RTS Camera Movement - This camera control system functions like in any professional RTS game. You move the mouse close to the edge and the screen moves, move it closer and the scre

This code works by seeing if the mouse is close to the edge (within two different distances) this is worked out as a value relative to the screen width and height. Left and right movement is simple enough using the move camera left/right commands.
Moving the camera forward/backward and maintain the angle the camera faces down can be done easily without any vector work. You just angle the camera to face directly forward as is default (angle camera 0), move it the required speed, then angle it back to the original angle.

                                    ` This code was downloaded from The Game Creators
                                    ` It is reproduced here with full permission
                                    ` http://www.thegamecreators.com
                                    
                                    REM Global variables to be declared before rest of program

global cam_speed# = 1.0 `camera speed
global cam_height# = 30 `camera's height above the terrain
global mat_num = 1 `matrix number



FUNCTION camera_control()
   if mousex()>screen width() - (screen width()/50) `slow right
      move camera right (cam_speed#/2)
   endif
   if mousex()<screen width()/50 `slow left
      move camera left (cam_speed#/2)
   endif
   if mousex()>screen width() - (screen width()/100) `fast right
      move camera right cam_speed#
   endif
   if mousex()< screen width()/100 `fast left
      move camera left cam_speed#
   endif
   if mousey()>screen height() - (screen height()/25) `slow backward
      cx=camera angle x()
      xrotate camera 0
      move camera -(cam_speed#/2)
      xrotate camera cx
   endif
   if mousey()<screen height()/25 `slow forward
      cx=camera angle x()
      xrotate camera 0
      move camera (cam_speed#/2)
      xrotate camera cx
   endif
   if mousey()>screen height() - (screen height()/100) `fast backward
      cx=camera angle x()
      xrotate camera 0
      move camera -cam_speed#
      xrotate camera cx
   endif
   if mousey()<screen height()/100 `fast forward
      cx=camera angle x()
      xrotate camera 0
      move camera cam_speed#
      xrotate camera cx
   endif
   position camera camera position x(),(get ground height(mat_num,camera position x(),camera position z())+cam_height#),camera position z()
ENDFUNCTION