[scene] Manage scene roots in transform

Since transforms now know the scene to which they belong, and they know
when they are root and when not, getting the transform code to manage
the scene roots is the best way to keep the list of root transforms
consistent.

include/scn_internal.h

@@ -11,4 +11,7 @@ typedef struct scene_resources_s {
 	PR_RESMAP (transform_t) transforms;
 } scene_resources_t;
 
+void scene_add_root (scene_t *scene, transform_t *transform);
+void scene_del_root (scene_t *scene, transform_t *transform);
+
 #endif//__scn_internal_h

libs/scene/scene.c

@@ -88,7 +88,6 @@ Scene_CreateEntity (scene_t *scene)
 	hierarchy_t *h = ent->transform->hierarchy;
 	h->entity.a[ent->transform->index] = ent;
 
-	DARRAY_APPEND (&scene->roots, ent->transform);
 	return ent;
 }
 
@@ -99,8 +98,16 @@ Scene_GetEntity (scene_t *scene, int id)
 	return PR_RESGET (res->entities, id);
 }
 
-static void
+void
-unroot_transform (scene_t *scene, transform_t *transform)
+scene_add_root (scene_t *scene, transform_t *transform)
+{
+	if (!Transform_GetParent (transform)) {
+		DARRAY_APPEND (&scene->roots, transform);
+	}
+}
+
+void
+scene_del_root (scene_t *scene, transform_t *transform)
 {
 	if (!Transform_GetParent (transform)) {
 		for (size_t i = 0; i < scene->roots.size; i++) {
@@ -138,7 +145,6 @@ Scene_DestroyEntity (scene_t *scene, entity_t *ent)
 	if (PR_RESGET (res->entities, ent->id) != ent) {
 		Sys_Error ("Scene_DestroyEntity: entity not owned by scene");
 	}
-	unroot_transform (scene, ent->transform);
 	// pull the transform out of the hierarchy to make it easier to destory
 	// all the child entities
 	Transform_SetParent (ent->transform, 0);

libs/scene/transform.c

@@ -58,6 +58,7 @@ Transform_New (scene_t *scene, transform_t *parent)
 	} else {
 		transform->hierarchy = Hierarchy_New (16, 1);//FIXME should be config
 		transform->index = 0;
+		scene_add_root (scene, transform);
 	}
 	transform->hierarchy->transform.a[transform->index] = transform;
 	Hierarchy_UpdateMatrices (transform->hierarchy);
@@ -72,6 +73,7 @@ Transform_Delete (transform_t *transform)
 		// hierarchy so deleting it is easier
 		Transform_SetParent (transform, 0);
 	}
+	scene_del_root (transform->scene, transform);
 	Hierarchy_Delete (transform->hierarchy);
 }
 
@@ -87,6 +89,7 @@ void
 Transform_SetParent (transform_t *transform, transform_t *parent)
 {
 	if (parent) {
+		scene_del_root (transform->scene, transform);
 		hierarchy_t *hierarchy = transform->hierarchy;
 		uint32_t    index = transform->index;
 		Hierarchy_InsertHierarchy (parent->hierarchy, hierarchy,
@@ -108,6 +111,7 @@ Transform_SetParent (transform_t *transform, transform_t *parent)
 		Hierarchy_InsertHierarchy (new_hierarchy, hierarchy, null_transform,
 								   index);
 		Hierarchy_RemoveHierarchy (hierarchy, index);
+		scene_add_root (transform->scene, transform);
 	}
 }