diff --git a/server/gameserver/android.ai.cc b/server/gameserver/android.ai.cc
index 95157ea..0d3b38c 100644
--- a/server/gameserver/android.ai.cc
+++ b/server/gameserver/android.ai.cc
@@ -61,9 +61,8 @@ void AndroidAI::ChangeToState(AndroidState_e to_state)
     case AS_moving:
         {
             Human* hum = (Human*)owner;
-            float angle = ((float)rand() / RAND_MAX) * 2.0f;
             hum->move_dir = Vector2D(1.0f, 0);
-            hum->move_dir = hum->move_dir.Rotate(angle);
+            hum->move_dir.Rotate(a8::RandAngle());
             hum->move_dir.Normalize();
             hum->attack_dir = hum->move_dir;
         }
diff --git a/server/gameserver/app.cc b/server/gameserver/app.cc
index 7371fc3..c17bfe9 100755
--- a/server/gameserver/app.cc
+++ b/server/gameserver/app.cc
@@ -63,7 +63,7 @@ void App::Init(int argc, char* argv[])
     #if 0
     {
         Vector2D v1(1, 1);
-        Vector2D v2 = v1.Rotate(-0.25);
+        v1.Rotate(-0.25);
         TestGlm();
         int i = 0;
     }
diff --git a/server/gameserver/human.cc b/server/gameserver/human.cc
index 975cc74..9dd933a 100644
--- a/server/gameserver/human.cc
+++ b/server/gameserver/human.cc
@@ -222,3 +222,8 @@ void Human::FindPath()
         }
     }
 }
+
+float Human::GetRadius()
+{
+    return meta->i->radius();
+}
diff --git a/server/gameserver/human.h b/server/gameserver/human.h
index 22232d5..e59ce68 100644
--- a/server/gameserver/human.h
+++ b/server/gameserver/human.h
@@ -60,6 +60,7 @@ class Human : public Entity
     void RecalcSelfCollider();
     bool IsCollision();
     void FindPath();
+    float GetRadius();
 
 private:
     CircleCollider* self_collider_ = nullptr;
diff --git a/server/gameserver/movement.cc b/server/gameserver/movement.cc
index 6fd47c2..f9797ce 100644
--- a/server/gameserver/movement.cc
+++ b/server/gameserver/movement.cc
@@ -11,12 +11,17 @@ void MovementComponent::Update(int delta_time)
             ++path_index_;
             return;
         }
-        Vector2D path = target_point.pos - owner->pos;
+        #if 1
+        assert(false);
+        #else
+        Vector2D dir = target_point.pos - owner->pos;
+        dir.Normalize();
         float distance = path.Norm();
-        owner->pos = owner->pos + path.Normalize() * std::min(move_speed_, distance);
+        owner->pos = owner->pos + dir * std::min(move_speed_, distance);
         if (owner->pos == target_point.pos) {
             ++path_index_;
         }
+        #endif
     }
 }
 
diff --git a/server/gameserver/room.cc b/server/gameserver/room.cc
index 67c4037..5168952 100644
--- a/server/gameserver/room.cc
+++ b/server/gameserver/room.cc
@@ -72,8 +72,7 @@ void Room::AddPlayer(Player* hum)
         hum->pos.y = 2000 + rand() % 200;
         hum->attack_dir = hum->pos;
         hum->attack_dir.Normalize();
-        float angle = ((float)rand() / RAND_MAX) * 2.0f;
-        hum->attack_dir.Rotate(angle);
+        hum->attack_dir.Rotate(a8::RandAngle());
     }
     hum->room = this;
     uniid_hash_[hum->entity_uniid] = hum;
@@ -118,8 +117,7 @@ void Room::ShuaAndroid()
             hum->pos.y = 200 + rand() % 500;
             hum->attack_dir = hum->pos;
             hum->attack_dir.Normalize();
-            float angle = ((float)rand() / RAND_MAX) * 2.0f;
-            hum->attack_dir.Rotate(angle);
+            hum->attack_dir.Rotate(a8::RandAngle());
         }
         hum->room = this;
         hum->Initialize();
@@ -147,6 +145,12 @@ void Room::ShuaObstacle(Human* hum)
         entity->room = this;
         entity->meta = thing;
         entity->entity_uniid = AllocUniid();
+        #if 1
+        {
+            Vector2D dir = hum->pos;
+            dir.Normalize();
+        }
+        #endif
         entity->Initialize();
         uniid_hash_[entity->entity_uniid] = entity;
         for (auto& pair : human_hash_) {
@@ -158,10 +162,12 @@ void Room::ShuaObstacle(Human* hum)
 
 bool Room::RandomPos(Human* hum, float distance, Vector2D& out_pos)
 {
-    float angle = ((float)rand() / RAND_MAX) * 2.0f;
+    Vector2D dir = hum->pos;
+    dir.Rotate(a8::RandAngle());
+    dir.Normalize();
     CircleCollider collider;
     collider.owner = hum;
-    collider.pos = hum->pos.Rotate(angle).Normalize() * distance;
+    collider.pos = dir * distance;
     collider.rad = hum->meta->i->radius();
 
     for (auto& pair : uniid_hash_) {
diff --git a/server/gameserver/types.cc b/server/gameserver/types.cc
index 4447003..f51b1cf 100644
--- a/server/gameserver/types.cc
+++ b/server/gameserver/types.cc
@@ -28,7 +28,7 @@ void Vector2D::FromPB(const cs::MFVector2D* pb_obj)
     y = pb_obj->y();
 }
 
-Vector2D& Vector2D::Normalize()
+void Vector2D::Normalize()
 {
     #if 1
     glm::vec2 v = glm::normalize(glm::vec2(x, y));
@@ -40,7 +40,6 @@ Vector2D& Vector2D::Normalize()
     x = v[0];
     y = v[1];
     #endif
-    return *this;
 }
 
 bool Vector2D::operator == (const Vector2D& b) const
@@ -97,11 +96,12 @@ Vector2D Vector2D::operator / (float scale) const
 #include <Eigen/Dense>
 #endif
 
-Vector2D Vector2D::Rotate(float angle)
+void Vector2D::Rotate(float angle)
 {
     Eigen::Vector3f v(x, y, 0);
     v = Eigen::AngleAxisf(angle * 3.1415926f, Eigen::Vector3f::UnitZ()) * v;
-    return Vector2D(v[0], v[1]);
+    x = v[0];
+    y = v[1];
 }
 
 Vector2D Vector2D::Perp()
@@ -213,4 +213,3 @@ static Polygon newPolygon(std::vector<Vector2D>& vertices)
     return shape;
 }
 #endif
-
diff --git a/server/gameserver/types.h b/server/gameserver/types.h
index aa115d9..9c7367c 100755
--- a/server/gameserver/types.h
+++ b/server/gameserver/types.h
@@ -23,14 +23,14 @@ struct Vector2D
 
     void ToPB(cs::MFVector2D* pb_obj);
     void FromPB(const cs::MFVector2D* pb_obj);
-    Vector2D& Normalize();
+    void Normalize();
+    void Rotate(float angle);
 
     bool operator == (const Vector2D& b) const;
     Vector2D operator + (const Vector2D& b) const;
     Vector2D operator - (const Vector2D& b) const;
     Vector2D operator * (float scale) const;
     Vector2D operator / (float scale) const;
-    Vector2D Rotate(float angle);
     Vector2D Perp();
     float Dot(const Vector2D& v) const;
     float Norm();
diff --git a/third_party/a8engine b/third_party/a8engine
index e7ff93f..923b076 160000
--- a/third_party/a8engine
+++ b/third_party/a8engine
@@ -1 +1 @@
-Subproject commit e7ff93f844ce7b7356f6d743be27618d7539c885
+Subproject commit 923b076d57a0ee4bdf0e15624e7f4595c8b2fb42