예제 #1
0
void
_mai_node_draw_recursive (MaiNode *self, CoglMatrix *acc_mtx)
{
  CoglPrimitive *to_draw;
  to_draw = nx_cogl_primitive_new (self->mesh_verts, self->mesh_indices, self->mesh_uvs);

  CoglMatrix cur_mtx;
  cogl_matrix_init_identity (&cur_mtx);
  cogl_matrix_multiply (&cur_mtx, &cur_mtx, acc_mtx);
  cogl_matrix_multiply (&cur_mtx, &cur_mtx, self->transformation);

  cogl_set_modelview_matrix (&cur_mtx);

  nx_cogl_primitive_draw (to_draw);

  cogl_object_unref (to_draw);

  int tmp1;
  for (tmp1=0; tmp1<self->children->len; ++tmp1)
    {
      MaiNode *child;
      child = g_mai_node_ptr_array_index (self->children, tmp1);
      _mai_node_draw_recursive (child, &cur_mtx);
    }
}
예제 #2
0
파일: mx-fade-effect.c 프로젝트: 3v1n0/mx
static void
mx_fade_effect_post_paint (ClutterEffect *effect)
{
  MxFadeEffectPrivate *priv = MX_FADE_EFFECT (effect)->priv;

  if (!priv->freeze_update)
    CLUTTER_EFFECT_CLASS (mx_fade_effect_parent_class)->post_paint (effect);
  else
    {
      CoglMatrix modelview;
      ClutterActor *actor, *stage;

      actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
      stage = clutter_actor_get_stage (actor);

      /* Set up the draw matrix so we draw the offscreen texture at the
       * absolute coordinates of the actor-box. We need to do this to
       * avoid transforming by the actor matrix twice, as when it's drawn
       * into the offscreen surface, it'll already be transformed.
       */
      cogl_push_matrix ();

      cogl_matrix_init_identity (&modelview);
      CLUTTER_ACTOR_CLASS (G_OBJECT_GET_CLASS (stage))->
        apply_transform (stage, &modelview);
      cogl_matrix_translate (&modelview, priv->x_offset, priv->y_offset, 0.f);
      cogl_set_modelview_matrix (&modelview);

      clutter_offscreen_effect_paint_target (CLUTTER_OFFSCREEN_EFFECT (effect));

      cogl_pop_matrix ();
    }
}
예제 #3
0
파일: csw.c 프로젝트: nOOb3167/Abcdef
void
_example_draw_at (int x, int y)
{
    cogl_set_source_color4ub ('\xFF', '1', '1', 255);
    cogl_ortho (0, 64, 0, 64, -5, 5);

    CoglMatrix idmtx;
    cogl_matrix_init_identity (&idmtx);
    cogl_set_modelview_matrix (&idmtx);

    cogl_rectangle (x+1, y+1, x-1, y-1);

    cogl_flush ();
}
예제 #4
0
void
mai_node_draw_recursive (MaiNode *self)
{
  CoglMatrix initial_mtx;
  cogl_matrix_init_identity (&initial_mtx);
  cogl_set_modelview_matrix (&initial_mtx);

  cogl_set_source_color4ub ('\x1', '\x1', '\xFF', 255);
  cogl_set_source_texture (g_testtex);
  cogl_ortho (0, 64, 0, 64, -1, 1);

  cogl_matrix_translate (&initial_mtx, 20.0f, 20.0f, 0.0f);
  cogl_matrix_scale (&initial_mtx, 5.0f, 5.0f, 1.0f);
  cogl_matrix_rotate(&initial_mtx, -90.0f, 1.0f, 0.0f, 0.0f);

  _mai_node_draw_recursive (self, &initial_mtx);

  cogl_flush ();
}
예제 #5
0
static void
paint (TestState *state)
{
  float stage_viewport[4];
  CoglMatrix stage_projection;
  CoglMatrix stage_modelview;

  paint_test_backface_culling (state);

  /*
   * Now repeat the test but rendered to an offscreen
   * framebuffer. Note that by default the conformance tests are
   * always run to an offscreen buffer but we might as well have this
   * check anyway in case it is being run with COGL_TEST_ONSCREEN=1
   */

  cogl_get_viewport (stage_viewport);
  cogl_get_projection_matrix (&stage_projection);
  cogl_get_modelview_matrix (&stage_modelview);

  cogl_push_framebuffer (state->offscreen);

  cogl_set_viewport (stage_viewport[0],
                     stage_viewport[1],
                     stage_viewport[2],
                     stage_viewport[3]);
  cogl_set_projection_matrix (&stage_projection);
  cogl_set_modelview_matrix (&stage_modelview);

  paint_test_backface_culling (state);

  cogl_pop_framebuffer ();

  /* Incase we want feedback of what was drawn offscreen we draw it
   * to the stage... */
  cogl_set_source_texture (state->offscreen_tex);
  cogl_rectangle (0, TEXTURE_RENDER_SIZE * 16,
                  stage_viewport[2],
                  stage_viewport[3] + TEXTURE_RENDER_SIZE * 16);

  validate_result (0);
  validate_result (16);
}
예제 #6
0
static void
_clutter_stage_wayland_repair_dirty(ClutterStageWayland *stage_wayland,
				       ClutterStage     *stage)
{
  CoglMaterial *outline = NULL;
  CoglHandle vbo;
  float vertices[8], texcoords[8];
  CoglMatrix modelview;
  cairo_region_t *dirty;
  cairo_rectangle_int_t rect;
  int i, count;
  float width, height;

  dirty = stage_wayland->back_buffer->dirty_region;
  stage_wayland->back_buffer->dirty_region = NULL;
  cairo_region_subtract (dirty, stage_wayland->repaint_region);
  width = stage_wayland->allocation.width;
  height = stage_wayland->allocation.height;
  
  /* If this is the first time we render, there is no front buffer to
   * copy back from, but then the dirty region not covered by the
   * repaint should be empty, because we repaint the entire stage.
   *
   * assert(stage_wayland->front_buffer != NULL) ||
   *   cairo_region_is_empty(dirty);
   *
   * FIXME: in test-rotate, the stage never queues a full repaint
   * initially, it's restricted to the paint box of it's rotating
   * children.
   */

  if (!stage_wayland->front_buffer)
    return;

  outline = cogl_material_new ();
  cogl_material_set_layer (outline, 0, stage_wayland->front_buffer->tex);
  count = cairo_region_num_rectangles (dirty);

  for (i = 0; i < count; i++)
    {
      cairo_region_get_rectangle (dirty, i, &rect);
      vbo = cogl_vertex_buffer_new (4);

      vertices[0] = rect.x - 1;
      vertices[1] = rect.y - 1;
      vertices[2] = rect.x + rect.width + 1;
      vertices[3] = rect.y - 1;
      vertices[4] = rect.x + rect.width + 1;
      vertices[5] = rect.y + rect.height + 1;
      vertices[6] = rect.x - 1;
      vertices[7] = rect.y + rect.height + 1;

      cogl_vertex_buffer_add (vbo,
			      "gl_Vertex",
			      2, /* n_components */
			      COGL_ATTRIBUTE_TYPE_FLOAT,
			      FALSE, /* normalized */
			      0, /* stride */
			      vertices);

      texcoords[0] = vertices[0] / width;
      texcoords[1] = vertices[1] / height;
      texcoords[2] = vertices[2] / width;
      texcoords[3] = vertices[3] / height;
      texcoords[4] = vertices[4] / width;
      texcoords[5] = vertices[5] / height;
      texcoords[6] = vertices[6] / width;
      texcoords[7] = vertices[7] / height;

      cogl_vertex_buffer_add (vbo,
			      "gl_MultiTexCoord0",
			      2, /* n_components */
			      COGL_ATTRIBUTE_TYPE_FLOAT,
			      FALSE, /* normalized */
			      0, /* stride */
			      texcoords);

      cogl_vertex_buffer_submit (vbo);

      cogl_push_matrix ();
      cogl_matrix_init_identity (&modelview);
      _clutter_actor_apply_modelview_transform (CLUTTER_ACTOR (stage),
						&modelview);
      cogl_set_modelview_matrix (&modelview);
      cogl_set_source (outline);
      cogl_vertex_buffer_draw (vbo, COGL_VERTICES_MODE_TRIANGLE_FAN,
			       0 , 4);
      cogl_pop_matrix ();
      cogl_object_unref (vbo);
    }

  cairo_region_destroy (dirty);
}
예제 #7
0
static void
clutter_stage_glx_redraw (ClutterStageWindow *stage_window)
{
  ClutterBackendX11 *backend_x11;
  ClutterBackendGLX *backend_glx;
  ClutterStageX11 *stage_x11;
  ClutterStageGLX *stage_glx;
  GLXDrawable drawable;
  unsigned int video_sync_count;
  gboolean may_use_clipped_redraw;
  gboolean use_clipped_redraw;

  CLUTTER_STATIC_TIMER (painting_timer,
                        "Redrawing", /* parent */
                        "Painting actors",
                        "The time spent painting actors",
                        0 /* no application private data */);
  CLUTTER_STATIC_TIMER (swapbuffers_timer,
                        "Redrawing", /* parent */
                        "glXSwapBuffers",
                        "The time spent blocked by glXSwapBuffers",
                        0 /* no application private data */);
  CLUTTER_STATIC_TIMER (blit_sub_buffer_timer,
                        "Redrawing", /* parent */
                        "glx_blit_sub_buffer",
                        "The time spent in _glx_blit_sub_buffer",
                        0 /* no application private data */);

  stage_x11 = CLUTTER_STAGE_X11 (stage_window);
  if (stage_x11->xwin == None)
    return;

  stage_glx = CLUTTER_STAGE_GLX (stage_window);

  backend_x11 = stage_x11->backend;
  backend_glx = CLUTTER_BACKEND_GLX (backend_x11);

  CLUTTER_TIMER_START (_clutter_uprof_context, painting_timer);

  if (G_LIKELY (backend_glx->can_blit_sub_buffer) &&
      /* NB: a zero width redraw clip == full stage redraw */
      stage_glx->bounding_redraw_clip.width != 0 &&
      /* some drivers struggle to get going and produce some junk
       * frames when starting up... */
      G_LIKELY (stage_glx->frame_count > 3) &&
      /* While resizing a window clipped redraws are disabled to avoid
       * artefacts. See clutter-event-x11.c:event_translate for a
       * detailed explanation */
      G_LIKELY (stage_x11->clipped_redraws_cool_off == 0))
    {
      may_use_clipped_redraw = TRUE;
    }
  else
    may_use_clipped_redraw = FALSE;

  if (may_use_clipped_redraw &&
      G_LIKELY (!(clutter_paint_debug_flags &
                  CLUTTER_DEBUG_DISABLE_CLIPPED_REDRAWS)))
    use_clipped_redraw = TRUE;
  else
    use_clipped_redraw = FALSE;

  if (use_clipped_redraw)
    {
      CLUTTER_NOTE (CLIPPING,
                    "Stage clip pushed: x=%d, y=%d, width=%d, height=%d\n",
                    stage_glx->bounding_redraw_clip.x,
                    stage_glx->bounding_redraw_clip.y,
                    stage_glx->bounding_redraw_clip.width,
                    stage_glx->bounding_redraw_clip.height);
      cogl_clip_push_window_rectangle (stage_glx->bounding_redraw_clip.x,
                                       stage_glx->bounding_redraw_clip.y,
                                       stage_glx->bounding_redraw_clip.width,
                                       stage_glx->bounding_redraw_clip.height);
      _clutter_stage_do_paint (stage_x11->wrapper,
                               &stage_glx->bounding_redraw_clip);
      cogl_clip_pop ();
    }
  else
    {
      CLUTTER_NOTE (CLIPPING, "Unclipped stage paint\n");
      _clutter_stage_do_paint (stage_x11->wrapper, NULL);
    }

  if (may_use_clipped_redraw &&
      G_UNLIKELY ((clutter_paint_debug_flags & CLUTTER_DEBUG_REDRAWS)))
    {
      static CoglMaterial *outline = NULL;
      ClutterGeometry *clip = &stage_glx->bounding_redraw_clip;
      ClutterActor *actor = CLUTTER_ACTOR (stage_x11->wrapper);
      CoglHandle vbo;
      float x_1 = clip->x;
      float x_2 = clip->x + clip->width;
      float y_1 = clip->y;
      float y_2 = clip->y + clip->height;
      float quad[8] = {
        x_1, y_1,
        x_2, y_1,
        x_2, y_2,
        x_1, y_2
      };
      CoglMatrix modelview;

      if (outline == NULL)
        {
          outline = cogl_material_new ();
          cogl_material_set_color4ub (outline, 0xff, 0x00, 0x00, 0xff);
        }

      vbo = cogl_vertex_buffer_new (4);
      cogl_vertex_buffer_add (vbo,
                              "gl_Vertex",
                              2, /* n_components */
                              COGL_ATTRIBUTE_TYPE_FLOAT,
                              FALSE, /* normalized */
                              0, /* stride */
                              quad);
      cogl_vertex_buffer_submit (vbo);

      cogl_push_matrix ();
      cogl_matrix_init_identity (&modelview);
      _clutter_actor_apply_modelview_transform (actor, &modelview);
      cogl_set_modelview_matrix (&modelview);
      cogl_set_source (outline);
      cogl_vertex_buffer_draw (vbo, COGL_VERTICES_MODE_LINE_LOOP,
                               0 , 4);
      cogl_pop_matrix ();
      cogl_object_unref (vbo);
    }

  cogl_flush ();
  CLUTTER_TIMER_STOP (_clutter_uprof_context, painting_timer);

  drawable = stage_glx->glxwin
           ? stage_glx->glxwin
           : stage_x11->xwin;

  /* If we might ever use _clutter_backend_glx_blit_sub_buffer then we
   * always need to keep track of the video_sync_count so that we can
   * throttle blits.
   *
   * Note: we get the count *before* we issue any glXCopySubBuffer or
   * blit_sub_buffer request in case the count would go up before
   * returning control to us.
   */
  if (backend_glx->can_blit_sub_buffer && backend_glx->get_video_sync)
    backend_glx->get_video_sync (&video_sync_count);

  /* push on the screen */
  if (use_clipped_redraw)
    {
      ClutterGeometry *clip = &stage_glx->bounding_redraw_clip;
      ClutterGeometry copy_area;
      ClutterActor *actor;

      CLUTTER_NOTE (BACKEND,
                    "_glx_blit_sub_buffer (window: 0x%lx, "
                                          "x: %d, y: %d, "
                                          "width: %d, height: %d)",
                    (unsigned long) drawable,
                    stage_glx->bounding_redraw_clip.x,
                    stage_glx->bounding_redraw_clip.y,
                    stage_glx->bounding_redraw_clip.width,
                    stage_glx->bounding_redraw_clip.height);

      /* XXX: It seems there will be a race here in that the stage
       * window may be resized before glXCopySubBufferMESA is handled
       * and so we may copy the wrong region. I can't really see how
       * we can handle this with the current state of X but at least
       * in this case a full redraw should be queued by the resize
       * anyway so it should only exhibit temporary artefacts.
       */
      actor = CLUTTER_ACTOR (stage_x11->wrapper);
      copy_area.y = clutter_actor_get_height (actor)
                  - clip->y
                  - clip->height;
      copy_area.x = clip->x;
      copy_area.width = clip->width;
      copy_area.height = clip->height;

      /* glXCopySubBufferMESA and glBlitFramebuffer are not integrated
       * with the glXSwapIntervalSGI mechanism which we usually use to
       * throttle the Clutter framerate to the vertical refresh and so
       * we have to manually wait for the vblank period...
       */

      /* Here 'is_synchronized' only means that the blit won't cause a
       * tear, ie it won't prevent multiple blits per retrace if they
       * can all be performed in the blanking period. If that's the
       * case then we still want to use the vblank sync menchanism but
       * we only need it to throttle redraws.
       */
      if (!backend_glx->blit_sub_buffer_is_synchronized)
        {
          /* XXX: note that glXCopySubBuffer, at least for Intel, is
           * synchronized with the vblank but glBlitFramebuffer may
           * not be so we use the same scheme we do when calling
           * glXSwapBuffers without the swap_control extension and
           * call glFinish () before waiting for the vblank period.
           *
           * See where we call glXSwapBuffers for more details.
           */
          glFinish ();
          wait_for_vblank (backend_glx);
        }
      else if (backend_glx->get_video_sync)
        {
          /* If we have the GLX_SGI_video_sync extension then we can
           * be a bit smarter about how we throttle blits by avoiding
           * any waits if we can see that the video sync count has
           * already progressed. */
          if (backend_glx->last_video_sync_count == video_sync_count)
            wait_for_vblank (backend_glx);
        }
      else
        wait_for_vblank (backend_glx);

      CLUTTER_TIMER_START (_clutter_uprof_context, blit_sub_buffer_timer);
      _clutter_backend_glx_blit_sub_buffer (backend_glx,
                                            drawable,
                                            copy_area.x,
                                            copy_area.y,
                                            copy_area.width,
                                            copy_area.height);
      CLUTTER_TIMER_STOP (_clutter_uprof_context, blit_sub_buffer_timer);
    }
  else
    {
      CLUTTER_NOTE (BACKEND, "glXSwapBuffers (display: %p, window: 0x%lx)",
                    backend_x11->xdpy,
                    (unsigned long) drawable);

      /* If we have GLX swap buffer events then glXSwapBuffers will return
       * immediately and we need to track that there is a swap in
       * progress... */
      if (clutter_feature_available (CLUTTER_FEATURE_SWAP_EVENTS))
        stage_glx->pending_swaps++;

      if (backend_glx->vblank_type != CLUTTER_VBLANK_GLX_SWAP &&
          backend_glx->vblank_type != CLUTTER_VBLANK_NONE)
        {
          /* If we are going to wait for VBLANK manually, we not only
           * need to flush out pending drawing to the GPU before we
           * sleep, we need to wait for it to finish. Otherwise, we
           * may end up with the situation:
           *
           *        - We finish drawing      - GPU drawing continues
           *        - We go to sleep         - GPU drawing continues
           * VBLANK - We call glXSwapBuffers - GPU drawing continues
           *                                 - GPU drawing continues
           *                                 - Swap buffers happens
           *
           * Producing a tear. Calling glFinish() first will cause us
           * to properly wait for the next VBLANK before we swap. This
           * obviously does not happen when we use _GLX_SWAP and let
           * the driver do the right thing
           */
          glFinish ();

          wait_for_vblank (backend_glx);
        }

      CLUTTER_TIMER_START (_clutter_uprof_context, swapbuffers_timer);
      glXSwapBuffers (backend_x11->xdpy, drawable);
      CLUTTER_TIMER_STOP (_clutter_uprof_context, swapbuffers_timer);

      _cogl_swap_buffers_notify ();
    }

  backend_glx->last_video_sync_count = video_sync_count;

  /* reset the redraw clipping for the next paint... */
  stage_glx->initialized_redraw_clip = FALSE;

  stage_glx->frame_count++;
}
예제 #8
0
static void
on_paint (ClutterActor *actor, void *state)
{
  float saved_viewport[4];
  CoglMatrix saved_projection;
  CoglMatrix projection;
  CoglMatrix modelview;
  guchar *data;
  CoglHandle tex;
  CoglHandle offscreen;
  CoglColor black;
  float x0;
  float y0;
  float width;
  float height;

  /* for clearing the offscreen framebuffer to black... */
  cogl_color_init_from_4ub (&black, 0x00, 0x00, 0x00, 0xff);

  cogl_get_viewport (saved_viewport);
  cogl_get_projection_matrix (&saved_projection);
  cogl_push_matrix ();

  cogl_matrix_init_identity (&projection);
  cogl_matrix_init_identity (&modelview);

  cogl_set_projection_matrix (&projection);
  cogl_set_modelview_matrix (&modelview);

  /* - Create a 100x200 viewport (i.e. smaller than the onscreen framebuffer)
   *   and position it a (20, 10) inside the framebuffer.
   * - Fill the whole viewport with a purple rectangle
   * - Verify that the framebuffer is black with a 100x200 purple rectangle at
   *   (20, 10)
   */
  cogl_set_viewport (20, /* x */
                     10, /* y */
                     100, /* width */
                     200); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  /* fill the viewport with purple.. */
  cogl_set_source_color4ub (0xff, 0x00, 0xff, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0xff, 0x00, 0xff);


  /* - Create a viewport twice the size of the onscreen framebuffer with
   *   a negative offset positioning it at (-20, -10) relative to the
   *   buffer itself.
   * - Draw a 100x200 green rectangle at (40, 20) within the viewport (which
   *   is (20, 10) within the framebuffer)
   * - Verify that the framebuffer is black with a 100x200 green rectangle at
   *   (20, 10)
   */
  cogl_set_viewport (-20, /* x */
                     -10, /* y */
                     FRAMEBUFFER_WIDTH * 2, /* width */
                     FRAMEBUFFER_HEIGHT * 2); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  /* draw a 100x200 green rectangle offset into the viewport such that its
   * top left corner should be found at (20, 10) in the offscreen buffer */
  /* (offset 40 pixels right from the left of the viewport) */
  x0 = -1.0f + (1.0f / FRAMEBUFFER_WIDTH) * 40.f;
  /* (offset 20 pixels down from the top of the viewport) */
  y0 = 1.0f - (1.0f / FRAMEBUFFER_HEIGHT) * 20.0f;
  width = (1.0f / FRAMEBUFFER_WIDTH) * 100;
  height = (1.0f / FRAMEBUFFER_HEIGHT) * 200;
  cogl_set_source_color4ub (0x00, 0xff, 0x00, 0xff);
  cogl_rectangle (x0, y0, x0 + width, y0 - height);
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0x00, 0xff, 0x00);


  /* - Create a 200x400 viewport and position it a (20, 10) inside the draw
   *   buffer.
   * - Push a 100x200 window space clip rectangle at (20, 10)
   * - Fill the whole viewport with a blue rectangle
   * - Verify that the framebuffer is black with a 100x200 blue rectangle at
   *   (20, 10)
   */
  cogl_set_viewport (20, /* x */
                     10, /* y */
                     200, /* width */
                     400); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  cogl_clip_push_window_rectangle (20, 10, 100, 200);
  /* fill the viewport with blue.. */
  cogl_set_source_color4ub (0x00, 0x00, 0xff, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  cogl_clip_pop ();
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0x00, 0x00, 0xff);


  /* - Create a 200x400 viewport and position it a (20, 10) inside the draw
   *   buffer.
   * - Push a 100x200 model space clip rectangle at (20, 10) in the viewport
   *   (i.e. (40, 20) inside the framebuffer)
   * - Fill the whole viewport with a green rectangle
   * - Verify that the framebuffer is black with a 100x200 green rectangle at
   *   (40, 20)
   */
  cogl_set_viewport (20, /* x */
                     10, /* y */
                     200, /* width */
                     400); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  /* figure out where to position our clip rectangle in model space
   * coordinates... */
  /* (offset 40 pixels right from the left of the viewport) */
  x0 = -1.0f + (2.0f / 200) * 20.f;
  /* (offset 20 pixels down from the top of the viewport) */
  y0 = 1.0f - (2.0f / 400) * 10.0f;
  width = (2.0f / 200) * 100;
  height = (2.0f / 400) * 200;
  /* add the clip rectangle... */
  cogl_push_matrix ();
  cogl_translate (x0 + (width/2.0), y0 - (height/2.0), 0);
  /* XXX: Rotate just enough to stop Cogl from converting our model space
   * rectangle into a window space rectangle.. */
  cogl_rotate (0.1, 0, 0, 1);
  cogl_clip_push_rectangle (-(width/2.0), -(height/2.0),
                            width/2.0, height/2.0);
  cogl_pop_matrix ();
  /* fill the viewport with green.. */
  cogl_set_source_color4ub (0x00, 0xff, 0x00, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  cogl_clip_pop ();
  assert_rectangle_color_and_black_border (40, 20, 100, 200,
                                           0x00, 0xff, 0x00);


  /* Set the viewport to something specific so we can verify that it gets
   * restored after we are done testing with an offscreen framebuffer... */
  cogl_set_viewport (20, 10, 100, 200);

  /*
   * Next test offscreen drawing...
   */
  data = g_malloc (FRAMEBUFFER_WIDTH * 4 * FRAMEBUFFER_HEIGHT);
  tex = cogl_texture_new_from_data (FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT,
                                    COGL_TEXTURE_NO_SLICING,
                                    COGL_PIXEL_FORMAT_RGBA_8888, /* data fmt */
                                    COGL_PIXEL_FORMAT_ANY, /* internal fmt */
                                    FRAMEBUFFER_WIDTH * 4, /* rowstride */
                                    data);
  g_free (data);
  offscreen = cogl_offscreen_new_to_texture (tex);

  cogl_push_framebuffer (offscreen);


  /* - Create a 100x200 viewport (i.e. smaller than the offscreen framebuffer)
   *   and position it a (20, 10) inside the framebuffer.
   * - Fill the whole viewport with a blue rectangle
   * - Verify that the framebuffer is black with a 100x200 blue rectangle at
   *   (20, 10)
   */
  cogl_set_viewport (20, /* x */
                     10, /* y */
                     100, /* width */
                     200); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  /* fill the viewport with blue.. */
  cogl_set_source_color4ub (0x00, 0x00, 0xff, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0x00, 0x00, 0xff);


  /* - Create a viewport twice the size of the offscreen framebuffer with
   *   a negative offset positioning it at (-20, -10) relative to the
   *   buffer itself.
   * - Draw a 100x200 red rectangle at (40, 20) within the viewport (which
   *   is (20, 10) within the framebuffer)
   * - Verify that the framebuffer is black with a 100x200 red rectangle at
   *   (20, 10)
   */
  cogl_set_viewport (-20, /* x */
                     -10, /* y */
                     FRAMEBUFFER_WIDTH * 2, /* width */
                     FRAMEBUFFER_HEIGHT * 2); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  /* draw a 100x200 red rectangle offset into the viewport such that its
   * top left corner should be found at (20, 10) in the offscreen buffer */
  /* (offset 40 pixels right from the left of the viewport) */
  x0 = -1.0f + (1.0f / FRAMEBUFFER_WIDTH) * 40.f;
  /* (offset 20 pixels down from the top of the viewport) */
  y0 = 1.0f - (1.0f / FRAMEBUFFER_HEIGHT) * 20.0f;
  width = (1.0f / FRAMEBUFFER_WIDTH) * 100;
  height = (1.0f / FRAMEBUFFER_HEIGHT) * 200;
  cogl_set_source_color4ub (0xff, 0x00, 0x00, 0xff);
  cogl_rectangle (x0, y0, x0 + width, y0 - height);
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0xff, 0x00, 0x00);


  /* - Create a 200x400 viewport and position it a (20, 10) inside the draw
   *   buffer.
   * - Push a 100x200 window space clip rectangle at (20, 10)
   * - Fill the whole viewport with a blue rectangle
   * - Verify that the framebuffer is black with a 100x200 blue rectangle at
   *   (20, 10)
   */
  cogl_set_viewport (20, /* x */
                     10, /* y */
                     200, /* width */
                     400); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  cogl_clip_push_window_rectangle (20, 10, 100, 200);
  /* fill the viewport with blue.. */
  cogl_set_source_color4ub (0x00, 0x00, 0xff, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  cogl_clip_pop ();
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0x00, 0x00, 0xff);


  /* - Create a 200x400 viewport and position it a (20, 10) inside the draw
   *   buffer.
   * - Push a 100x200 model space clip rectangle at (20, 10) in the viewport
   *   (i.e. (40, 20) inside the framebuffer)
   * - Fill the whole viewport with a green rectangle
   * - Verify that the framebuffer is black with a 100x200 green rectangle at
   *   (40, 20)
   */
  cogl_set_viewport (20, /* x */
                     10, /* y */
                     200, /* width */
                     400); /* height */
  /* clear everything... */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  /* figure out where to position our clip rectangle in model space
   * coordinates... */
  /* (offset 40 pixels right from the left of the viewport) */
  x0 = -1.0f + (2.0f / 200) * 20.f;
  /* (offset 20 pixels down from the top of the viewport) */
  y0 = 1.0f - (2.0f / 400) * 10.0f;
  width = (2.0f / 200) * 100;
  height = (2.0f / 400) * 200;
  /* add the clip rectangle... */
  cogl_push_matrix ();
  cogl_translate (x0 + (width/2.0), y0 - (height/2.0), 0);
  /* XXX: Rotate just enough to stop Cogl from converting our model space
   * rectangle into a window space rectangle.. */
  cogl_rotate (0.1, 0, 0, 1);
  cogl_clip_push_rectangle (-(width/2.0), -(height/2.0),
                            width/2, height/2);
  cogl_pop_matrix ();
  /* fill the viewport with green.. */
  cogl_set_source_color4ub (0x00, 0xff, 0x00, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  cogl_clip_pop ();
  assert_rectangle_color_and_black_border (40, 20, 100, 200,
                                           0x00, 0xff, 0x00);


  /* Set the viewport to something obscure to verify that it gets
   * replace when we switch back to the onscreen framebuffer... */
  cogl_set_viewport (0, 0, 10, 10);

  cogl_pop_framebuffer ();
  cogl_handle_unref (offscreen);

  /*
   * Verify that the previous onscreen framebuffer's viewport was restored
   * by drawing a white rectangle across the whole viewport. This should
   * draw a 100x200 rectangle at (20,10) relative to the onscreen draw
   * buffer...
   */
  cogl_clear (&black, COGL_BUFFER_BIT_COLOR);
  cogl_set_source_color4ub (0xff, 0xff, 0xff, 0xff);
  cogl_rectangle (-1, 1, 1, -1);
  assert_rectangle_color_and_black_border (20, 10, 100, 200,
                                           0xff, 0xff, 0xff);


  /* Uncomment to display the last contents of the offscreen framebuffer */
#if 1
  cogl_matrix_init_identity (&projection);
  cogl_matrix_init_identity (&modelview);
  cogl_set_viewport (0, 0, FRAMEBUFFER_WIDTH, FRAMEBUFFER_HEIGHT);
  cogl_set_projection_matrix (&projection);
  cogl_set_modelview_matrix (&modelview);
  cogl_set_source_texture (tex);
  cogl_rectangle (-1, 1, 1, -1);
#endif

  cogl_handle_unref (tex);

  /* Finally restore the stage's original state... */
  cogl_pop_matrix ();
  cogl_set_projection_matrix (&saved_projection);
  cogl_set_viewport (saved_viewport[0], saved_viewport[1],
                     saved_viewport[2], saved_viewport[3]);


  /* Comment this out if you want visual feedback of what this test
   * paints.
   */
  clutter_main_quit ();
}