From 829065f97ad506fc5daf12f301a964a68290f6ac Mon Sep 17 00:00:00 2001
From: Bruno Dilly <bdilly@profusion.mobi>
Date: Thu, 25 Oct 2012 21:55:23 +0000
Subject: [PATCH] ephysics: support disabling stacking based on Z axis

Since now we support movement on Z axis the evas objects
associated to bodies need to be re-stacked to be below / above
each other.

But if Z axis movement is disabled, no cloth is used, ...,
it can be safely disabled, since evas objects won't overlap.
And it will save performance.



SVN revision: 78491
---
 legacy/ephysics/src/lib/EPhysics.h         | 44 ++++++++++++++++++++++
 legacy/ephysics/src/lib/ephysics_world.cpp | 30 ++++++++++++++-
 2 files changed, 72 insertions(+), 2 deletions(-)

diff --git a/legacy/ephysics/src/lib/EPhysics.h b/legacy/ephysics/src/lib/EPhysics.h
index 4c2f64fe9c..b6d739bdd2 100644
--- a/legacy/ephysics/src/lib/EPhysics.h
+++ b/legacy/ephysics/src/lib/EPhysics.h
@@ -1523,6 +1523,50 @@ EAPI void ephysics_world_light_all_bodies_set(EPhysics_World *world, Eina_Bool e
  */
 EAPI Eina_Bool ephysics_world_light_all_bodies_get(const EPhysics_World *world);
 
+/**
+ * @brief
+ * Enable / disable stacking based on bodies z coordinates.
+ *
+ * Evas objects associated to bodies will be restacked when it's enabled.
+ * So if a body A has coordinates x = 10, y = 10, z = 8 and a body B
+ * has coordinates x = 10, y = 10, z = 10, the evas object associated to B
+ * will be displayed below the evas object associated to A.
+ *
+ * Evas objects will be restacked at each simulation tick. It's enabled by
+ * default, and disabling it can lead to wrong scenarios when movement
+ * on Z axis is enabled or when cloths are used.
+ *
+ * But disabling it can save performance, so if you won't face these
+ * scenarios, it safe to disable it, since no evas object will be moved to
+ * be below or above others.
+ *
+ * @param world The physics world.
+ * @param enabled If @c EINA_TRUE, stacking based on Z coordinates will be
+ * enabled, otherwise it will be disabled.
+ *
+ * @see ephysics_world_stack_enable_get()
+ * @see ephysics_body_evas_object_set()
+ *
+ * @ingroup EPhysics_World
+ */
+EAPI void ephysics_world_stack_enable_set(EPhysics_World *world, Eina_Bool enabled);
+
+/**
+ * @brief
+ * Get stacking status of world.
+ *
+ * Stacking based on bodies z coordinates can be enabled or disabled.
+ *
+ * @param world The physics world.
+ * @return @c EINA_TRUE if it's running, or @c EINA_FALSE if it's paused or on
+ * error.
+ *
+ * @see ephysics_world_stack_enable_set() for more details.
+ *
+ * @ingroup EPhysics_World
+ */
+EAPI Eina_Bool ephysics_world_stack_enable_get(const EPhysics_World *world);
+
 /**
  * @}
  */
diff --git a/legacy/ephysics/src/lib/ephysics_world.cpp b/legacy/ephysics/src/lib/ephysics_world.cpp
index 8900f69cb3..41d089eea7 100644
--- a/legacy/ephysics/src/lib/ephysics_world.cpp
+++ b/legacy/ephysics/src/lib/ephysics_world.cpp
@@ -101,6 +101,7 @@ struct _EPhysics_World {
      Eina_Bool outside_front:1;
      Eina_Bool outside_back:1;
      Eina_Bool pending_simulation:1;
+     Eina_Bool stacking:1;
 };
 
 static int _ephysics_world_init_count = 0;
@@ -242,7 +243,8 @@ _ephysics_world_tick(btDynamicsWorld *dynamics_world)
           }
      }
 
-   ephysics_body_evas_objects_restack(world);
+   if (world->stacking)
+     ephysics_body_evas_objects_restack(world);
 
    if (camera_moved)
      {
@@ -752,8 +754,9 @@ ephysics_world_new(void)
      INF("Couldn't initialize the collision filter.");
    else
      world->dynamics_world->getPairCache()->setOverlapFilterCallback(
-                                                               world->filter_cb);
+        world->filter_cb);
 
+   world->stacking = EINA_TRUE;
    world->rate = 30;
    world->max_sub_steps = 3;
    world->fixed_time_step = 1/60.f;
@@ -1627,6 +1630,29 @@ ephysics_world_light_all_bodies_get(const EPhysics_World *world)
    return world->light->all_bodies;
 }
 
+EAPI void
+ephysics_world_stack_enable_set(EPhysics_World *world, Eina_Bool enabled)
+{
+   if (!world)
+     {
+        ERR("Can't enable / disable stacking, world wasn't provided.");
+        return;
+     }
+   world->stacking = !!enabled;
+}
+
+EAPI Eina_Bool
+ephysics_world_stack_enable_get(const EPhysics_World *world)
+{
+   if (!world)
+     {
+	ERR("No world, no stacking status for you.");
+	return EINA_FALSE;
+     }
+
+   return world->stacking;
+}
+
 #ifdef  __cplusplus
 }
 #endif