 2D games before. But when I''ve begin my work with the simplest 3d engine - for games like "vertical scroll" - I''ve got many questions without answers anywhere.1) Which structures are useful when I''m programming 3D animations? For example, I have a tank. Tank consists of 3 parts: a "mother" part, a "chain tracks" and a "tower with gun". Let''s  imagine each part has it''s own animation chains. Which format (in C++ - code!) should I use to describe the fraims in the chains?2) If I want to animate parts of the tank using transformations only like rotating, moving, etc. Should I use a script language to describe the animation in this way or you know any shorter way to describe this?3) Should I calculate and story all vertixes in video-memory for each frame in each chaing of each part of each objects? Of course, without repeating the same blocks of the same objects. How much vedio memory can I use for this if the game is shareware - 16 Mb? 32 Mb?4) How can I use hardware T&L without using shaders manually?5) How can I use for free (I mean money) 3ds-files? Is there any freeware libraries for using them? Maybe the answers about the animation in this way?Thank you all! 
  There are some links to free .3ds files on this site under resources.  Maybe there''s something there. ;  3dcafe.net has a large collection of .3ds files.