From f48491c2790ab94cbe11616c58c69669621a1739 Mon Sep 17 00:00:00 2001
From: Benau <Benau@users.noreply.github.com>
Date: Mon, 20 Aug 2018 15:40:29 +0800
Subject: [PATCH] Make sure all karts has the same position before go phase

---
 src/karts/abstract_kart.cpp | 34 ++++++++++++++++++++++++----------
 src/karts/abstract_kart.hpp |  5 ++++-
 src/karts/ghost_kart.hpp    |  4 ++--
 src/modes/world.cpp         |  2 ++
 4 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/src/karts/abstract_kart.cpp b/src/karts/abstract_kart.cpp
index f5ed4e05b..d6fda8d50 100644
--- a/src/karts/abstract_kart.cpp
+++ b/src/karts/abstract_kart.cpp
@@ -143,16 +143,6 @@ void AbstractKart::setKartAnimation(AbstractKartAnimation *ka)
     m_kart_animation = ka;
 }   // setKartAnimation
 
-// ----------------------------------------------------------------------------
-/** Moves the current physical transform into this kart's position.
- */
-void AbstractKart::kartIsInRestNow()
-{
-    // Update the kart transforms with the newly computed position
-    // after all karts are reset
-    setTrans(getBody()->getWorldTransform());
-}   // kartIsInRest
-
 // ----------------------------------------------------------------------------
 /** Returns the time at which the kart was at a given distance.
  * Returns -1.0f if none */
@@ -160,3 +150,27 @@ float AbstractKart::getTimeForDistance(float distance)
 {
     return -1.0f;
 }   // getTimeForDistance
+
+// ----------------------------------------------------------------------------
+/** Moves the current physical transform into this kart's position.
+ */
+void AbstractKart::kartIsInRestNow()
+{
+    // Update the kart transforms with the newly computed position
+    // after all karts are reset
+    m_starting_transform = getBody()->getWorldTransform();
+    setTrans(m_starting_transform);
+}   // kartIsInRest
+
+// ------------------------------------------------------------------------
+/** Called before go phase to make sure all karts start at the same
+ *  position in case there is a slope. */
+void AbstractKart::makeKartRest()
+{
+    btRigidBody *body = getBody();
+    body->clearForces();
+    body->setLinearVelocity(Vec3(0.0f));
+    body->setAngularVelocity(Vec3(0.0f));
+    body->proceedToTransform(m_starting_transform);
+    setTrans(m_starting_transform);
+}   // makeKartRest
diff --git a/src/karts/abstract_kart.hpp b/src/karts/abstract_kart.hpp
index be51191b1..95c479a01 100644
--- a/src/karts/abstract_kart.hpp
+++ b/src/karts/abstract_kart.hpp
@@ -74,7 +74,7 @@ private:
     /** Index of kart in world. */
     unsigned int m_world_kart_id;
 
-
+    btTransform m_starting_transform;
 protected:
     /** The kart properties. */
     std::unique_ptr<KartProperties> m_kart_properties;
@@ -509,6 +509,9 @@ public:
     virtual void playSound(SFXBuffer* buffer) = 0;
     // ------------------------------------------------------------------------
     virtual bool isVisible() = 0;
+    // ------------------------------------------------------------------------
+    virtual void makeKartRest();
+
 };   // AbstractKart
 
 
diff --git a/src/karts/ghost_kart.hpp b/src/karts/ghost_kart.hpp
index 47fe0b98e..f91d79287 100644
--- a/src/karts/ghost_kart.hpp
+++ b/src/karts/ghost_kart.hpp
@@ -98,9 +98,9 @@ public:
     float getTimeForEggs(int egg_number);
 
     // ------------------------------------------------------------------------
-    virtual void  kartIsInRestNow() OVERRIDE {};
+    virtual void kartIsInRestNow() OVERRIDE {}
     // ------------------------------------------------------------------------
-    
+    virtual void makeKartRest() OVERRIDE {}
 };   // GhostKart
 #endif
 
diff --git a/src/modes/world.cpp b/src/modes/world.cpp
index 06a1ad67e..c5a8c53bc 100644
--- a/src/modes/world.cpp
+++ b/src/modes/world.cpp
@@ -1064,6 +1064,8 @@ void World::update(int ticks)
         // Update all karts that are not eliminated
         if(!m_karts[i]->isEliminated() || (sta && sta->isMoving()))
             m_karts[i]->update(ticks);
+        if (isStartPhase())
+            m_karts[i]->makeKartRest();
     }
     PROFILER_POP_CPU_MARKER();
     if(race_manager->isRecordingRace()) ReplayRecorder::get()->update(ticks);