From 06bf2ddaefa5874d55358b80bc4bf03563784199 Mon Sep 17 00:00:00 2001
From: Tomas Frydrych <tf@openedhand.com>
Date: Wed, 16 May 2007 13:53:39 +0000
Subject: [PATCH] added clutter_sine_half_func()

---
 ChangeLog                          |  7 ++++++
 clutter/clutter-alpha.c            | 34 ++++++++++++++++++++++++++++++
 clutter/clutter-alpha.h            |  3 +++
 doc/reference/clutter-sections.txt |  2 ++
 4 files changed, 46 insertions(+)

diff --git a/ChangeLog b/ChangeLog
index 8ba46d3c5..95d98e058 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2007-05-16  Tomas Frydrych  <tf@openedhand.com>
+	
+	* clutter/clutter-alpha.h:
+	* clutter/clutter-alpha.c:
+	* doc/reference/clutter-sections.txt:
+	Added clutter_sine_half().
+	
 2007-05-16  Tomas Frydrych  <tf@openedhand.com>
 	
 	* clutter/clutter-alpha.h:
diff --git a/clutter/clutter-alpha.c b/clutter/clutter-alpha.c
index adadf6b74..4a17cb150 100644
--- a/clutter/clutter-alpha.c
+++ b/clutter/clutter-alpha.c
@@ -666,6 +666,40 @@ clutter_sine_dec_func (ClutterAlpha *alpha,
   return CFX_INT (sine);
 }
 
+/**
+ * clutter_sine_half_func:
+ * @alpha: a #ClutterAlpha
+ * @dummy: unused argument
+ *
+ * Convenience alpha function for a sine wave over interval <0, pi>.
+ * You can use this function as the alpha function for
+ * clutter_alpha_set_func().
+ *
+ * Return value: an alpha value.
+ *
+ * Since: 0.4
+ */
+guint32 
+clutter_sine_half_func (ClutterAlpha *alpha,
+			gpointer      dummy)
+{
+  ClutterTimeline * timeline;
+  gint              frame;
+  gint              n_frames;
+  ClutterAngle      x;
+  ClutterFixed      sine;
+  
+  timeline = clutter_alpha_get_timeline (alpha);
+  frame    = clutter_timeline_get_current_frame (timeline);
+  n_frames = clutter_timeline_get_n_frames (timeline);
+
+  x = 512 * frame / n_frames;
+
+  sine = clutter_sini (x) * CLUTTER_ALPHA_MAX_ALPHA;
+
+  return CFX_INT (sine);
+}
+
 /**
  * clutter_square_func:
  * @alpha: a #ClutterAlpha
diff --git a/clutter/clutter-alpha.h b/clutter/clutter-alpha.h
index fb4d40e01..ac1c14e1a 100644
--- a/clutter/clutter-alpha.h
+++ b/clutter/clutter-alpha.h
@@ -108,6 +108,7 @@ ClutterTimeline *clutter_alpha_get_timeline (ClutterAlpha     *alpha);
 #define CLUTTER_ALPHA_SINE       clutter_sine_func
 #define CLUTTER_ALPHA_SINE_INC   clutter_sine_inc_func
 #define CLUTTER_ALPHA_SINE_DEC   clutter_sine_dec_func
+#define CLUTTER_ALPHA_SINE_HALF  clutter_sine_half_func
 #define CLUTTER_ALPHA_SQUARE     clutter_square_func
 #define CLUTTER_ALPHA_SMOOTHSTEP clutter_smoothstep_func
 
@@ -137,6 +138,8 @@ guint32             clutter_sine_inc_func      (ClutterAlpha     *alpha,
 						gpointer          dummy);
 guint32             clutter_sine_dec_func      (ClutterAlpha     *alpha,
 						gpointer          dummy);
+guint32             clutter_sine_half_func     (ClutterAlpha     *alpha,
+						gpointer          dummy);
 guint32             clutter_square_func        (ClutterAlpha     *alpha,
 						gpointer          dummy);
 guint32             clutter_smoothstep_func    (ClutterAlpha     *alpha,
diff --git a/doc/reference/clutter-sections.txt b/doc/reference/clutter-sections.txt
index 1621337e8..fae4b6979 100644
--- a/doc/reference/clutter-sections.txt
+++ b/doc/reference/clutter-sections.txt
@@ -116,6 +116,8 @@ CLUTTER_ALPHA_SINE_INC
 clutter_sine_inc_func
 CLUTTER_ALPHA_SINE_DEC
 clutter_sine_dec_func
+CLUTTER_ALPHA_SINE_HALF
+clutter_sine_half_func
 CLUTTER_ALPHA_SQUARE
 clutter_square_func
 CLUTTER_ALPHA_SMOOTHSTEP