[clutter] docs: Document the DeformEffect wrap-mode change

[Emmanuele Bassi <ebassi src gnome org>]

commit ebf12a8cd724ff5136021d4b3aaa6e61531620d4
Author: Emmanuele Bassi <ebassi linux intel com>
Date:   Wed Nov 16 16:42:41 2011 +0000

    docs: Document the DeformEffect wrap-mode change
    
    The change from CoglVertexBuffer to CoglPrimitive led to a change of the
    default wrap-mode for the pipeline. Since using REPEAT can introduce
    artifacts when sampling outside the [ 0, 1 ] texture coordinates range,
    and since the default wrap mode was not documented anyway, we want to
    keep the change from REPEAT to CLAMP, but it's worth adding an entry in
    the release notes.

 README.in |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/README.in b/README.in
index 433de68..9ab556a 100644
--- a/README.in
+++ b/README.in
@@ -289,6 +289,16 @@ features).
 Release Notes for Clutter 1.10
 -------------------------------------------------------------------------------
 
+â ClutterDeformEffect switched from using CoglVertexBuffer to using the
+  CoglPrimitive API internally, to improve performance and use non-deprecated
+  Cogl API. CoglPrimitive converts COGL_WRAP_MODE_AUTOMATIC to
+  COGL_WRAP_MODE_CLAMP_TO_EDGE, unlike CoglVertexBuffer which converts it to
+  COGL_WRAP_MODE_REPEAT. This prevents artifacts when sampling texture
+  coordinates outside the [ 0, 1 ] range. This change may cause the back
+  texture to not be painted if its coordinates go outside the allowed range,
+  for instance when using a custom transformation matrix on the back material
+  used by the ClutterDeformEffect.
+
 â The "default stage" has been deprecated; since the 1.0 release, the default
   stage creation was deferred to the call to clutter_stage_get_default(), and
   the preferred way for getting a ClutterStage was calling clutter_stage_new()