mutter/clutter/tests/interactive/test-cogl-offscreen.c

#include <glib.h>
#include <gmodule.h>
#include <stdlib.h>
#include <clutter/clutter.h>
#include <cogl/cogl.h>

/* Coglbox declaration
 *--------------------------------------------------*/

G_BEGIN_DECLS

#define TEST_TYPE_COGLBOX test_coglbox_get_type()

#define TEST_COGLBOX(obj) \
  (G_TYPE_CHECK_INSTANCE_CAST ((obj), \
  TEST_TYPE_COGLBOX, TestCoglboxClass))

#define TEST_COGLBOX_CLASS(klass) \
  (G_TYPE_CHECK_CLASS_CAST ((klass), \
  TEST_TYPE_COGLBOX, TestCoglboxClass))

#define TEST_IS_COGLBOX(obj) \
  (G_TYPE_CHECK_INSTANCE_TYPE ((obj), \
  TEST_TYPE_COGLBOX))

#define TEST_IS_COGLBOX_CLASS(klass) \
  (G_TYPE_CHECK_CLASS_TYPE ((klass), \
  TEST_TYPE_COGLBOX))

#define TEST_COGLBOX_GET_CLASS(obj) \
  (G_TYPE_INSTANCE_GET_CLASS ((obj), \
  TEST_TYPE_COGLBOX, TestCoglboxClass))

typedef struct _TestCoglbox        TestCoglbox;
typedef struct _TestCoglboxClass   TestCoglboxClass;
typedef struct _TestCoglboxPrivate TestCoglboxPrivate;

struct _TestCoglbox
{
  ClutterActor           parent;

  /*< private >*/
  TestCoglboxPrivate *priv;
};

struct _TestCoglboxClass
{
  ClutterActorClass parent_class;

  /* padding for future expansion */
  void (*_test_coglbox1) (void);
  void (*_test_coglbox2) (void);
  void (*_test_coglbox3) (void);
  void (*_test_coglbox4) (void);
};

static GType test_coglbox_get_type (void) G_GNUC_CONST;

G_END_DECLS

/* Coglbox private declaration
 *--------------------------------------------------*/

struct _TestCoglboxPrivate
{
  CoglHandle texhand_id;
  CoglHandle texture_id;
  CoglHandle offscreen_id;
};

G_DEFINE_TYPE_WITH_PRIVATE (TestCoglbox, test_coglbox, CLUTTER_TYPE_ACTOR);

#define TEST_COGLBOX_GET_PRIVATE(obj) \
(G_TYPE_INSTANCE_GET_PRIVATE ((obj), TEST_TYPE_COGLBOX, TestCoglboxPrivate))

/* Coglbox implementation
 *--------------------------------------------------*/

static void
test_coglbox_paint (ClutterActor *self)
{
  TestCoglboxPrivate *priv = TEST_COGLBOX_GET_PRIVATE (self);
  gfloat texcoords[4] = { 0, 0, 1, 1 };
  CoglHandle material;

  cogl_set_source_color4ub (0x66, 0x66, 0xdd, 0xff);
  cogl_rectangle (0, 0, 400, 400);

  cogl_set_source_texture (priv->texhand_id);
  cogl_rectangle_with_texture_coords (0, 0,
                                      400, 400,
                                      0, 0,
                                      6, 6);

  cogl_push_framebuffer (priv->offscreen_id);

  cogl_set_source_color4ub (0xff, 0, 0, 0xff);
  cogl_rectangle (20, 20, 20 + 100, 20 + 100);

  cogl_set_source_color4ub (0, 0xff, 0, 0xff);
  cogl_rectangle (80, 80, 80 + 100, 80 + 100);

  cogl_pop_framebuffer ();

  material = cogl_material_new ();
  cogl_material_set_color4ub (material, 0x88, 0x88, 0x88, 0x88);
  cogl_material_set_layer (material, 0, priv->texture_id);
  cogl_set_source (material);
  cogl_rectangle_with_texture_coords (100, 100,
                                      300, 300,
                                      texcoords[0],
                                      texcoords[1],
                                      texcoords[2],
                                      texcoords[3]);
}

static void
test_coglbox_finalize (GObject *object)
{
  G_OBJECT_CLASS (test_coglbox_parent_class)->finalize (object);
}

static void
test_coglbox_dispose (GObject *object)
{
  TestCoglboxPrivate *priv;

  priv = TEST_COGLBOX_GET_PRIVATE (object);

  cogl_handle_unref (priv->texture_id);
  cogl_handle_unref (priv->offscreen_id);

  G_OBJECT_CLASS (test_coglbox_parent_class)->dispose (object);
}

/* A newly created Cogl framebuffer will be initialized with a
 * viewport covering the size of the viewport i.e. equavalent to:
 *
 * calling cogl_framebuffer_set_viewport (
 *                                fb,
 *                                0, 0,
 *                                cogl_framebuffer_get_viewport_width (fb),
 *                                cogl_framebuffer_get_viewport_width (fb));
 *
 * The projection matrix will be an identity matrix.
 *
 * The modelview matrix will be an identity matrix, and this will
 * create a coordinate system - like OpenGL - with the viewport
 * being mapped to a unit cube with the origin (0, 0, 0) in the
 * center, x, y and z ranging from -1 to 1 with (-1, -1) being top
 * left and (1, 1) bottom right.
 *
 * This sets up a Clutter like coordinate system for a Cogl
 * framebuffer
 */
void
setup_viewport (unsigned int width,
                unsigned int height,
                float fovy,
                float aspect,
                float z_near,
                float z_far)
{
  float z_camera;
  CoglMatrix projection_matrix;
  CoglMatrix mv_matrix;

  cogl_set_viewport (0, 0, width, height);

  /* For Ortho projection.
   * _cogl_matrix_stack_ortho (projection_stack, 0, width, 0,  height, -1, 1);
   */

  cogl_perspective (fovy, aspect, z_near, z_far);

  /*
   * In theory, we can compute the camera distance from screen as:
   *
   *   0.5 * tan (FOV)
   *
   * However, it's better to compute the z_camera from our projection
   * matrix so that we get a 1:1 mapping at the screen distance. Consider
   * the upper-left corner of the screen. It has object coordinates
   * (0,0,0), so by the transform below, ends up with eye coordinate
   *
   *   x_eye = x_object / width - 0.5 = - 0.5
   *   y_eye = (height - y_object) / width - 0.5 = 0.5
   *   z_eye = z_object / width - z_camera = - z_camera
   *
   * From cogl_perspective(), we know that the projection matrix has
   * the form:
   *
   *  (x, 0,  0, 0)
   *  (0, y,  0, 0)
   *  (0, 0,  c, d)
   *  (0, 0, -1, 0)
   *
   * Applied to the above, we get clip coordinates of
   *
   *  x_clip = x * (- 0.5)
   *  y_clip = y * 0.5
   *  w_clip = - 1 * (- z_camera) = z_camera
   *
   * Dividing through by w to get normalized device coordinates, we
   * have, x_nd = x * 0.5 / z_camera, y_nd = - y * 0.5 / z_camera.
   * The upper left corner of the screen has normalized device coordinates,
   * (-1, 1), so to have the correct 1:1 mapping, we have to have:
   *
   *   z_camera = 0.5 * x = 0.5 * y
   *
   * If x != y, then we have a non-uniform aspect ration, and a 1:1 mapping
   * doesn't make sense.
   */

  cogl_get_projection_matrix (&projection_matrix);
  z_camera = 0.5 * projection_matrix.xx;

  cogl_matrix_init_identity (&mv_matrix);
  cogl_matrix_translate (&mv_matrix, -0.5f, -0.5f, -z_camera);
  cogl_matrix_scale (&mv_matrix, 1.0f / width, -1.0f / height, 1.0f / width);
  cogl_matrix_translate (&mv_matrix, 0.0f, -1.0 * height, 0.0f);
  cogl_set_modelview_matrix (&mv_matrix);
}

static void
test_coglbox_map (ClutterActor *actor)
{
  TestCoglboxPrivate *priv = TEST_COGLBOX_GET_PRIVATE (actor);
  ClutterActor *stage;
  ClutterPerspective perspective;
  float stage_width;
  float stage_height;

  CLUTTER_ACTOR_CLASS (test_coglbox_parent_class)->map (actor);

  printf ("Creating offscreen\n");
  priv->offscreen_id = cogl_offscreen_new_to_texture (priv->texture_id);

  stage = clutter_actor_get_stage (actor);
  clutter_stage_get_perspective (CLUTTER_STAGE (stage), &perspective);
  clutter_actor_get_size (stage, &stage_width, &stage_height);

  cogl_push_framebuffer (priv->offscreen_id);

  setup_viewport (stage_width, stage_height,
                  perspective.fovy,
                  perspective.aspect,
                  perspective.z_near,
                  perspective.z_far);

  cogl_pop_framebuffer ();

  if (priv->offscreen_id == COGL_INVALID_HANDLE)
    printf ("Failed creating offscreen to texture!\n");
}

static void
test_coglbox_init (TestCoglbox *self)
{
  TestCoglboxPrivate *priv;
  gchar *file;

  self->priv = priv = TEST_COGLBOX_GET_PRIVATE(self);

  printf ("Loading redhand.png\n");
  file = g_build_filename (TESTS_DATADIR, "redhand.png", NULL);
  priv->texhand_id = cogl_texture_new_from_file (file,
                                                 COGL_TEXTURE_NONE,
						 COGL_PIXEL_FORMAT_ANY,
                                                 NULL);
  g_free (file);

  printf ("Creating texture with size\n");
  priv->texture_id = cogl_texture_new_with_size (200, 200,
                                                 COGL_TEXTURE_NONE,
						 COGL_PIXEL_FORMAT_RGB_888);

  if (priv->texture_id == COGL_INVALID_HANDLE)
    printf ("Failed creating texture with size!\n");
}

static void
test_coglbox_class_init (TestCoglboxClass *klass)
{
  GObjectClass      *gobject_class = G_OBJECT_CLASS (klass);
  ClutterActorClass *actor_class   = CLUTTER_ACTOR_CLASS (klass);

  gobject_class->finalize     = test_coglbox_finalize;
  gobject_class->dispose      = test_coglbox_dispose;

  actor_class->map            = test_coglbox_map;
  actor_class->paint          = test_coglbox_paint;
}

static ClutterActor*
test_coglbox_new (void)
{
  return g_object_new (TEST_TYPE_COGLBOX, NULL);
}

G_MODULE_EXPORT int
test_cogl_offscreen_main (int argc, char *argv[])
{
  ClutterActor *stage;
  ClutterActor *coglbox;

  if (clutter_init (&argc, &argv) != CLUTTER_INIT_SUCCESS)
    return 1;

  /* Stage */
  stage = clutter_stage_new ();
  clutter_actor_set_size (stage, 400, 400);
  clutter_stage_set_title (CLUTTER_STAGE (stage), "Cogl Offscreen Buffers");
  g_signal_connect (stage, "destroy", G_CALLBACK (clutter_main_quit), NULL);

  /* Cogl Box */
  coglbox = test_coglbox_new ();
  clutter_container_add_actor (CLUTTER_CONTAINER (stage), coglbox);

  clutter_actor_show_all (stage);

  clutter_main ();

  return 0;
}

G_MODULE_EXPORT const char *
test_cogl_offscreen_describe (void)
{
  return "Offscreen buffer support in Cogl.";
}