From 7a28ddace2596da57b6ba3d431466b293111700d Mon Sep 17 00:00:00 2001
From: Nomango <569629550@qq.com>
Date: Tue, 29 May 2018 22:12:01 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8DMoveBy=E5=8A=A8=E4=BD=9C?=
 =?UTF-8?q?=E7=9A=84=E9=97=AE=E9=A2=98?=
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---
 core/Action/MoveBy.cpp | 11 +++++++++--
 core/e2daction.h       |  1 +
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/core/Action/MoveBy.cpp b/core/Action/MoveBy.cpp
index e4da97a6..5d14588d 100644
--- a/core/Action/MoveBy.cpp
+++ b/core/Action/MoveBy.cpp
@@ -14,7 +14,7 @@ void e2d::MoveBy::_init()
 
 	if (_target)
 	{
-		_startPos = _target->getPos();
+		_prevPos = _startPos = _target->getPos();
 	}
 }
 
@@ -24,7 +24,14 @@ void e2d::MoveBy::_update()
 
 	if (_target)
 	{
-		_target->setPos(_startPos + _deltaPos * _delta);
+		Point currentPos = _target->getPos();
+		Vector diff = currentPos - _prevPos;
+		_startPos = _startPos + diff;
+
+		Point newPos = _startPos + (_deltaPos * _delta);
+		_target->setPos(newPos);
+
+		_prevPos = newPos;
 	}
 }
 
diff --git a/core/e2daction.h b/core/e2daction.h
index de88ffb3..8b4bd63c 100644
--- a/core/e2daction.h
+++ b/core/e2daction.h
@@ -144,6 +144,7 @@ protected:
 
 protected:
 	Point	_startPos;
+	Point	_prevPos;
 	Vector	_deltaPos;
 };