From 2022e4c100d8d8e635ea38d990d6023f7306020f Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Mon, 4 Apr 2011 18:42:52 +0100
Subject: [PATCH] clutter-stage: Don't override the user's perspective matrix

Since eef9078f ClutterStage updates the aspect ratio of the
perspective matrix whenever the size of the stage changes. This meant
that if an application tries to set its own perspective matrix then
part of it would get overridden. It's not really clear what the
use-case of setting the perspective on the stage should be but it
seems like the safest bet is to always try to preserve the
application's request. The documentation for the function has been
tweaked to discourage its use.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2625
---
 clutter/clutter-stage.c | 62 ++++++++++++++++++++++++++++-------------
 1 file changed, 43 insertions(+), 19 deletions(-)

diff --git a/clutter/clutter-stage.c b/clutter/clutter-stage.c
index 6373d8b0f..e231440f4 100644
--- a/clutter/clutter-stage.c
+++ b/clutter/clutter-stage.c
@@ -176,6 +176,7 @@ struct _ClutterStagePrivate
   guint have_valid_pick_buffer : 1;
   guint accept_focus           : 1;
   guint motion_events_enabled  : 1;
+  guint has_custom_perspective : 1;
 };
 
 enum
@@ -2136,24 +2137,11 @@ clutter_stage_get_color (ClutterStage *stage,
   *color = priv->color;
 }
 
-/**
- * clutter_stage_set_perspective:
- * @stage: A #ClutterStage
- * @perspective: A #ClutterPerspective
- *
- * Sets the stage perspective.
- */
-void
-clutter_stage_set_perspective (ClutterStage       *stage,
-                               ClutterPerspective *perspective)
+static void
+clutter_stage_set_perspective_internal (ClutterStage       *stage,
+                                        ClutterPerspective *perspective)
 {
-  ClutterStagePrivate *priv;
-
-  g_return_if_fail (CLUTTER_IS_STAGE (stage));
-  g_return_if_fail (perspective != NULL);
-  g_return_if_fail (perspective->z_far - perspective->z_near != 0);
-
-  priv = stage->priv;
+  ClutterStagePrivate *priv = stage->priv;
 
   if (priv->perspective.fovy == perspective->fovy &&
       priv->perspective.aspect == perspective->aspect &&
@@ -2176,6 +2164,35 @@ clutter_stage_set_perspective (ClutterStage       *stage,
   clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
 }
 
+/**
+ * clutter_stage_set_perspective:
+ * @stage: A #ClutterStage
+ * @perspective: A #ClutterPerspective
+ *
+ * Sets the stage perspective. Using this function is not recommended
+ * because it will disable Clutter's attempts to generate an
+ * appropriate perspective based on the size of the stage.
+ */
+void
+clutter_stage_set_perspective (ClutterStage       *stage,
+                               ClutterPerspective *perspective)
+{
+  ClutterStagePrivate *priv;
+
+  g_return_if_fail (CLUTTER_IS_STAGE (stage));
+  g_return_if_fail (perspective != NULL);
+  g_return_if_fail (perspective->z_far - perspective->z_near != 0);
+
+  priv = stage->priv;
+
+  /* If the application ever calls this function then we'll stop
+     automatically updating the perspective when the stage changes
+     size */
+  priv->has_custom_perspective = TRUE;
+
+  clutter_stage_set_perspective_internal (stage, perspective);
+}
+
 /**
  * clutter_stage_get_perspective:
  * @stage: A #ClutterStage
@@ -3134,8 +3151,15 @@ _clutter_stage_maybe_setup_viewport (ClutterStage *stage)
                          priv->viewport[3]);
 
       perspective = priv->perspective;
-      perspective.aspect = priv->viewport[2] / priv->viewport[3];
-      clutter_stage_set_perspective (stage, &perspective);
+
+      /* Ideally we want to regenerate the perspective matrix whenever
+         the size changes but if the user has provided a custom matrix
+         then we don't want to override it */
+      if (!priv->has_custom_perspective)
+        {
+          perspective.aspect = priv->viewport[2] / priv->viewport[3];
+          clutter_stage_set_perspective_internal (stage, &perspective);
+        }
 
       cogl_matrix_init_identity (&priv->view);
       cogl_matrix_view_2d_in_perspective (&priv->view,