shader-effect: Allow instantiating ShaderEffect

ClutterShaderEffect doesn't require to be sub-classed in order to be
useful. It is possible to just create an instance, set the source and
the uniforms, and attach it to an actor. This should effectively replace
ClutterShader for good.

clutter/clutter-shader-effect.c

@@ -27,11 +27,11 @@
  * @short_description: Base class for shader effects
  * @See_Also: #ClutterEffect, #ClutterOffscreenEffect
  *
- * #ClutterShaderEffect is an abstract class that implements all the
+ * #ClutterShaderEffect is a class that implements all the plumbing for
- * plumbing for creating #ClutterEffect<!-- -->s using GLSL shaders.
+ * creating #ClutterEffect<!-- -->s using GLSL shaders.
  *
- * #ClutterShaderEffect creates an offscreen buffer and then applies the GLSL
+ * #ClutterShaderEffect creates an offscreen buffer and then applies the
- * shader (after checking whether the compilation and linking were
+ * GLSL shader (after checking whether the compilation and linking were
  * successfull) to the buffer before painting it on screen.
  *
  * <refsect2 id="ClutterShaderEffect-implementing">
@@ -150,7 +150,7 @@ enum
 
 static GParamSpec *obj_props[PROP_LAST];
 
-G_DEFINE_ABSTRACT_TYPE (ClutterShaderEffect,
+G_DEFINE_TYPE (ClutterShaderEffect,
                clutter_shader_effect,
                CLUTTER_TYPE_OFFSCREEN_EFFECT);
 
@@ -437,6 +437,30 @@ clutter_shader_effect_init (ClutterShaderEffect *effect)
                                               ClutterShaderEffectPrivate);
 }
 
+/**
+ * clutter_shader_effect_new:
+ * @shader_type: the type of the shader, either %CLUTTER_FRAGMENT_SHADER,
+ *   or %CLUTTER_VERTEX_SHADER
+ *
+ * Creates a new #ClutterShaderEffect, to be applied to an actor using
+ * clutter_actor_add_effect().
+ *
+ * The effect will be empty until clutter_shader_effect_set_shader_source()
+ * is called.
+ *
+ * Return value: (transfer full): the newly created #ClutterShaderEffect.
+ *   Use g_object_unref() when done.
+ *
+ * Since: 1.8
+ */
+ClutterEffect *
+clutter_shader_effect_new (ClutterShaderType shader_type)
+{
+  return g_object_new (CLUTTER_TYPE_SHADER_EFFECT,
+                       "shader-type", shader_type,
+                       NULL);
+}
+
 /**
  * clutter_shader_effect_get_shader:
  * @effect: a #ClutterShaderEffect
@@ -547,6 +571,9 @@ clutter_shader_effect_add_uniform (ClutterShaderEffect *effect,
       uniform->location =
         cogl_program_get_uniform_location (priv->program, uniform->name);
     }
+
+  if (priv->actor != NULL && !CLUTTER_ACTOR_IN_PAINT (priv->actor))
+    clutter_actor_queue_redraw (priv->actor);
 }
 
 /**

clutter/clutter-shader-effect.h

@@ -84,6 +84,8 @@ struct _ClutterShaderEffectClass
 
 GType clutter_shader_effect_get_type (void) G_GNUC_CONST;
 
+ClutterEffect * clutter_shader_effect_new               (ClutterShaderType    shader_type);
+
 gboolean        clutter_shader_effect_set_shader_source (ClutterShaderEffect *effect,
                                                          const gchar         *source);