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 ClutterOffscreenEffects 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 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 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.

Hierarchy

hierarchy this ClutterOffscreenEffect ancestor_0 ClutterEffect ancestor_0--this ancestor_1 ClutterActorMeta ancestor_1--ancestor_0 ancestor_2 GInitiallyUnowned ancestor_2--ancestor_1 ancestor_3 GObject ancestor_3--ancestor_2

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.

Methods inherited from GObject (43)

Please see GObject for a full list of methods.

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,
    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, gfloat width, gfloat height )

No description available.

create_pipeline: CoglPipeline* (* create_pipeline) ( ClutterOffscreenEffect* effect, CoglTexture* texture )

No description available.

paint_target: void (* paint_target) ( ClutterOffscreenEffect* effect, ClutterPaintNode* node, ClutterPaintContext* paint_context )

No description available.

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.