Nonvirtual member functions

• int num(void) - returns current number of frames in the list.
• int frame(void) - returns the current frame number.
• int is_current(void) - returns whether there is a current frame.
• Timestep *current(void) - returns the current frame itself, or NULL if there is none.
• Timestep *item(int) - returns the Nth frame.
• void goto_frame(int) - jump to the specified frame.
• int has_frame_changed(void) - returns whether the current frame has been changed recently.
• void delete_animation(void) - deletes all the currently stored frames.
• void delete_frame(int) - delete the Nth frame.
• int append_frame(Timestep *) - adds the given frame to the end of the animation list (or wherever has been previously determined for it to be placed).
• int anim_update(void) - updates the current position of the animation in the list, based on the current animation mode, and returns the index of the new current frame. Also sets the flags indicating whether the frame has changed. This is called during each call to prepare in the Molecule object.
• void append_end(void) - indicate to append the next frame at the end of the list.
• void append_start(void) - indicate to append the next frame at the start of the list.
• void append_after(int) - indicate to append the next frame after the specified frame.
• void append_before(int) - indicate to append the next frame before the specified frame.
• void skip(int) - set the current frame skip rate (the increment by which the current frame pointer is changed).
• int skip(void) - return the current frame skip rate.
• void anim_dir(AnimDir) - set the current animation direction.
• AnimDir anim_dir(void) - return the animation direction.
• void anim_style(AnimStyle) - set the animation method.
• AnimSTyle anim_style(void) - return the animation method.
• float speed(float) - set the speed of the animation.
• float speed(void) - return the current animation speed.