add labels and ordering for transform and parent systems in POST_UPDATE stage (#1456)

Author: mockersf

crates/bevy_transform/src/lib.rs

@@ -8,6 +8,7 @@ pub mod prelude {
 
 use bevy_app::{prelude::*, startup_stage};
 use bevy_ecs::IntoSystem;
+use bevy_ecs::ParallelSystemDescriptorCoercion;
 use bevy_reflect::RegisterTypeBuilder;
 use prelude::{parent_update_system, Children, GlobalTransform, Parent, PreviousParent, Transform};
 
@@ -22,15 +23,27 @@ impl Plugin for TransformPlugin {
             .register_type::<Transform>()
             .register_type::<GlobalTransform>()
             // add transform systems to startup so the first update is "correct"
-            .add_startup_system_to_stage(startup_stage::POST_STARTUP, parent_update_system.system())
             .add_startup_system_to_stage(
                 startup_stage::POST_STARTUP,
-                transform_propagate_system::transform_propagate_system.system(),
+                parent_update_system.system().label("parent_update_system"),
+            )
+            .add_startup_system_to_stage(
+                startup_stage::POST_STARTUP,
+                transform_propagate_system::transform_propagate_system
+                    .system()
+                    .label("transform_propagate_system")
+                    .after("parent_update_system"),
+            )
+            .add_system_to_stage(
+                stage::POST_UPDATE,
+                parent_update_system.system().label("parent_update_system"),
             )
-            .add_system_to_stage(stage::POST_UPDATE, parent_update_system.system())
             .add_system_to_stage(
                 stage::POST_UPDATE,
-                transform_propagate_system::transform_propagate_system.system(),
+                transform_propagate_system::transform_propagate_system
+                    .system()
+                    .label("transform_propagate_system")
+                    .after("parent_update_system"),
             );
     }
 }