[mutter] MetaBackgroundActor: add a setter for GLSL uniforms

[Giovanni Campagna <gcampagna src gnome org>]

commit e73946f0bf0ba6a77cf48ce2bd9e1bd12dfb6ff2
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Wed Nov 7 19:00:25 2012 +0100

    MetaBackgroundActor: add a setter for GLSL uniforms
    
    It doesn't make sense to GLSL shaders without uniforms.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=682536

 src/compositor/meta-background-actor.c |   35 ++++++++++++++++++++++++++++++++
 src/meta/meta-background-actor.h       |    7 ++++++
 2 files changed, 42 insertions(+), 0 deletions(-)
---
diff --git a/src/compositor/meta-background-actor.c b/src/compositor/meta-background-actor.c
index 0f5840d..b039b58 100644
--- a/src/compositor/meta-background-actor.c
+++ b/src/compositor/meta-background-actor.c
@@ -668,3 +668,38 @@ meta_background_actor_add_glsl_snippet (MetaBackgroundActor *actor,
   cogl_object_unref (snippet);
 }
 
+/**
+ * meta_background_actor_set_uniform_float:
+ * @actor: a #MetaBackgroundActor
+ * @uniform_name:
+ * @n_components: number of components (for vector uniforms)
+ * @count: number of uniforms (for array uniforms)
+ * @uniform: (array length=uniform_length): the float values to set
+ * @uniform_length: the length of @uniform. Must be exactly @n_components x @count,
+ *                  and is provided mainly for language bindings.
+ *
+ * Sets a new GLSL uniform to the provided value. This is mostly
+ * useful in congiunction with meta_background_actor_add_glsl_snippet().
+ */
+
+void
+meta_background_actor_set_uniform_float (MetaBackgroundActor *actor,
+                                         const char          *uniform_name,
+                                         int                  n_components,
+                                         int                  count,
+                                         const float         *uniform,
+                                         int                  uniform_length)
+{
+  MetaBackgroundActorPrivate *priv;
+
+  g_return_if_fail (META_IS_BACKGROUND_ACTOR (actor));
+  g_return_if_fail (uniform_length == n_components * count);
+
+  priv = actor->priv;
+
+  cogl_pipeline_set_uniform_float (priv->pipeline,
+                                   cogl_pipeline_get_uniform_location (priv->pipeline,
+                                                                       uniform_name),
+                                   n_components, count, uniform);
+}
+
diff --git a/src/meta/meta-background-actor.h b/src/meta/meta-background-actor.h
index 6efcc25..71831af 100644
--- a/src/meta/meta-background-actor.h
+++ b/src/meta/meta-background-actor.h
@@ -90,4 +90,11 @@ void meta_background_actor_add_glsl_snippet (MetaBackgroundActor *actor,
                                              const char          *code,
                                              gboolean             is_replace);
 
+void meta_background_actor_set_uniform_float (MetaBackgroundActor *actor,
+                                              const char          *uniform_name,
+                                              int                  n_components,
+                                              int                  count,
+                                              const float         *uniform,
+                                              int                  uniform_length);
+
 #endif /* META_BACKGROUND_ACTOR_H */