[mutter] clutter/stage: Remove ability to set custom perspective

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 08431a127a8c22adc2b90be95ee0db4d307728dd
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Apr 3 19:01:04 2020 +0200

    clutter/stage: Remove ability to set custom perspective
    
    Unused, and complicates things, so drop it.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1175

 clutter/clutter/clutter-stage.c | 81 +++++++++--------------------------------
 clutter/clutter/clutter-stage.h |  6 +--
 2 files changed, 19 insertions(+), 68 deletions(-)
---
diff --git a/clutter/clutter/clutter-stage.c b/clutter/clutter/clutter-stage.c
index 0b364638f..fc037662c 100644
--- a/clutter/clutter/clutter-stage.c
+++ b/clutter/clutter/clutter-stage.c
@@ -146,7 +146,6 @@ struct _ClutterStagePrivate
   guint throttle_motion_events : 1;
   guint min_size_changed       : 1;
   guint motion_events_enabled  : 1;
-  guint has_custom_perspective : 1;
   guint stage_was_relayout     : 1;
 };
 
@@ -1843,10 +1842,6 @@ clutter_stage_set_property (GObject      *object,
                                           clutter_value_get_color (value));
       break;
 
-    case PROP_PERSPECTIVE:
-      clutter_stage_set_perspective (stage, g_value_get_boxed (value));
-      break;
-
     case PROP_TITLE:
       clutter_stage_set_title (stage, g_value_get_string (value));
       break;
@@ -2026,7 +2021,7 @@ clutter_stage_class_init (ClutterStageClass *klass)
                           P_("Perspective"),
                           P_("Perspective projection parameters"),
                           CLUTTER_TYPE_PERSPECTIVE,
-                          CLUTTER_PARAM_READWRITE);
+                          CLUTTER_PARAM_READABLE);
 
   /**
    * ClutterStage:title:
@@ -2355,8 +2350,8 @@ clutter_stage_get_color (ClutterStage *stage,
 }
 
 static void
-clutter_stage_set_perspective_internal (ClutterStage       *stage,
-                                        ClutterPerspective *perspective)
+clutter_stage_set_perspective (ClutterStage       *stage,
+                               ClutterPerspective *perspective)
 {
   ClutterStagePrivate *priv = stage->priv;
 
@@ -2381,36 +2376,6 @@ clutter_stage_set_perspective_internal (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_update_view_perspective (stage);
-}
-
 /**
  * clutter_stage_get_perspective:
  * @stage: A #ClutterStage
@@ -2437,7 +2402,7 @@ clutter_stage_get_perspective (ClutterStage       *stage,
  *              @stage.
  *
  * Retrieves the @stage's projection matrix. This is derived from the
- * current perspective set using clutter_stage_set_perspective().
+ * current perspective.
  *
  * Since: 1.6
  */
@@ -3152,30 +3117,20 @@ clutter_stage_update_view_perspective (ClutterStage *stage)
 
   perspective = priv->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.fovy = 60.0; /* 60 Degrees */
-      perspective.z_near = 0.1;
-      perspective.aspect = priv->viewport[2] / priv->viewport[3];
-      z_2d = calculate_z_translation (perspective.z_near);
-
-      /* NB: z_2d is only enough room for 85% of the stage_height between
-       * the stage and the z_near plane. For behind the stage plane we
-       * want a more consistent gap of 10 times the stage_height before
-       * hitting the far plane so we calculate that relative to the final
-       * height of the stage plane at the z_2d_distance we got... */
-      perspective.z_far = z_2d +
-        tanf (_DEG_TO_RAD (perspective.fovy / 2.0f)) * z_2d * 20.0f;
-
-      clutter_stage_set_perspective_internal (stage, &perspective);
-    }
-  else
-    {
-      z_2d = calculate_z_translation (perspective.z_near);
-    }
+  perspective.fovy = 60.0; /* 60 Degrees */
+  perspective.z_near = 0.1;
+  perspective.aspect = priv->viewport[2] / priv->viewport[3];
+  z_2d = calculate_z_translation (perspective.z_near);
+
+  /* NB: z_2d is only enough room for 85% of the stage_height between
+   * the stage and the z_near plane. For behind the stage plane we
+   * want a more consistent gap of 10 times the stage_height before
+   * hitting the far plane so we calculate that relative to the final
+   * height of the stage plane at the z_2d_distance we got... */
+  perspective.z_far = z_2d +
+    tanf (_DEG_TO_RAD (perspective.fovy / 2.0f)) * z_2d * 20.0f;
+
+  clutter_stage_set_perspective (stage, &perspective);
 
   cogl_matrix_init_identity (&priv->view);
   cogl_matrix_view_2d_in_perspective (&priv->view,
diff --git a/clutter/clutter/clutter-stage.h b/clutter/clutter/clutter-stage.h
index a86af3de8..d89f7c8d7 100644
--- a/clutter/clutter/clutter-stage.h
+++ b/clutter/clutter/clutter-stage.h
@@ -103,8 +103,7 @@ struct _ClutterStageClass
  * @z_far: the distance from the viewer to the far clipping
  *   plane (always positive)
  *
- * Stage perspective definition. #ClutterPerspective is only used by
- * the fixed point version of clutter_stage_set_perspective().
+ * Stage perspective definition.
  *
  * Since: 0.4
  */
@@ -140,9 +139,6 @@ GType clutter_stage_get_type (void) G_GNUC_CONST;
 CLUTTER_EXPORT
 ClutterActor *  clutter_stage_new                               (void);
 
-CLUTTER_EXPORT
-void            clutter_stage_set_perspective                   (ClutterStage          *stage,
-                                                                ClutterPerspective    *perspective);
 CLUTTER_EXPORT
 void            clutter_stage_get_perspective                   (ClutterStage          *stage,
                                                                 ClutterPerspective    *perspective);