mutter/clutter/clutter/clutter-deform-effect.c

/*
 * Clutter.
 *
 * An OpenGL based 'interactive canvas' library.
 *
 * Copyright (C) 2010  Intel Corporation.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library. If not, see <http://www.gnu.org/licenses/>.
 *
 * Author:
 *   Emmanuele Bassi <ebassi@linux.intel.com>
 *
 * Based on the MxDeformTexture class, written by:
 *   Chris Lord <chris@linux.intel.com>
 */

/**
 * ClutterDeformEffect:
 * 
 * A base class for effects deforming the geometry of an actor
 *
 * #ClutterDeformEffect is an abstract class providing all the plumbing
 * for creating effects that result in the deformation of an actor's
 * geometry.
 *
 * #ClutterDeformEffect uses offscreen buffers to render the contents of
 * a #ClutterActor and then the Cogl vertex buffers API to submit the
 * geometry to the GPU.
 *
 * ## Implementing ClutterDeformEffect
 *
 * Sub-classes of #ClutterDeformEffect should override the
 * #ClutterDeformEffectClass.deform_vertex() virtual function; this function
 * is called on every vertex that needs to be deformed by the effect.
 * Each passed vertex is an in-out parameter that initially contains the
 * position of the vertex and should be modified according to a specific
 * deformation algorithm.
 */

#include "clutter-build-config.h"

#include "clutter-deform-effect.h"

#include <cogl/cogl.h>

#include "clutter-color.h"
#include "clutter-debug.h"
#include "clutter-enum-types.h"
#include "clutter-offscreen-effect-private.h"
#include "clutter-paint-node.h"
#include "clutter-paint-nodes.h"
#include "clutter-private.h"

#define DEFAULT_N_TILES         32

struct _ClutterDeformEffectPrivate
{
  CoglPipeline *back_pipeline;

  gint x_tiles;
  gint y_tiles;

  CoglAttributeBuffer *buffer;

  CoglPrimitive *primitive;

  CoglPrimitive *lines_primitive;

  gint n_vertices;

  gulong allocation_id;

  guint is_dirty : 1;
};

enum
{
  PROP_0,

  PROP_X_TILES,
  PROP_Y_TILES,

  PROP_BACK_MATERIAL,

  PROP_LAST
};

static GParamSpec *obj_props[PROP_LAST];

G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (ClutterDeformEffect,
                                     clutter_deform_effect,
                                     CLUTTER_TYPE_OFFSCREEN_EFFECT)

static void
clutter_deform_effect_real_deform_vertex (ClutterDeformEffect *effect,
                                          gfloat               width,
                                          gfloat               height,
                                          CoglTextureVertex   *vertex)
{
  g_warning ("%s: Deformation effect of type '%s' does not implement "
             "the required ClutterDeformEffect::deform_vertex virtual "
             "function.",
             G_STRLOC,
             G_OBJECT_TYPE_NAME (effect));
}

static void
clutter_deform_effect_deform_vertex (ClutterDeformEffect *effect,
                                     gfloat               width,
                                     gfloat               height,
                                     CoglTextureVertex   *vertex)
{
  CLUTTER_DEFORM_EFFECT_GET_CLASS (effect)->deform_vertex (effect,
                                                           width, height,
                                                           vertex);
}

static void
vbo_invalidate (ClutterActor        *actor,
                GParamSpec          *pspec,
                ClutterDeformEffect *effect)
{
  effect->priv->is_dirty = TRUE;
}

static void
clutter_deform_effect_set_actor (ClutterActorMeta *meta,
                                 ClutterActor     *actor)
{
  ClutterDeformEffectPrivate *priv = CLUTTER_DEFORM_EFFECT (meta)->priv;

  if (priv->allocation_id != 0)
    {
      ClutterActor *old_actor = clutter_actor_meta_get_actor (meta);

      if (old_actor != NULL)
        g_clear_signal_handler (&priv->allocation_id, old_actor);

      priv->allocation_id = 0;
    }

  /* we need to invalidate the VBO whenever the allocation of the actor
   * changes
   */
  if (actor != NULL)
    priv->allocation_id = g_signal_connect (actor, "notify::allocation",
                                            G_CALLBACK (vbo_invalidate),
                                            meta);

  priv->is_dirty = TRUE;

  CLUTTER_ACTOR_META_CLASS (clutter_deform_effect_parent_class)->set_actor (meta, actor);
}

static void
clutter_deform_effect_paint_target (ClutterOffscreenEffect *effect,
                                    ClutterPaintNode       *node,
                                    ClutterPaintContext    *paint_context)
{
  ClutterDeformEffect *self= CLUTTER_DEFORM_EFFECT (effect);
  ClutterDeformEffectPrivate *priv = self->priv;
  CoglPipeline *pipeline;
  CoglDepthState depth_state;

  if (priv->is_dirty)
    {
      gboolean mapped_buffer;
      CoglVertexP3T2C4 *verts;
      ClutterActor *actor;
      gfloat width, height;
      guint opacity;
      gint i, j;

      actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
      opacity = clutter_actor_get_paint_opacity (actor);

      /* if we don't have a target size, fall back to the actor's
       * allocation, though wrong it might be
       */
      if (!clutter_offscreen_effect_get_target_size (effect, &width, &height))
        clutter_actor_get_size (actor, &width, &height);

      /* XXX ideally, the sub-classes should tell us what they
       * changed in the texture vertices; we then would be able to
       * avoid resubmitting the same data, if it did not change. for
       * the time being, we resubmit everything
       */
      verts = cogl_buffer_map (COGL_BUFFER (priv->buffer),
                               COGL_BUFFER_ACCESS_WRITE,
                               COGL_BUFFER_MAP_HINT_DISCARD);

      /* If the map failed then we'll resort to allocating a temporary
         buffer */
      if (verts == NULL)
        {
          mapped_buffer = FALSE;
          verts = g_malloc (sizeof (*verts) * priv->n_vertices);
        }
      else
        mapped_buffer = TRUE;

      for (i = 0; i < priv->y_tiles + 1; i++)
        {
          for (j = 0; j < priv->x_tiles + 1; j++)
            {
              CoglVertexP3T2C4 *vertex_out;
              CoglTextureVertex vertex;

              /* CoglTextureVertex isn't an ideal structure to use for
                 this because it contains a CoglColor. The internal
                 layout of CoglColor is mean to be private so Clutter
                 can not pass a pointer to it as a vertex
                 attribute. Also it contains padding so we end up
                 storing more data in the vertex buffer than we need
                 to. Instead we let the application modify a dummy
                 vertex and then copy the details back out to a more
                 well-defined struct */

              vertex.tx = (float) j / priv->x_tiles;
              vertex.ty = (float) i / priv->y_tiles;

              vertex.x = width * vertex.tx;
              vertex.y = height * vertex.ty;
              vertex.z = 0.0f;

              cogl_color_init_from_4ub (&vertex.color, 255, 255, 255, opacity);

              clutter_deform_effect_deform_vertex (self,
                                                   width, height,
                                                   &vertex);

              vertex_out = verts + i * (priv->x_tiles + 1) + j;

              vertex_out->x = vertex.x;
              vertex_out->y = vertex.y;
              vertex_out->z = vertex.z;
              vertex_out->s = vertex.tx;
              vertex_out->t = vertex.ty;
              vertex_out->r = cogl_color_get_red_byte (&vertex.color);
              vertex_out->g = cogl_color_get_green_byte (&vertex.color);
              vertex_out->b = cogl_color_get_blue_byte (&vertex.color);
              vertex_out->a = cogl_color_get_alpha_byte (&vertex.color);
            }
        }

      if (mapped_buffer)
        cogl_buffer_unmap (COGL_BUFFER (priv->buffer));
      else
        {
          cogl_buffer_set_data (COGL_BUFFER (priv->buffer),
                                0, /* offset */
                                verts,
                                sizeof (*verts) * priv->n_vertices);
          g_free (verts);
        }

      priv->is_dirty = FALSE;
    }

  pipeline = clutter_offscreen_effect_get_pipeline (effect);

  /* enable depth testing */
  cogl_depth_state_init (&depth_state);
  cogl_depth_state_set_test_enabled (&depth_state, TRUE);
  cogl_depth_state_set_test_function (&depth_state, COGL_DEPTH_TEST_FUNCTION_LEQUAL);
  cogl_pipeline_set_depth_state (pipeline, &depth_state, NULL);

  /* enable backface culling if we have a back material */
  if (priv->back_pipeline != NULL)
    cogl_pipeline_set_cull_face_mode (pipeline,
                                      COGL_PIPELINE_CULL_FACE_MODE_BACK);

  /* draw the front */
  if (pipeline != NULL)
    {
      ClutterPaintNode *front_node;

      front_node = clutter_pipeline_node_new (pipeline);
      clutter_paint_node_set_static_name (front_node,
                                          "ClutterDeformEffect (front)");
      clutter_paint_node_add_child (node, front_node);
      clutter_paint_node_add_primitive (front_node, priv->primitive);
      clutter_paint_node_unref (front_node);
    }

  /* draw the back */
  if (priv->back_pipeline != NULL)
    {
      ClutterPaintNode *back_node;
      CoglPipeline *back_pipeline;

      /* We probably shouldn't be modifying the user's material so
         instead we make a temporary copy */
      back_pipeline = cogl_pipeline_copy (priv->back_pipeline);
      cogl_pipeline_set_depth_state (back_pipeline, &depth_state, NULL);
      cogl_pipeline_set_cull_face_mode (back_pipeline,
                                        COGL_PIPELINE_CULL_FACE_MODE_FRONT);


      back_node = clutter_pipeline_node_new (back_pipeline);
      clutter_paint_node_set_static_name (back_node,
                                          "ClutterDeformEffect (back)");
      clutter_paint_node_add_child (node, back_node);
      clutter_paint_node_add_primitive (back_node, priv->primitive);

      clutter_paint_node_unref (back_node);
      cogl_object_unref (back_pipeline);
    }

  if (G_UNLIKELY (priv->lines_primitive != NULL))
    {
      const ClutterColor *red;
      ClutterPaintNode *lines_node;

      red = clutter_color_get_static (CLUTTER_COLOR_RED);

      lines_node = clutter_color_node_new (red);
      clutter_paint_node_set_static_name (lines_node,
                                          "ClutterDeformEffect (lines)");
      clutter_paint_node_add_child (node, lines_node);
      clutter_paint_node_add_primitive (lines_node, priv->lines_primitive);
      clutter_paint_node_unref (lines_node);
    }
}

static inline void
clutter_deform_effect_free_arrays (ClutterDeformEffect *self)
{
  ClutterDeformEffectPrivate *priv = self->priv;

  if (priv->buffer)
    {
      cogl_object_unref (priv->buffer);
      priv->buffer = NULL;
    }

  if (priv->primitive)
    {
      cogl_object_unref (priv->primitive);
      priv->primitive = NULL;
    }

  if (priv->lines_primitive)
    {
      cogl_object_unref (priv->lines_primitive);
      priv->lines_primitive = NULL;
    }
}

static void
clutter_deform_effect_init_arrays (ClutterDeformEffect *self)
{
  ClutterDeformEffectPrivate *priv = self->priv;
  gint x, y, direction, n_indices;
  CoglAttribute *attributes[3];
  guint16 *static_indices;
  CoglContext *ctx =
    clutter_backend_get_cogl_context (clutter_get_default_backend ());
  CoglIndices *indices;
  guint16 *idx;
  int i;

  clutter_deform_effect_free_arrays (self);

  n_indices = ((2 + 2 * priv->x_tiles)
               * priv->y_tiles
               + (priv->y_tiles - 1));

  static_indices = g_new (guint16, n_indices);

#define MESH_INDEX(x,y) ((y) * (priv->x_tiles + 1) + (x))

  /* compute all the triangles from the various tiles */
  direction = 1;

  idx = static_indices;
  idx[0] = MESH_INDEX (0, 0);
  idx[1] = MESH_INDEX (0, 1);
  idx += 2;

  for (y = 0; y < priv->y_tiles; y++)
    {
      for (x = 0; x < priv->x_tiles; x++)
        {
          if (direction)
            {
              idx[0] = MESH_INDEX (x + 1, y);
              idx[1] = MESH_INDEX (x + 1, y + 1);
            }
          else
            {
              idx[0] = MESH_INDEX (priv->x_tiles - x - 1, y);
              idx[1] = MESH_INDEX (priv->x_tiles - x - 1, y + 1);
            }

          idx += 2;
        }

      if (y == (priv->y_tiles - 1))
        break;

      if (direction)
        {
          idx[0] = MESH_INDEX (priv->x_tiles, y + 1);
          idx[1] = MESH_INDEX (priv->x_tiles, y + 1);
          idx[2] = MESH_INDEX (priv->x_tiles, y + 2);
        }
      else
        {
          idx[0] = MESH_INDEX (0, y + 1);
          idx[1] = MESH_INDEX (0, y + 1);
          idx[2] = MESH_INDEX (0, y + 2);
        }

      idx += 3;

      direction = !direction;
    }

#undef MESH_INDEX

  indices = cogl_indices_new (ctx,
                              COGL_INDICES_TYPE_UNSIGNED_SHORT,
                              static_indices,
                              n_indices);

  g_free (static_indices);

  priv->n_vertices = (priv->x_tiles + 1) * (priv->y_tiles + 1);

  priv->buffer =
    cogl_attribute_buffer_new (ctx,
                               sizeof (CoglVertexP3T2C4) *
                               priv->n_vertices,
                               NULL);

  /* The application is expected to continuously modify the vertices
     so we should give a hint to Cogl about that */
  cogl_buffer_set_update_hint (COGL_BUFFER (priv->buffer),
                               COGL_BUFFER_UPDATE_HINT_DYNAMIC);

  attributes[0] = cogl_attribute_new (priv->buffer,
                                      "cogl_position_in",
                                      sizeof (CoglVertexP3T2C4),
                                      G_STRUCT_OFFSET (CoglVertexP3T2C4, x),
                                      3, /* n_components */
                                      COGL_ATTRIBUTE_TYPE_FLOAT);
  attributes[1] = cogl_attribute_new (priv->buffer,
                                      "cogl_tex_coord0_in",
                                      sizeof (CoglVertexP3T2C4),
                                      G_STRUCT_OFFSET (CoglVertexP3T2C4, s),
                                      2, /* n_components */
                                      COGL_ATTRIBUTE_TYPE_FLOAT);
  attributes[2] = cogl_attribute_new (priv->buffer,
                                      "cogl_color_in",
                                      sizeof (CoglVertexP3T2C4),
                                      G_STRUCT_OFFSET (CoglVertexP3T2C4, r),
                                      4, /* n_components */
                                      COGL_ATTRIBUTE_TYPE_UNSIGNED_BYTE);

  priv->primitive =
    cogl_primitive_new_with_attributes (COGL_VERTICES_MODE_TRIANGLE_STRIP,
                                        priv->n_vertices,
                                        attributes,
                                        3 /* n_attributes */);
  cogl_primitive_set_indices (priv->primitive,
                              indices,
                              n_indices);

  if (G_UNLIKELY (clutter_paint_debug_flags & CLUTTER_DEBUG_PAINT_DEFORM_TILES))
    {
      priv->lines_primitive =
        cogl_primitive_new_with_attributes (COGL_VERTICES_MODE_LINE_STRIP,
                                            priv->n_vertices,
                                            attributes,
                                            2 /* n_attributes */);
      cogl_primitive_set_indices (priv->lines_primitive,
                                  indices,
                                  n_indices);
    }

  cogl_object_unref (indices);

  for (i = 0; i < 3; i++)
    cogl_object_unref (attributes[i]);

  priv->is_dirty = TRUE;
}

static inline void
clutter_deform_effect_free_back_pipeline (ClutterDeformEffect *self)
{
  ClutterDeformEffectPrivate *priv = self->priv;

  if (priv->back_pipeline != NULL)
    {
      cogl_object_unref (priv->back_pipeline);
      priv->back_pipeline = NULL;
    }
}

static void
clutter_deform_effect_finalize (GObject *gobject)
{
  ClutterDeformEffect *self = CLUTTER_DEFORM_EFFECT (gobject);

  clutter_deform_effect_free_arrays (self);
  clutter_deform_effect_free_back_pipeline (self);

  G_OBJECT_CLASS (clutter_deform_effect_parent_class)->finalize (gobject);
}

static void
clutter_deform_effect_set_property (GObject      *gobject,
                                    guint         prop_id,
                                    const GValue *value,
                                    GParamSpec   *pspec)
{
  ClutterDeformEffect *self = CLUTTER_DEFORM_EFFECT (gobject);

  switch (prop_id)
    {
    case PROP_X_TILES:
      clutter_deform_effect_set_n_tiles (self, g_value_get_uint (value),
                                         self->priv->y_tiles);
      break;

    case PROP_Y_TILES:
      clutter_deform_effect_set_n_tiles (self, self->priv->x_tiles,
                                         g_value_get_uint (value));
      break;

    case PROP_BACK_MATERIAL:
      clutter_deform_effect_set_back_material (self, g_value_get_boxed (value));
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
clutter_deform_effect_get_property (GObject    *gobject,
                                    guint       prop_id,
                                    GValue     *value,
                                    GParamSpec *pspec)
{
  ClutterDeformEffectPrivate *priv = CLUTTER_DEFORM_EFFECT (gobject)->priv;

  switch (prop_id)
    {
    case PROP_X_TILES:
      g_value_set_uint (value, priv->x_tiles);
      break;

    case PROP_Y_TILES:
      g_value_set_uint (value, priv->y_tiles);
      break;

    case PROP_BACK_MATERIAL:
      g_value_set_boxed (value, priv->back_pipeline);
      break;

    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID (gobject, prop_id, pspec);
      break;
    }
}

static void
clutter_deform_effect_class_init (ClutterDeformEffectClass *klass)
{
  GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
  ClutterActorMetaClass *meta_class = CLUTTER_ACTOR_META_CLASS (klass);
  ClutterOffscreenEffectClass *offscreen_class = CLUTTER_OFFSCREEN_EFFECT_CLASS (klass);

  klass->deform_vertex = clutter_deform_effect_real_deform_vertex;

  /**
   * ClutterDeformEffect:x-tiles:
   *
   * The number of horizontal tiles. The bigger the number, the
   * smaller the tiles
   */
  obj_props[PROP_X_TILES] =
    g_param_spec_uint ("x-tiles",
                       P_("Horizontal Tiles"),
                       P_("The number of horizontal tiles"),
                       1, G_MAXUINT,
                       DEFAULT_N_TILES,
                       CLUTTER_PARAM_READWRITE);

  /**
   * ClutterDeformEffect:y-tiles:
   *
   * The number of vertical tiles. The bigger the number, the
   * smaller the tiles
   */
  obj_props[PROP_Y_TILES] =
    g_param_spec_uint ("y-tiles",
                       P_("Vertical Tiles"),
                       P_("The number of vertical tiles"),
                       1, G_MAXUINT,
                       DEFAULT_N_TILES,
                       CLUTTER_PARAM_READWRITE);

  /**
   * ClutterDeformEffect:back-material:
   *
   * A material to be used when painting the back of the actor
   * to which this effect has been applied
   *
   * By default, no material will be used
   */
  obj_props[PROP_BACK_MATERIAL] =
    g_param_spec_boxed ("back-material",
                        P_("Back Material"),
                        P_("The material to be used when painting the back of the actor"),
                        COGL_TYPE_HANDLE,
                        CLUTTER_PARAM_READWRITE);

  gobject_class->finalize = clutter_deform_effect_finalize;
  gobject_class->set_property = clutter_deform_effect_set_property;
  gobject_class->get_property = clutter_deform_effect_get_property;
  g_object_class_install_properties (gobject_class,
                                     PROP_LAST,
                                     obj_props);

  meta_class->set_actor = clutter_deform_effect_set_actor;

  offscreen_class->paint_target = clutter_deform_effect_paint_target;
}

static void
clutter_deform_effect_init (ClutterDeformEffect *self)
{
  self->priv = clutter_deform_effect_get_instance_private (self);
  self->priv->x_tiles = self->priv->y_tiles = DEFAULT_N_TILES;
  self->priv->back_pipeline = NULL;

  clutter_deform_effect_init_arrays (self);
}

/**
 * clutter_deform_effect_set_back_material:
 * @effect: a #ClutterDeformEffect
 * @material: (allow-none): a handle to a Cogl material
 *
 * Sets the material that should be used when drawing the back face
 * of the actor during a deformation
 *
 * The #ClutterDeformEffect will take a reference on the material's
 * handle
 */
void
clutter_deform_effect_set_back_material (ClutterDeformEffect *effect,
                                         CoglHandle           material)
{
  ClutterDeformEffectPrivate *priv;
  CoglPipeline *pipeline = COGL_PIPELINE (material);

  g_return_if_fail (CLUTTER_IS_DEFORM_EFFECT (effect));
  g_return_if_fail (pipeline == NULL || cogl_is_pipeline (pipeline));

  priv = effect->priv;

  clutter_deform_effect_free_back_pipeline (effect);

  priv->back_pipeline = material;
  if (priv->back_pipeline != NULL)
    cogl_object_ref (priv->back_pipeline);

  clutter_deform_effect_invalidate (effect);
}

/**
 * clutter_deform_effect_get_back_material:
 * @effect: a #ClutterDeformEffect
 *
 * Retrieves the handle to the back face material used by @effect
 *
 * Return value: (transfer none): a handle for the material, or %NULL.
 *   The returned material is owned by the #ClutterDeformEffect and it
 *   should not be freed directly
 */
CoglHandle
clutter_deform_effect_get_back_material (ClutterDeformEffect *effect)
{
  g_return_val_if_fail (CLUTTER_IS_DEFORM_EFFECT (effect), NULL);

  return effect->priv->back_pipeline;
}

/**
 * clutter_deform_effect_set_n_tiles:
 * @effect: a #ClutterDeformEffect
 * @x_tiles: number of horizontal tiles
 * @y_tiles: number of vertical tiles
 *
 * Sets the number of horizontal and vertical tiles to be used
 * when applying the effect
 *
 * More tiles allow a finer grained deformation at the expenses
 * of computation
 */
void
clutter_deform_effect_set_n_tiles (ClutterDeformEffect *effect,
                                   guint                x_tiles,
                                   guint                y_tiles)
{
  ClutterDeformEffectPrivate *priv;
  gboolean tiles_changed = FALSE;

  g_return_if_fail (CLUTTER_IS_DEFORM_EFFECT (effect));
  g_return_if_fail (x_tiles > 0 && y_tiles > 0);

  priv = effect->priv;

  g_object_freeze_notify (G_OBJECT (effect));

  if (priv->x_tiles != x_tiles)
    {
      priv->x_tiles = x_tiles;

      g_object_notify_by_pspec (G_OBJECT (effect), obj_props[PROP_X_TILES]);

      tiles_changed = TRUE;
    }

  if (priv->y_tiles != y_tiles)
    {
      priv->y_tiles = y_tiles;

      g_object_notify_by_pspec (G_OBJECT (effect), obj_props[PROP_Y_TILES]);

      tiles_changed = TRUE;
    }

  if (tiles_changed)
    {
      clutter_deform_effect_init_arrays (effect);
      clutter_deform_effect_invalidate (effect);
    }

  g_object_thaw_notify (G_OBJECT (effect));
}

/**
 * clutter_deform_effect_get_n_tiles:
 * @effect: a #ClutterDeformEffect
 * @x_tiles: (out): return location for the number of horizontal tiles,
 *   or %NULL
 * @y_tiles: (out): return location for the number of vertical tiles,
 *   or %NULL
 *
 * Retrieves the number of horizontal and vertical tiles used to sub-divide
 * the actor's geometry during the effect
 */
void
clutter_deform_effect_get_n_tiles (ClutterDeformEffect *effect,
                                   guint               *x_tiles,
                                   guint               *y_tiles)
{
  g_return_if_fail (CLUTTER_IS_DEFORM_EFFECT (effect));

  if (x_tiles != NULL)
    *x_tiles = effect->priv->x_tiles;

  if (y_tiles != NULL)
    *y_tiles = effect->priv->y_tiles;
}

/**
 * clutter_deform_effect_invalidate:
 * @effect: a #ClutterDeformEffect
 *
 * Invalidates the `effect`'s vertices and, if it is associated
 * to an actor, it will queue a redraw
 */
void
clutter_deform_effect_invalidate (ClutterDeformEffect *effect)
{
  ClutterActor *actor;

  g_return_if_fail (CLUTTER_IS_DEFORM_EFFECT (effect));

  if (effect->priv->is_dirty)
    return;

  effect->priv->is_dirty = TRUE;

  actor = clutter_actor_meta_get_actor (CLUTTER_ACTOR_META (effect));
  if (actor != NULL)
    clutter_effect_queue_repaint (CLUTTER_EFFECT (effect));
}