Class
ClutterOffscreenEffect
Description [src]
abstract class Clutter.OffscreenEffect : Clutter.Effect
{
/* No available fields */
}Base class for effects using offscreen buffers
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.
Implementing a ClutterOffscreenEffect
Creating a sub-class of ClutterOffscreenEffect requires, in case
of overriding the ClutterEffect virtual functions, to chain up to the
ClutterOffscreenEffect‘s implementation.
On top of the ClutterEffect‘s virtual functions,
ClutterOffscreenEffect also provides a Clutter.OffscreenEffectClass.paint_target
function, which encapsulates the effective painting of the texture that
contains the result of the offscreen redirection.
The size of the target pipeline 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
Clutter.OffscreenEffectClass.create_texture virtual function; no chain up
to the ClutterOffscreenEffect implementation is required in this case.
Paint nodes
ClutterOffscreenEffect generates the following paint node tree:
Effect
├─────────┐
Layer Pipeline
│
Actor
When the actor contents are cached, the generated paint node tree looks like this:
Effect
│
Pipeline
In both cases, the “Pipeline” node is created with the return value
of Clutter.OffscreenEffectClass.create_pipeline.
Instance methods
clutter_offscreen_effect_create_texture
Calls the Clutter.OffscreenEffectClass.create_texture virtual function of the effect.
clutter_offscreen_effect_get_pipeline
Retrieves the pipeline used as a render target for the offscreen
buffer created by effect.
clutter_offscreen_effect_get_target_size
Retrieves the size of the offscreen buffer used by effect to
paint the actor to which it has been applied.
clutter_offscreen_effect_get_texture
Retrieves the texture used as a render target for the offscreen
buffer created by effect.
clutter_offscreen_effect_paint_target
Calls the Clutter.OffscreenEffectClass.paint_target virtual function of the effect.
Methods inherited from ClutterEffect (1)
clutter_effect_queue_repaint
Queues a repaint of the effect. The effect can detect when the ‘paint’
method is called as a result of this function because it will not
have the CLUTTER_EFFECT_PAINT_ACTOR_DIRTY flag set. In that case the
effect is free to assume that the actor has not changed its
appearance since the last time it was painted so it doesn’t need to
call clutter_actor_continue_paint() if it can draw a cached
image. This is mostly intended for effects that are using a
%CoglOffscreen to redirect the actor (such as
%ClutterOffscreenEffect). In that case the effect can save a bit of
rendering time by painting the cached texture without causing the
entire actor to be painted.
Methods inherited from ClutterActorMeta (5)
clutter_actor_meta_get_actor
Retrieves a pointer to the ClutterActor that owns meta.
clutter_actor_meta_get_enabled
Retrieves whether meta is enabled.
clutter_actor_meta_get_name
Retrieves the name set using clutter_actor_meta_set_name().
clutter_actor_meta_set_enabled
Sets whether meta should be enabled or not.
clutter_actor_meta_set_name
Sets the name of meta.
Properties
Properties inherited from ClutterActorMeta (3)
Clutter.ActorMeta:actor
The ClutterActor attached to the ClutterActorMeta instance.
Clutter.ActorMeta:enabled
Whether or not the ClutterActorMeta is enabled.
Clutter.ActorMeta:name
The unique name to access the ClutterActorMeta.
Signals
Signals inherited from GObject (1)
GObject::notify
The notify signal is emitted on an object when one of its properties has its value set through g_object_set_property(), g_object_set(), et al.
Class structure
struct ClutterOffscreenEffectClass {
CoglTexture* (* create_texture) (
ClutterOffscreenEffect* effect,
CoglContext* cogl_context,
gfloat width,
gfloat height
);
CoglPipeline* (* create_pipeline) (
ClutterOffscreenEffect* effect,
CoglTexture* texture
);
void (* paint_target) (
ClutterOffscreenEffect* effect,
ClutterPaintNode* node,
ClutterPaintContext* paint_context
);
}The ClutterOffscreenEffectClass structure contains only private data.
Class members
create_texture: CoglTexture* (* create_texture) ( ClutterOffscreenEffect* effect, CoglContext* cogl_context, gfloat width, gfloat height )Virtual function.
create_pipeline: CoglPipeline* (* create_pipeline) ( ClutterOffscreenEffect* effect, CoglTexture* texture )No description available.
paint_target: void (* paint_target) ( ClutterOffscreenEffect* effect, ClutterPaintNode* node, ClutterPaintContext* paint_context )Virtual function.
Virtual methods
Clutter.OffscreenEffectClass.create_texture
Calls the Clutter.OffscreenEffectClass.create_texture virtual function of the effect.
Clutter.OffscreenEffectClass.paint_target
Calls the Clutter.OffscreenEffectClass.paint_target virtual function of the effect.