diff --git a/headers/enduro2d/high/_all.hpp b/headers/enduro2d/high/_all.hpp
index 8fdf9090..64424fa1 100644
--- a/headers/enduro2d/high/_all.hpp
+++ b/headers/enduro2d/high/_all.hpp
@@ -42,7 +42,7 @@
 #include "systems/flipbook_system.hpp"
 #include "systems/label_system.hpp"
 #include "systems/render_system.hpp"
-#include "systems/spine_systems.hpp"
+#include "systems/spine_system.hpp"
 
 #include "address.hpp"
 #include "asset.hpp"
diff --git a/headers/enduro2d/high/_high.hpp b/headers/enduro2d/high/_high.hpp
index 2e239c2f..64529eda 100644
--- a/headers/enduro2d/high/_high.hpp
+++ b/headers/enduro2d/high/_high.hpp
@@ -54,8 +54,7 @@ namespace e2d
     class flipbook_system;
     class label_system;
     class render_system;
-    class spine_pre_system;
-    class spine_post_system;
+    class spine_system;
 
     template < typename Asset, typename Content >
     class content_asset;
diff --git a/headers/enduro2d/high/systems/_systems.hpp b/headers/enduro2d/high/systems/_systems.hpp
new file mode 100644
index 00000000..4be97855
--- /dev/null
+++ b/headers/enduro2d/high/systems/_systems.hpp
@@ -0,0 +1,37 @@
+/*******************************************************************************
+ * This file is part of the "Enduro2D"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2018-2019, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#pragma once
+
+#include "../_high.hpp"
+
+namespace e2d::systems
+{
+    struct update_event {
+        f32 dt{0.f};
+        f32 time{0.f};
+    };
+
+    struct pre_update_event {
+        f32 dt{0.f};
+        f32 time{0.f};
+    };
+
+    struct post_update_event {
+        f32 dt{0.f};
+        f32 time{0.f};
+    };
+
+    struct render_event {};
+    struct pre_render_event {};
+    struct post_render_event {};
+
+    using update_system = ecs::system<update_event>;
+    using post_update_system = ecs::system<post_update_event>;
+
+    using render_system = ecs::system<render_event>;
+    using post_render_system = ecs::system<post_render_event>;
+}
diff --git a/headers/enduro2d/high/systems/flipbook_system.hpp b/headers/enduro2d/high/systems/flipbook_system.hpp
index 1f9d383b..740ac909 100644
--- a/headers/enduro2d/high/systems/flipbook_system.hpp
+++ b/headers/enduro2d/high/systems/flipbook_system.hpp
@@ -6,15 +6,19 @@
 
 #pragma once
 
-#include "../_high.hpp"
+#include "_systems.hpp"
 
 namespace e2d
 {
-    class flipbook_system final : public ecs::system {
+    class flipbook_system final
+        : public ecs::system<ecs::after<systems::update_event>> {
     public:
         flipbook_system();
-        ~flipbook_system() noexcept final;
-        void process(ecs::registry& owner) override;
+        ~flipbook_system() noexcept;
+
+        void process(
+            ecs::registry& owner,
+            const ecs::after<systems::update_event>& trigger) override;
     private:
         class internal_state;
         std::unique_ptr<internal_state> state_;
diff --git a/headers/enduro2d/high/systems/label_system.hpp b/headers/enduro2d/high/systems/label_system.hpp
index 89928a5e..57d672c5 100644
--- a/headers/enduro2d/high/systems/label_system.hpp
+++ b/headers/enduro2d/high/systems/label_system.hpp
@@ -6,15 +6,19 @@
 
 #pragma once
 
-#include "../_high.hpp"
+#include "_systems.hpp"
 
 namespace e2d
 {
-    class label_system final : public ecs::system {
+    class label_system final
+        : public ecs::system<ecs::after<systems::update_event>> {
     public:
         label_system();
         ~label_system() noexcept final;
-        void process(ecs::registry& owner) override;
+
+        void process(
+            ecs::registry& owner,
+            const ecs::after<systems::update_event>& trigger) override;
     private:
         class internal_state;
         std::unique_ptr<internal_state> state_;
diff --git a/headers/enduro2d/high/systems/render_system.hpp b/headers/enduro2d/high/systems/render_system.hpp
index 60f11963..c8cb2d74 100644
--- a/headers/enduro2d/high/systems/render_system.hpp
+++ b/headers/enduro2d/high/systems/render_system.hpp
@@ -6,15 +6,19 @@
 
 #pragma once
 
-#include "../_high.hpp"
+#include "_systems.hpp"
 
 namespace e2d
 {
-    class render_system final : public ecs::system {
+    class render_system final
+        : public ecs::system<ecs::after<systems::render_event>> {
     public:
         render_system();
-        ~render_system() noexcept final;
-        void process(ecs::registry& owner) override;
+        ~render_system() noexcept;
+
+        void process(
+            ecs::registry& owner,
+            const ecs::after<systems::render_event>& trigger) override;
     private:
         class internal_state;
         std::unique_ptr<internal_state> state_;
diff --git a/headers/enduro2d/high/systems/spine_system.hpp b/headers/enduro2d/high/systems/spine_system.hpp
new file mode 100644
index 00000000..d3c4fd4a
--- /dev/null
+++ b/headers/enduro2d/high/systems/spine_system.hpp
@@ -0,0 +1,26 @@
+/*******************************************************************************
+ * This file is part of the "Enduro2D"
+ * For conditions of distribution and use, see copyright notice in LICENSE.md
+ * Copyright (C) 2018-2019, by Matvey Cherevko (blackmatov@gmail.com)
+ ******************************************************************************/
+
+#pragma once
+
+#include "_systems.hpp"
+
+namespace e2d
+{
+    class spine_system final
+        : public ecs::system<ecs::after<systems::update_event>> {
+    public:
+        spine_system();
+        ~spine_system() noexcept;
+
+        void process(
+            ecs::registry& owner,
+            const ecs::after<systems::update_event>& trigger) override;
+    private:
+        class internal_state;
+        std::unique_ptr<internal_state> state_;
+    };
+}
diff --git a/headers/enduro2d/high/systems/spine_systems.hpp b/headers/enduro2d/high/systems/spine_systems.hpp
deleted file mode 100644
index c13844a8..00000000
--- a/headers/enduro2d/high/systems/spine_systems.hpp
+++ /dev/null
@@ -1,32 +0,0 @@
-/*******************************************************************************
- * This file is part of the "Enduro2D"
- * For conditions of distribution and use, see copyright notice in LICENSE.md
- * Copyright (C) 2018-2019, by Matvey Cherevko (blackmatov@gmail.com)
- ******************************************************************************/
-
-#pragma once
-
-#include "../_high.hpp"
-
-namespace e2d
-{
-    class spine_pre_system final : public ecs::system {
-    public:
-        spine_pre_system();
-        ~spine_pre_system() noexcept final;
-        void process(ecs::registry& owner) override;
-    private:
-        class internal_state;
-        std::unique_ptr<internal_state> state_;
-    };
-
-    class spine_post_system final : public ecs::system {
-    public:
-        spine_post_system();
-        ~spine_post_system() noexcept final;
-        void process(ecs::registry& owner) override;
-    private:
-        class internal_state;
-        std::unique_ptr<internal_state> state_;
-    };
-}
diff --git a/headers/enduro2d/high/world.hpp b/headers/enduro2d/high/world.hpp
index f894f740..928f335e 100644
--- a/headers/enduro2d/high/world.hpp
+++ b/headers/enduro2d/high/world.hpp
@@ -14,20 +14,6 @@
 namespace e2d
 {
     class world final : public module<world> {
-    public:
-        enum priorities : ecs::priority_t {
-            priority_update_section_begin = 0,
-                priority_pre_update = 500,
-                priority_update = 1000,
-                priority_post_update = 1500,
-            priority_update_section_end = 2000,
-
-            priority_render_section_begin = 2500,
-                priority_pre_render = 3000,
-                priority_render = 3500,
-                priority_post_render = 4000,
-            priority_render_section_end = 4500
-        };
     public:
         world() = default;
         ~world() noexcept final;
diff --git a/samples/sources/sample_03/sample_03.cpp b/samples/sources/sample_03/sample_03.cpp
index 77d68f29..66babb27 100644
--- a/samples/sources/sample_03/sample_03.cpp
+++ b/samples/sources/sample_03/sample_03.cpp
@@ -13,10 +13,13 @@ namespace
         v3f axis;
     };
 
-    class game_system final : public ecs::system {
+    class game_system final : public systems::update_system {
     public:
-        void process(ecs::registry& owner) override {
-            E2D_UNUSED(owner);
+        void process(
+            ecs::registry& owner,
+            const systems::update_event& event) override
+        {
+            E2D_UNUSED(owner, event);
             const keyboard& k = the<input>().keyboard();
 
             if ( k.is_key_just_released(keyboard_key::f12) ) {
@@ -33,9 +36,13 @@ namespace
         }
     };
 
-    class camera_system final : public ecs::system {
+    class camera_system final : public systems::render_system {
     public:
-        void process(ecs::registry& owner) override {
+        void process(
+            ecs::registry& owner,
+            const systems::render_event& event) override
+        {
+            E2D_UNUSED(event);
             owner.for_joined_components<camera>(
             [](const ecs::const_entity&, camera& cam){
                 if ( !cam.target() ) {
@@ -48,18 +55,20 @@ namespace
         }
     };
 
-    class rotator_system final : public ecs::system {
+    class rotator_system final : public systems::update_system {
     public:
-        void process(ecs::registry& owner) override {
-            const f32 time = the<engine>().time();
+        void process(
+            ecs::registry& owner,
+            const systems::update_event& event) override
+        {
             owner.for_joined_components<rotator, actor>(
-                [&time](const ecs::const_entity&, const rotator& rot, actor& act){
-                    const node_iptr node = act.node();
-                    if ( node ) {
-                        const q4f q = math::make_quat_from_axis_angle(make_rad(time), rot.axis);
-                        node->rotation(q);
-                    }
-                });
+            [&event](const ecs::const_entity&, const rotator& rot, actor& act){
+                const node_iptr node = act.node();
+                if ( node ) {
+                    const q4f q = math::make_quat_from_axis_angle(make_rad(event.time), rot.axis);
+                    node->rotation(q);
+                }
+            });
         }
     };
 
@@ -154,9 +163,10 @@ namespace
 
         bool create_systems() {
             ecs::registry_filler(the<world>().registry())
-                .system<game_system>(world::priority_update)
-                .system<rotator_system>(world::priority_update)
-                .system<camera_system>(world::priority_pre_render);
+            .feature<struct game_feature>(ecs::feature()
+                .add_system<game_system>()
+                .add_system<rotator_system>()
+                .add_system<camera_system>());
             return true;
         }
     };
diff --git a/samples/sources/sample_04/sample_04.cpp b/samples/sources/sample_04/sample_04.cpp
index 435f48ef..c334f89e 100644
--- a/samples/sources/sample_04/sample_04.cpp
+++ b/samples/sources/sample_04/sample_04.cpp
@@ -9,10 +9,13 @@ using namespace e2d;
 
 namespace
 {
-    class game_system final : public ecs::system {
+    class game_system final : public systems::update_system {
     public:
-        void process(ecs::registry& owner) override {
-            E2D_UNUSED(owner);
+        void process(
+            ecs::registry& owner,
+            const systems::update_event& event) override
+        {
+            E2D_UNUSED(owner, event);
             const keyboard& k = the<input>().keyboard();
 
             if ( k.is_key_just_released(keyboard_key::f12) ) {
@@ -29,9 +32,13 @@ namespace
         }
     };
 
-    class camera_system final : public ecs::system {
+    class camera_system final : public systems::render_system {
     public:
-        void process(ecs::registry& owner) override {
+        void process(
+            ecs::registry& owner,
+            const systems::render_event& event) override
+        {
+            E2D_UNUSED(event);
             owner.for_joined_components<camera>(
             [](const ecs::const_entity&, camera& cam){
                 if ( !cam.target() ) {
@@ -61,8 +68,9 @@ namespace
 
         bool create_systems() {
             ecs::registry_filler(the<world>().registry())
-                .system<game_system>(world::priority_update)
-                .system<camera_system>(world::priority_pre_render);
+            .feature<struct game_feature>(ecs::feature()
+                .add_system<game_system>()
+                .add_system<camera_system>());
             return true;
         }
     };
diff --git a/samples/sources/sample_06/sample_06.cpp b/samples/sources/sample_06/sample_06.cpp
index c8c64dfb..d0f1ac62 100644
--- a/samples/sources/sample_06/sample_06.cpp
+++ b/samples/sources/sample_06/sample_06.cpp
@@ -9,10 +9,13 @@ using namespace e2d;
 
 namespace
 {
-    class game_system final : public ecs::system {
+    class game_system final : public systems::update_system {
     public:
-        void process(ecs::registry& owner) override {
-            E2D_UNUSED(owner);
+        void process(
+            ecs::registry& owner,
+            const systems::update_event& event) override
+        {
+            E2D_UNUSED(owner, event);
             const keyboard& k = the<input>().keyboard();
 
             if ( k.is_key_just_released(keyboard_key::f12) ) {
@@ -68,9 +71,13 @@ namespace
         }
     };
 
-    class camera_system final : public ecs::system {
+    class camera_system final : public systems::render_system {
     public:
-        void process(ecs::registry& owner) override {
+        void process(
+            ecs::registry& owner,
+            const systems::render_event& event) override
+        {
+            E2D_UNUSED(event);
             owner.for_joined_components<camera>(
             [](const ecs::const_entity&, camera& cam){
                 if ( !cam.target() ) {
@@ -100,8 +107,9 @@ namespace
 
         bool create_systems() {
             ecs::registry_filler(the<world>().registry())
-                .system<game_system>(world::priority_update)
-                .system<camera_system>(world::priority_pre_render);
+            .feature<struct game_feature>(ecs::feature()
+                .add_system<game_system>()
+                .add_system<camera_system>());
             return true;
         }
     };
diff --git a/sources/enduro2d/core/render_impl/render_opengl_base.hpp b/sources/enduro2d/core/render_impl/render_opengl_base.hpp
index 0f42de90..be110117 100644
--- a/sources/enduro2d/core/render_impl/render_opengl_base.hpp
+++ b/sources/enduro2d/core/render_impl/render_opengl_base.hpp
@@ -12,7 +12,6 @@
 #if E2D_RENDER_MODE == E2D_RENDER_MODE_OPENGL || E2D_RENDER_MODE == E2D_RENDER_MODE_OPENGLES
 
 #if E2D_RENDER_MODE == E2D_RENDER_MODE_OPENGL
-#  define GLEW_STATIC
 #  include <GL/glew.h>
 #elif E2D_RENDER_MODE == E2D_RENDER_MODE_OPENGLES
 #  include <GLES2/gl2.h>
diff --git a/sources/enduro2d/high/starter.cpp b/sources/enduro2d/high/starter.cpp
index 8cc67463..0a153a04 100644
--- a/sources/enduro2d/high/starter.cpp
+++ b/sources/enduro2d/high/starter.cpp
@@ -25,7 +25,7 @@
 #include <enduro2d/high/systems/flipbook_system.hpp>
 #include <enduro2d/high/systems/label_system.hpp>
 #include <enduro2d/high/systems/render_system.hpp>
-#include <enduro2d/high/systems/spine_systems.hpp>
+#include <enduro2d/high/systems/spine_system.hpp>
 
 namespace
 {
@@ -45,11 +45,14 @@ namespace
 
         bool initialize() final {
             ecs::registry_filler(the<world>().registry())
-                .system<flipbook_system>(world::priority_pre_update)
-                .system<label_system>(world::priority_pre_update)
-                .system<spine_pre_system>(world::priority_pre_update)
-                .system<spine_post_system>(world::priority_post_update)
-                .system<render_system>(world::priority_render);
+                .feature<struct flipbook_feature>(ecs::feature()
+                    .add_system<flipbook_system>())
+                .feature<struct label_feature>(ecs::feature()
+                    .add_system<label_system>())
+                .feature<struct spine_feature>(ecs::feature()
+                    .add_system<spine_system>())
+                .feature<struct render_feature>(ecs::feature()
+                    .add_system<render_system>());
             return !application_ || application_->initialize();
         }
 
@@ -60,17 +63,24 @@ namespace
         }
 
         bool frame_tick() final {
-            the<world>().registry().process_systems_in_range(
-                world::priority_update_section_begin,
-                world::priority_update_section_end);
+            engine& e = the<engine>();
+            const f32 dt = e.delta_time();
+            const f32 time = e.time();
+
+            ecs::registry& registry = the<world>().registry();
+            registry.process_event(systems::pre_update_event{dt,time});
+            registry.process_event(systems::update_event{dt,time});
+            registry.process_event(systems::post_update_event{dt,time});
+
             return !the<window>().should_close()
                 || (application_ && !application_->on_should_close());
         }
 
         void frame_render() final {
-            the<world>().registry().process_systems_in_range(
-                world::priority_render_section_begin,
-                world::priority_render_section_end);
+            ecs::registry& registry = the<world>().registry();
+            registry.process_event(systems::pre_render_event{});
+            registry.process_event(systems::render_event{});
+            registry.process_event(systems::post_render_event{});
         }
     private:
         starter::application_uptr application_;
diff --git a/sources/enduro2d/high/systems/flipbook_system.cpp b/sources/enduro2d/high/systems/flipbook_system.cpp
index 5877ec3c..b1aa8067 100644
--- a/sources/enduro2d/high/systems/flipbook_system.cpp
+++ b/sources/enduro2d/high/systems/flipbook_system.cpp
@@ -82,8 +82,8 @@ namespace e2d
         internal_state() = default;
         ~internal_state() noexcept = default;
 
-        void process(ecs::registry& owner) {
-            update_flipbook_timers(the<engine>().delta_time(), owner);
+        void process(f32 dt, ecs::registry& owner) {
+            update_flipbook_timers(dt, owner);
             update_flipbook_sprites(owner);
         }
     };
@@ -96,7 +96,10 @@ namespace e2d
     : state_(new internal_state()) {}
     flipbook_system::~flipbook_system() noexcept = default;
 
-    void flipbook_system::process(ecs::registry& owner) {
-        state_->process(owner);
+    void flipbook_system::process(
+        ecs::registry& owner,
+        const ecs::after<systems::update_event>& trigger)
+    {
+        state_->process(trigger.event.dt, owner);
     }
 }
diff --git a/sources/enduro2d/high/systems/label_system.cpp b/sources/enduro2d/high/systems/label_system.cpp
index 2be21be9..c3dceaa2 100644
--- a/sources/enduro2d/high/systems/label_system.cpp
+++ b/sources/enduro2d/high/systems/label_system.cpp
@@ -382,7 +382,11 @@ namespace e2d
     : state_(new internal_state()) {}
     label_system::~label_system() noexcept = default;
 
-    void label_system::process(ecs::registry& owner) {
+    void label_system::process(
+        ecs::registry& owner,
+        const ecs::after<systems::update_event>& trigger)
+    {
+        E2D_UNUSED(trigger);
         state_->process(owner);
     }
 }
diff --git a/sources/enduro2d/high/systems/render_system.cpp b/sources/enduro2d/high/systems/render_system.cpp
index 9be52781..b6c313ee 100644
--- a/sources/enduro2d/high/systems/render_system.cpp
+++ b/sources/enduro2d/high/systems/render_system.cpp
@@ -117,7 +117,11 @@ namespace e2d
     : state_(new internal_state()) {}
     render_system::~render_system() noexcept = default;
 
-    void render_system::process(ecs::registry& owner) {
+    void render_system::process(
+        ecs::registry& owner,
+        const ecs::after<systems::render_event>& trigger)
+    {
+        E2D_UNUSED(trigger);
         state_->process(owner);
     }
 }
diff --git a/sources/enduro2d/high/systems/spine_pre_system.cpp b/sources/enduro2d/high/systems/spine_pre_system.cpp
deleted file mode 100644
index 16c26d0e..00000000
--- a/sources/enduro2d/high/systems/spine_pre_system.cpp
+++ /dev/null
@@ -1,62 +0,0 @@
-/*******************************************************************************
- * This file is part of the "Enduro2D"
- * For conditions of distribution and use, see copyright notice in LICENSE.md
- * Copyright (C) 2018-2019, by Matvey Cherevko (blackmatov@gmail.com)
- ******************************************************************************/
-
-#include <enduro2d/high/systems/spine_systems.hpp>
-
-#include <enduro2d/high/components/spine_player.hpp>
-#include <enduro2d/high/components/spine_player_cmd.hpp>
-#include <enduro2d/high/components/spine_player_evt.hpp>
-
-#include <spine/spine.h>
-
-namespace e2d
-{
-    //
-    // internal_state
-    //
-
-    class spine_pre_system::internal_state final {
-    public:
-        internal_state() = default;
-        ~internal_state() noexcept = default;
-
-        void process(ecs::registry& owner) {
-            update_animations(owner);
-        }
-    private:
-        void update_animations(ecs::registry& owner) {
-            const float dt = the<engine>().delta_time();
-            owner.for_each_component<spine_player>([dt](
-                const ecs::const_entity&,
-                spine_player& p)
-            {
-                spSkeleton* skeleton = p.skeleton().get();
-                spAnimationState* anim_state = p.animation().get();
-
-                if ( !skeleton || !anim_state ) {
-                    return;
-                }
-
-                spSkeleton_update(skeleton, dt);
-                spAnimationState_update(anim_state, dt);
-                spAnimationState_apply(anim_state, skeleton);
-                spSkeleton_updateWorldTransform(skeleton);
-            });
-        }
-    };
-
-    //
-    // spine_pre_system
-    //
-
-    spine_pre_system::spine_pre_system()
-    : state_(new internal_state()) {}
-    spine_pre_system::~spine_pre_system() noexcept = default;
-
-    void spine_pre_system::process(ecs::registry& owner) {
-        state_->process(owner);
-    }
-}
diff --git a/sources/enduro2d/high/systems/spine_post_system.cpp b/sources/enduro2d/high/systems/spine_system.cpp
similarity index 75%
rename from sources/enduro2d/high/systems/spine_post_system.cpp
rename to sources/enduro2d/high/systems/spine_system.cpp
index d6f754ab..0f14bdab 100644
--- a/sources/enduro2d/high/systems/spine_post_system.cpp
+++ b/sources/enduro2d/high/systems/spine_system.cpp
@@ -4,7 +4,7 @@
  * Copyright (C) 2018-2019, by Matvey Cherevko (blackmatov@gmail.com)
  ******************************************************************************/
 
-#include <enduro2d/high/systems/spine_systems.hpp>
+#include <enduro2d/high/systems/spine_system.hpp>
 
 #include <enduro2d/high/components/spine_player.hpp>
 #include <enduro2d/high/components/spine_player_cmd.hpp>
@@ -166,6 +166,59 @@ namespace
         spSkeletonData& skeleton_data_;
         spAnimationState& animation_state_;
     };
+
+    void clear_events(ecs::registry& owner) {
+        owner.for_each_component<spine_player_evt>([
+        ](const ecs::const_entity&, spine_player_evt& pe) {
+            pe.clear_events();
+        });
+    }
+
+    void update_animations(f32 dt, ecs::registry& owner) {
+        owner.for_each_component<spine_player>([dt](
+            const ecs::const_entity&,
+            spine_player& p)
+        {
+            spSkeleton* skeleton = p.skeleton().get();
+            spAnimationState* anim_state = p.animation().get();
+
+            if ( !skeleton || !anim_state ) {
+                return;
+            }
+
+            spSkeleton_update(skeleton, dt);
+            spAnimationState_update(anim_state, dt);
+            spAnimationState_apply(anim_state, skeleton);
+            spSkeleton_updateWorldTransform(skeleton);
+        });
+    }
+
+    void process_commands(ecs::registry& owner) {
+        owner.for_joined_components<spine_player_cmd, spine_player>([](
+            ecs::entity e,
+            const spine_player_cmd& pc,
+            spine_player& p)
+        {
+            spSkeleton* skeleton = p.skeleton().get();
+            spAnimationState* animation_state = p.animation().get();
+
+            if ( !skeleton || !skeleton->data || !animation_state ) {
+                return;
+            }
+
+            command_visitor v(e, *skeleton->data, *animation_state);
+            for ( const auto& cmd : pc.commands() ) {
+                std::visit(v, cmd);
+            }
+        });
+    }
+
+    void clear_commands(ecs::registry& owner) {
+        owner.for_each_component<spine_player_cmd>([
+        ](const ecs::const_entity&, spine_player_cmd& pc) {
+            pc.clear_commands();
+        });
+    }
 }
 
 namespace e2d
@@ -174,64 +227,34 @@ namespace e2d
     // internal_state
     //
 
-    class spine_post_system::internal_state final {
+    class spine_system::internal_state final {
     public:
         internal_state() = default;
         ~internal_state() noexcept = default;
 
-        void process(ecs::registry& owner) {
+        void process(f32 dt, ecs::registry& owner) {
             process_commands(owner);
             clear_commands(owner);
             clear_events(owner);
-        }
-    private:
-        void process_commands(ecs::registry& owner) {
-            owner.for_joined_components<spine_player_cmd, spine_player>([](
-                ecs::entity e,
-                const spine_player_cmd& pc,
-                spine_player& p)
-            {
-                spSkeleton* skeleton = p.skeleton().get();
-                spAnimationState* animation_state = p.animation().get();
-
-                if ( !skeleton || !skeleton->data || !animation_state ) {
-                    return;
-                }
-
-                command_visitor v(e, *skeleton->data, *animation_state);
-                for ( const auto& cmd : pc.commands() ) {
-                    std::visit(v, cmd);
-                }
-            });
-        }
-
-        void clear_commands(ecs::registry& owner) {
-            owner.for_each_component<spine_player_cmd>([
-            ](const ecs::const_entity&, spine_player_cmd& pc) {
-                pc.clear_commands();
-            });
-        }
-
-        void clear_events(ecs::registry& owner) {
-            owner.for_each_component<spine_player_evt>([
-            ](const ecs::const_entity&, spine_player_evt& pe) {
-                pe.clear_events();
-            });
+            update_animations(dt, owner);
         }
     };
 
     //
-    // spine_post_system
+    // spine_system
     //
 
-    spine_post_system::spine_post_system()
+    spine_system::spine_system()
     : state_(new internal_state()) {}
 
-    spine_post_system::~spine_post_system() noexcept {
+    spine_system::~spine_system() noexcept {
         spAnimationState_disposeStatics();
     }
 
-    void spine_post_system::process(ecs::registry& owner) {
-        state_->process(owner);
+    void spine_system::process(
+        ecs::registry& owner,
+        const ecs::after<systems::update_event>& trigger)
+    {
+        state_->process(trigger.event.dt, owner);
     }
 }