/*
* 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/>.
*
* Authors:
* Emmanuele Bassi <ebassi@linux.intel.com>
* Robert Bragg <robert@linux.intel.com>
*/
/**
* SECTION:clutter-offscreen-effect
* @short_description: Base class for effects using offscreen buffers
* @see_also: #ClutterBlurEffect, #ClutterEffect
*
* #ClutterOffscreenEffect is an abstract class that can be used by
* #ClutterEffect sub-classes requiring access to an offscreen buffer.
*
* Some effects, like the fragment shader based effects, can only use GL
* textures, and in order to apply those effects to any kind of actor they
* require that all drawing operations are applied to an offscreen framebuffer
* that gets redirected to a texture.
*
* #ClutterOffscreenEffect provides all the heavy-lifting for creating the
* offscreen framebuffer, the redirection and the final paint of the texture on
* the desired stage.
*
* <refsect2 id="ClutterOffscreenEffect-implementing">
* <title>Implementing a ClutterOffscreenEffect</title>
* <para>Creating a sub-class of #ClutterOffscreenEffect requires, in case
* of overriding the #ClutterEffect virtual functions, to chain up to the
* #ClutterOffscreenEffect's implementation.</para>
* <para>On top of the #ClutterEffect's virtual functions,
* #ClutterOffscreenEffect also provides a <function>paint_target()</function>
* function, which encapsulates the effective painting of the texture that
* contains the result of the offscreen redirection.</para>
* <para>The size of the target material is defined to be as big as the
* transformed size of the #ClutterActor using the offscreen effect.
* Sub-classes of #ClutterOffscreenEffect can change the texture creation
* code to provide bigger textures by overriding the
* <function>create_texture()</function> virtual function; no chain up
* to the #ClutterOffscreenEffect implementation is required in this
* case.</para>
* </refsect2>
*
* #ClutterOffscreenEffect is available since Clutter 1.4
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "clutter-offscreen-effect.h"
#include "cogl/cogl.h"
#include "clutter-debug.h"
#include "clutter-private.h"
struct _ClutterOffscreenEffectPrivate
{
CoglHandle offscreen;
CoglMaterial *target;
ClutterActor *actor;
ClutterActor *stage;
gfloat x_offset;
gfloat y_offset;
gfloat target_width;
gfloat target_height;
};
G_DEFINE_ABSTRACT_TYPE (ClutterOffscreenEffect,
clutter_offscreen_effect,
CLUTTER_TYPE_EFFECT);
static void
clutter_offscreen_effect_set_actor (ClutterActorMeta *meta,
ClutterActor *actor)
{
ClutterOffscreenEffect *self = CLUTTER_OFFSCREEN_EFFECT (meta);
ClutterOffscreenEffectPrivate *priv = self->priv;
ClutterActorMetaClass *meta_class;
meta_class = CLUTTER_ACTOR_META_CLASS (clutter_offscreen_effect_parent_class);
meta_class->set_actor (meta, actor);
/* clear out the previous state */
if (priv->offscreen != COGL_INVALID_HANDLE)
{
cogl_handle_unref (priv->offscreen);
priv->offscreen = COGL_INVALID_HANDLE;
}
if (priv->target != COGL_INVALID_HANDLE)
{
cogl_handle_unref (priv->target);
priv->target = COGL_INVALID_HANDLE;
}
/* we keep a back pointer here, to avoid going through the ActorMeta */
priv->actor = clutter_actor_meta_get_actor (meta);
}
static CoglHandle
clutter_offscreen_effect_real_create_texture (ClutterOffscreenEffect *effect,
gfloat width,
gfloat height)
{
return cogl_texture_new_with_size (MAX (width, 1), MAX (height, 1),
COGL_TEXTURE_NO_SLICING,
COGL_PIXEL_FORMAT_RGBA_8888_PRE);
}
static gboolean
update_fbo (ClutterEffect *effect)
{
ClutterOffscreenEffect *self = CLUTTER_OFFSCREEN_EFFECT (effect);
ClutterOffscreenEffectPrivate *priv = self->priv;
gfloat width, height;
CoglHandle texture;
priv->stage = clutter_actor_get_stage (priv->actor);
if (priv->stage == NULL)
{
CLUTTER_NOTE (MISC, "The actor '%s' is not part of a stage",
clutter_actor_get_name (priv->actor) == NULL
? G_OBJECT_TYPE_NAME (priv->actor)
: clutter_actor_get_name (priv->actor));
return FALSE;
}
/* the target should at least be big enough to contain the
* transformed allocation of the actor
*
* FIXME - this is actually not enough: we need the paint area
* to make this work reliably
*/
clutter_actor_get_transformed_size (priv->actor, &width, &height);
if (priv->target_width == width &&
priv->target_height == height)
return TRUE;
if (priv->target != COGL_INVALID_HANDLE)
{
cogl_handle_unref (priv->target);
cogl_handle_unref (priv->offscreen);
}
priv->target = cogl_material_new ();
texture = clutter_offscreen_effect_create_texture (self, width, height);
if (texture == COGL_INVALID_HANDLE)
return FALSE;
cogl_material_set_layer (priv->target, 0, texture);
cogl_handle_unref (texture);
/* we need to use the size of the texture target and not the minimum
* size we passed to the create_texture() vfunc, as any sub-class might
* give use a bigger texture
*/
priv->target_width = cogl_texture_get_width (texture);
priv->target_height = cogl_texture_get_height (texture);
priv->offscreen = cogl_offscreen_new_to_texture (texture);
if (priv->offscreen == COGL_INVALID_HANDLE)
{
g_warning ("%s: Unable to create an Offscreen buffer", G_STRLOC);
cogl_handle_unref (priv->target);
priv->target = COGL_INVALID_HANDLE;
priv->target_width = 0;
priv->target_height = 0;
return FALSE;
}
return TRUE;
}
static void
get_screen_offsets (ClutterActor *actor,
gfloat *x_offset,
gfloat *y_offset)
{
ClutterVertex verts[4];
gfloat x_min = G_MAXFLOAT, y_min = G_MAXFLOAT;
gfloat v[4] = { 0, };
gint i;
/* Get the actors allocation transformed into screen coordinates.
*
* XXX: Note: this may not be a bounding box for the actor, since an
* actor with depth may escape the box due to its perspective
* projection. */
clutter_actor_get_abs_allocation_vertices (actor, verts);
for (i = 0; i < G_N_ELEMENTS (verts); ++i)
{
if (verts[i].x < x_min)
x_min = verts[i].x;
if (verts[i].y < y_min)
y_min = verts[i].y;
}
/* XXX: It's not good enough to round by simply truncating the fraction here
* via a cast, as it results in offscreen rendering being offset by 1 pixel
* in many cases... */
#define ROUND(x) ((x) >= 0 ? (long)((x) + 0.5) : (long)((x) - 0.5))
*x_offset = ROUND (x_min);
*y_offset = ROUND (y_min);
#undef ROUND
/* since we're setting up a viewport with a negative offset to paint
* in an FBO with the same modelview and projection matrices as the
* stage, we need to offset the computed absolute allocation vertices
* with the current viewport's X and Y offsets. this works even with
* the default case where the viewport is set up by Clutter to be
* (0, 0, stage_width, stage_height)
*/
cogl_get_viewport (v);
*x_offset -= v[0];
*y_offset -= v[1];
}
static gboolean
clutter_offscreen_effect_pre_paint (ClutterEffect *effect)
{
ClutterOffscreenEffect *self = CLUTTER_OFFSCREEN_EFFECT (effect);
ClutterOffscreenEffectPrivate *priv = self->priv;
CoglMatrix projection;
CoglColor transparent;
CoglMatrix modelview;
gfloat width, height;
if (!clutter_actor_meta_get_enabled (CLUTTER_ACTOR_META (effect)))
return FALSE;
if (priv->actor == NULL)
return FALSE;
if (!update_fbo (effect))
return FALSE;
/* get the current modelview matrix so that we can copy it
* to the framebuffer
*/
cogl_get_modelview_matrix (&modelview);
/* let's draw offscreen */
cogl_push_framebuffer (priv->offscreen);
/* set up the viewport so that it has the same size of the stage,
* and it has its origin at the same position of the stage's; also
* set up the perspective to be the same as the stage's
*/
clutter_actor_get_size (priv->stage, &width, &height);
get_screen_offsets (priv->actor, &priv->x_offset, &priv->y_offset);
cogl_set_viewport (-priv->x_offset, -priv->y_offset, width, height);
/* Copy the stage's projection matrix across to the framebuffer */
_clutter_stage_get_projection_matrix (CLUTTER_STAGE (priv->stage),
&projection);
cogl_set_projection_matrix (&projection);
/* Copy the modelview that would have been used if rendering onscreen */
cogl_set_modelview_matrix (&modelview);
cogl_color_init_from_4ub (&transparent, 0, 0, 0, 0);
cogl_clear (&transparent,
COGL_BUFFER_BIT_COLOR |
COGL_BUFFER_BIT_DEPTH);
cogl_push_matrix ();
return TRUE;
}
static void
clutter_offscreen_effect_real_paint_target (ClutterOffscreenEffect *effect)
{
ClutterOffscreenEffectPrivate *priv = effect->priv;
guint8 paint_opacity;
paint_opacity = clutter_actor_get_paint_opacity (priv->actor);
cogl_material_set_color4ub (priv->target,
paint_opacity,
paint_opacity,
paint_opacity,
paint_opacity);
cogl_set_source (priv->target);
/* paint the texture at the same position as the actor would be,
* in Stage coordinates, since we set up the modelview matrix to
* be exactly as the stage sets it up, plus the eventual offsets
* due to offscreen effects stacking
*/
cogl_rectangle_with_texture_coords (0, 0,
priv->target_width,
priv->target_height,
0.0, 0.0,
1.0, 1.0);
}
static void
clutter_offscreen_effect_post_paint (ClutterEffect *effect)
{
ClutterOffscreenEffect *self = CLUTTER_OFFSCREEN_EFFECT (effect);
ClutterOffscreenEffectPrivate *priv = self->priv;
CoglMatrix modelview;
if (priv->offscreen == COGL_INVALID_HANDLE ||
priv->target == COGL_INVALID_HANDLE ||
priv->actor == NULL)
return;
cogl_pop_matrix ();
cogl_pop_framebuffer ();
cogl_push_matrix ();
/* Now reset the modelview to put us in stage coordinates so
* we can drawn the result of our offscreen render as a textured
* quad... */
cogl_matrix_init_identity (&modelview);
_clutter_actor_apply_modelview_transform (priv->stage, &modelview);
cogl_matrix_translate (&modelview, priv->x_offset, priv->y_offset, 0.0f);
cogl_set_modelview_matrix (&modelview);
/* paint the target material; this is virtualized for
* sub-classes that require special hand-holding
*/
clutter_offscreen_effect_paint_target (self);
cogl_pop_matrix ();
}
static void
clutter_offscreen_effect_finalize (GObject *gobject)
{
ClutterOffscreenEffect *self = CLUTTER_OFFSCREEN_EFFECT (gobject);
ClutterOffscreenEffectPrivate *priv = self->priv;
if (priv->offscreen)
cogl_handle_unref (priv->offscreen);
if (priv->target)
cogl_handle_unref (priv->target);
G_OBJECT_CLASS (clutter_offscreen_effect_parent_class)->finalize (gobject);
}
static void
clutter_offscreen_effect_class_init (ClutterOffscreenEffectClass *klass)
{
ClutterActorMetaClass *meta_class = CLUTTER_ACTOR_META_CLASS (klass);
ClutterEffectClass *effect_class = CLUTTER_EFFECT_CLASS (klass);
GObjectClass *gobject_class = G_OBJECT_CLASS (klass);
g_type_class_add_private (klass, sizeof (ClutterOffscreenEffectPrivate));
klass->create_texture = clutter_offscreen_effect_real_create_texture;
klass->paint_target = clutter_offscreen_effect_real_paint_target;
meta_class->set_actor = clutter_offscreen_effect_set_actor;
effect_class->pre_paint = clutter_offscreen_effect_pre_paint;
effect_class->post_paint = clutter_offscreen_effect_post_paint;
gobject_class->finalize = clutter_offscreen_effect_finalize;
}
static void
clutter_offscreen_effect_init (ClutterOffscreenEffect *self)
{
self->priv = G_TYPE_INSTANCE_GET_PRIVATE (self,
CLUTTER_TYPE_OFFSCREEN_EFFECT,
ClutterOffscreenEffectPrivate);
}
/**
* clutter_offscreen_effect_get_target:
* @effect: a #ClutterOffscreenEffect
*
* Retrieves the material used as a render target for the offscreen
* buffer created by @effect
*
* You should only use the returned #CoglMaterial when painting. The
* returned material might change between different frames.
*
* Return value: (transfer none): a #CoglMaterial or %NULL. The
* returned material is owned by Clutter and it should not be
* modified or freed
*
* Since: 1.4
*/
CoglMaterial *
clutter_offscreen_effect_get_target (ClutterOffscreenEffect *effect)
{
g_return_val_if_fail (CLUTTER_IS_OFFSCREEN_EFFECT (effect),
COGL_INVALID_HANDLE);
return effect->priv->target;
}
/**
* clutter_offscreen_effect_paint_target:
* @effect: a #ClutterOffscreenEffect
*
* Calls the paint_target() virtual function of the @effect
*
* Since: 1.4
*/
void
clutter_offscreen_effect_paint_target (ClutterOffscreenEffect *effect)
{
g_return_if_fail (CLUTTER_IS_OFFSCREEN_EFFECT (effect));
CLUTTER_OFFSCREEN_EFFECT_GET_CLASS (effect)->paint_target (effect);
}
/**
* clutter_offscreen_effect_create_texture:
* @effect: a #ClutterOffscreenEffect
* @width: the minimum width of the target texture
* @height: the minimum height of the target texture
*
* Calls the create_texture() virtual function of the @effect
*
* Return value: (transfer full): a handle to a Cogl texture, or
* %COGL_INVALID_HANDLE. The returned handle has its reference
* count increased.
*
* Since: 1.4
*/
CoglHandle
clutter_offscreen_effect_create_texture (ClutterOffscreenEffect *effect,
gfloat width,
gfloat height)
{
g_return_val_if_fail (CLUTTER_IS_OFFSCREEN_EFFECT (effect),
COGL_INVALID_HANDLE);
return CLUTTER_OFFSCREEN_EFFECT_GET_CLASS (effect)->create_texture (effect,
width,
height);
}