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Show how to animate an actor using a ClutterPathConstraint. This demonstrates how to get effects similar to ClutterPathBehaviour with the modern animation APIs. Includes 3 examples: 1) Simple ClutterPathConstraint used with implicit animations 2) ClutterPathConstraint used to simulate circular animation, using ClutterAnimator 3) Creating simple curved path animations with non-linear easing
129 lines
3.9 KiB
C
129 lines
3.9 KiB
C
#include <stdlib.h>
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#include <clutter/clutter.h>
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#define STAGE_SIDE 400.0
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static const ClutterColor stage_color = { 0x33, 0x33, 0x55, 0xff };
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static const ClutterColor red_color = { 0xff, 0x00, 0x00, 0xff };
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/* Build a "circular" path out of 4 Bezier curves
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*
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* code modified from
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* http://git.clutter-project.org/dax/tree/dax/dax-traverser-clutter.c#n328
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*
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* see http://www.whizkidtech.redprince.net/bezier/circle/
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* for further explanation
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*/
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static ClutterPath *
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build_circular_path (gfloat cx,
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gfloat cy,
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gfloat r)
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{
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ClutterPath *path;
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static gfloat kappa = 4 * (G_SQRT2 - 1) / 3;
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path = clutter_path_new ();
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clutter_path_add_move_to (path, cx + r, cy);
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clutter_path_add_curve_to (path,
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cx + r, cy + r * kappa,
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cx + r * kappa, cy + r,
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cx, cy + r);
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clutter_path_add_curve_to (path,
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cx - r * kappa, cy + r,
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cx - r, cy + r * kappa,
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cx - r, cy);
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clutter_path_add_curve_to (path,
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cx - r, cy - r * kappa,
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cx - r * kappa, cy - r,
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cx, cy - r);
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clutter_path_add_curve_to (path,
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cx + r * kappa, cy - r,
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cx + r, cy - r * kappa,
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cx + r, cy);
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clutter_path_add_close (path);
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return path;
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}
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static gboolean
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key_pressed_cb (ClutterActor *actor,
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ClutterEvent *event,
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gpointer user_data)
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{
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ClutterTimeline *timeline = CLUTTER_TIMELINE (user_data);
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if (!clutter_timeline_is_playing (timeline))
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clutter_timeline_start (timeline);
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return TRUE;
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}
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int
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main (int argc,
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char *argv[])
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{
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ClutterPath *path;
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ClutterConstraint *constraint;
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ClutterAnimator *animator;
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ClutterTimeline *timeline;
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ClutterActor *stage;
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ClutterActor *rectangle;
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clutter_init (&argc, &argv);
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stage = clutter_stage_new ();
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clutter_actor_set_size (stage, STAGE_SIDE, STAGE_SIDE);
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clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
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g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);
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rectangle = clutter_rectangle_new_with_color (&red_color);
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clutter_actor_set_size (rectangle, STAGE_SIDE / 8, STAGE_SIDE / 8);
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clutter_actor_set_position (rectangle,
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STAGE_SIDE / 2,
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STAGE_SIDE / 2);
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clutter_container_add_actor (CLUTTER_CONTAINER (stage),
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rectangle);
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/* set up a path and make a constraint with it */
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path = build_circular_path (STAGE_SIDE / 2,
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STAGE_SIDE / 2,
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STAGE_SIDE / 4);
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constraint = clutter_path_constraint_new (path, 0.0);
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/* apply the constraint to the rectangle; note that there
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* is no need to name the constraint, as we will be animating
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* the constraint's offset property directly using ClutterAnimator
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*/
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clutter_actor_add_constraint (rectangle, constraint);
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/* animation to animate the path offset */
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animator = clutter_animator_new ();
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clutter_animator_set_duration (animator, 5000);
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/* use ClutterAnimator to animate the constraint directly */
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clutter_animator_set (animator,
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constraint, "offset", CLUTTER_LINEAR, 0.0, 0.0,
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constraint, "offset", CLUTTER_LINEAR, 1.0, 1.0,
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NULL);
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timeline = clutter_animator_get_timeline (animator);
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clutter_timeline_set_loop (timeline, TRUE);
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clutter_timeline_set_auto_reverse (timeline, TRUE);
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g_signal_connect (stage,
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"key-press-event",
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G_CALLBACK (key_pressed_cb),
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timeline);
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clutter_actor_show (stage);
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clutter_main ();
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/* clean up */
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g_object_unref (animator);
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return EXIT_SUCCESS;
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}
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