// generic world to screen,
  // derivate of ogc world to screen.
  virtual bool __cdecl worldToScreen(vector_3d worldCoord, int *xy);
  virtual bool __cdecl worldToScreen(vector_3d worldCoord, int *x, int *y);
  virtual bool __cdecl worldToScreen(vector_3d worldCoord, vector_3d screenCoord /*z=0*/);
public:
  // must be updated to use worldToScreen
  // info about your player
  vector_3d actual_vieworg;
  angles_3d actual_viewang;
  float     actual_fov;