Class

ClutterShaderEffect

Description [src]

class Clutter.ShaderEffect : Clutter.OffscreenEffect
{
  /* No available fields */
}

Base class for shader effects

ClutterShaderEffect is a class that implements all the plumbing for creating ClutterEffects using GLSL shaders.

ClutterShaderEffect creates an offscreen buffer and then applies the GLSL shader (after checking whether the compilation and linking were successful) to the buffer before painting it on screen.

Implementing a ClutterShaderEffect

Creating a sub-class of ClutterShaderEffect requires the overriding of the Clutter.OffscreenEffectClass.paint_target virtual function from the ClutterOffscreenEffect class. It is also convenient to implement the Clutter.ShaderEffectClass.get_static_shader_source virtual function in case you are planning to create more than one instance of the effect.

The Clutter.ShaderEffectClass.get_static_shader_source function should return a copy of the shader source to use. This function is only called once per subclass of ClutterShaderEffect regardless of how many instances of the effect are created. The source for the shader is typically stored in a static const string which is returned from this function via g_strdup().

The Clutter.OffscreenEffectClass.paint_target should set the shader’s uniforms if any. This is done by calling clutter_shader_effect_set_uniform_value() or clutter_shader_effect_set_uniform(). The sub-class should then chain up to the ClutterShaderEffect implementation.

Setting uniforms on a ClutterShaderEffect

The example below shows a typical implementation of the Clutter.ShaderEffectClass.get_static_shader_source and Clutter.OffscreenEffectClass.paint_target virtual functions for a ClutterShaderEffect subclass.

 static gchar *
 my_effect_get_static_shader_source (ClutterShaderEffect *effect)
 {
   // shader_source is set elsewhere
   return g_strdup (shader_source);
 }

 static gboolean
 my_effect_paint_target (ClutterOffscreenEffect *effect)
 {
   MyEffect *self = MY_EFFECT (effect);
   ClutterShaderEffect *shader = CLUTTER_SHADER_EFFECT (effect);
   ClutterEffectClass *parent_class;
   gfloat component_r, component_g, component_b;

   // the "tex" uniform is declared in the shader as:
   //
   //   uniform int tex;
   //
   // and it is passed a constant value of 0
   clutter_shader_effect_set_uniform (shader, "tex", G_TYPE_INT, 1, 0);

   // the "component" uniform is declared in the shader as:
   //
   //   uniform vec3 component;
   //
   // and it's defined to contain the normalized components
   // of a #ClutterColor
   component_r = self->color.red   / 255.0f;
   component_g = self->color.green / 255.0f;
   component_b = self->color.blue  / 255.0f;
   clutter_shader_effect_set_uniform (shader, "component",
                                      G_TYPE_FLOAT, 3,
                                      component_r,
                                      component_g,
                                      component_b);

   // chain up to the parent's implementation
   parent_class = CLUTTER_OFFSCREEN_EFFECT_CLASS (my_effect_parent_class);
   return parent_class->paint_target (effect);
 }

Hierarchy

hierarchy this ClutterShaderEffect ancestor_0 ClutterOffscreenEffect ancestor_0--this ancestor_1 ClutterEffect ancestor_1--ancestor_0 ancestor_2 ClutterActorMeta ancestor_2--ancestor_1 ancestor_3 GInitiallyUnowned ancestor_3--ancestor_2 ancestor_4 GObject ancestor_4--ancestor_3

Constructors

clutter_shader_effect_new

Creates a new ClutterShaderEffect, to be applied to an actor using clutter_actor_add_effect().

Instance methods

clutter_shader_effect_get_program

Retrieves a pointer to the program’s handle.

clutter_shader_effect_get_shader

Retrieves a pointer to the shader’s handle.

clutter_shader_effect_set_shader_source

Sets the source of the GLSL shader used by effect.

clutter_shader_effect_set_uniform

Sets a list of values as the payload for the uniform name inside the shader effect.

clutter_shader_effect_set_uniform_value

Sets value as the payload for the uniform name inside the shader effect.

Methods inherited from ClutterOffscreenEffect (5)
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

Clutter.ShaderEffect:shader-type

The type of shader that is used by the effect. This property should be set by the constructor of ClutterShaderEffect sub-classes.

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 ClutterShaderEffectClass {
  gchar* (* get_static_shader_source) (
    ClutterShaderEffect* effect
  );
  
}

The ClutterShaderEffectClass structure contains only private data.

Class members
get_static_shader_source: gchar* (* get_static_shader_source) ( ClutterShaderEffect* effect )

No description available.

Virtual methods