Creating Animations with Clutter

Matthew Allum

<mallum@openedhand.com>

Basic Animations
Timelines
Behaviours
Effects
Conclusion

With Clutter using hardware accelration for graphics rendering, complex and fast animations are possible. This chapter describes basic techniques and the utilities Clutter provides in aiding animation creation.

Basic Animations

The most basic way to create animations with Clutter is via the use of g_timeout_add(). This enables a callback function to be called at a defined interval. The callback function can then modify actors visual properties as to produce an animation.

Example 8.

Simple Rotation...

struct RotationClosure {
  ClutterActor *actor;
  ClutterFixed final_angle;
  ClutterFixed current_angle;
};

static gboolean
rotate_actor (gpointer data)
{
  RotationClosure *clos = data;

  clutter_actor_set_rotationx (clos->actor, clos->current_angle, 0, 0, 0);

  clos->current_angle += CFX_ONE;

  if (clos->current_angle == clos->final_angle)
    return FALSE;

  return TRUE;
}

...
  RotationClosure clos = { NULL, }

  clos.actor = an_actor;
  clos.final_angle = CLUTTER_FLOAT_TO_FIXED (360.0);
  clos.current_angle = 0;

  g_timeout_add (1000 / 360, /* fps to interval in milliseconds */
                 rotate_actor,
                 &clos);

Priorities

%G_PRIORITY_DEFAULT should always be used as the timeouts priority (in case of g_timeout_add_full()) as not to intefere with Clutter's scheduling of repaints and input event handling.