Don't use getDistance from battle graph for kart

As sometimes it will return 0 if kart is on unknown node

Also try to make banana avoidance better

src/karts/controller/ai_base_controller.cpp

@@ -310,6 +310,6 @@ void AIBaseController::checkPosition(const Vec3 &point, posData *pos_data,
 
     pos_data->angle = atan2(fabsf(local_coordinates.getX()),
         fabsf(local_coordinates.getZ()));
-    pos_data->distance = p.length_2d();
+    pos_data->distance = p.length();
 
 }   //  checkPosition

src/karts/controller/arena_ai.cpp

@@ -61,6 +61,7 @@ void ArenaAI::reset()
     m_cur_kart_pos_data = {0};
     m_is_stuck = false;
     m_is_uturn = false;
+    m_avoiding_banana = false;
     m_target_point = Vec3(0, 0, 0);
     m_time_since_last_shot = 0.0f;
     m_time_since_driving = 0.0f;
@@ -86,6 +87,7 @@ void ArenaAI::update(float dt)
     // This is used to enable firing an item backwards.
     m_controls->m_look_back = false;
     m_controls->m_nitro     = false;
+    m_avoiding_banana = false;
 
     // Don't do anything if there is currently a kart animations shown.
     if (m_kart->getKartAnimation())
@@ -380,23 +382,22 @@ void ArenaAI::updateBananaLocation()
         if (it != item_list.end())
         {
             Vec3 banana_lc;
-            posData banana_pos = {0};
-            checkPosition(it->first->getXYZ(), &banana_pos, &banana_lc,
+            checkPosition(it->first->getXYZ(), NULL, &banana_lc,
                 true/*use_front_xyz*/);
 
-            // If satisfy the below condition, AI should not eat banana
-            if (banana_pos.behind || banana_pos.angle > 0.3f)
+            // If satisfy the below condition, AI should not eat banana:
+            // banana_lc.z() < 0.0f, behind the kart
+            if (banana_lc.z() < 0.0f)
             {
                 node++;
                 continue;
             }
 
-            const float dist = banana_lc.length() * 2;
-            banana_lc = (banana_lc.x() < 0 ? banana_lc + Vec3(dist, 0, 0) :
-                        banana_lc - Vec3(dist, 0, 0));
             // If the node AI will pass has a banana, adjust the aim position
+            banana_lc = (banana_lc.x() < 0 ? banana_lc + Vec3(5, 0, 0) :
+                        banana_lc - Vec3(5, 0, 0));
             m_aiming_points[1] = m_kart->getTrans()(banana_lc);
-
+            m_avoiding_banana = true;
             // Handle one banana only
             return;
         }

src/karts/controller/arena_ai.hpp

@@ -64,6 +64,8 @@ protected:
     /** The target point. */
     Vec3 m_target_point;
 
+    bool m_avoiding_banana;
+
     void  collectItemInArena(Vec3*, int*) const;
     float findAngleFrom3Edges(float a, float b, float c);
 private:
@@ -122,7 +124,7 @@ private:
     virtual void resetAfterStop() {};
     virtual void findClosestKart(bool use_difficulty) = 0;
     virtual void findTarget() = 0;
-    virtual bool forceBraking() { return false; }
+    virtual bool forceBraking() { return m_avoiding_banana; }
     virtual bool ignorePathFinding() { return false; }
 public:
     static int   m_test_node_for_banana;

src/karts/controller/battle_ai.cpp

@@ -25,7 +25,6 @@
 #include "karts/abstract_kart.hpp"
 #include "karts/controller/kart_control.hpp"
 #include "modes/three_strikes_battle.hpp"
-#include "tracks/battle_graph.hpp"
 
 #ifdef AI_DEBUG
 #include "irrlicht.h"
@@ -119,11 +118,10 @@ void BattleAI::findClosestKart(bool use_difficulty)
                 continue;
         }
 
-        float test_distance = BattleGraph::get()->getDistance(m_world
-            ->getKartNode(kart->getWorldKartId()), getCurrentNode());
-        if (test_distance <= distance)
+        Vec3 d = kart->getXYZ() - m_kart->getXYZ();
+        if (d.length() <= distance)
         {
-            distance = test_distance;
+            distance = d.length();
             closest_kart_num = i;
         }
     }
@@ -136,7 +134,6 @@ void BattleAI::findClosestKart(bool use_difficulty)
     {
         m_closest_kart = m_world->getKart(closest_kart_num);
         checkPosition(m_closest_kart_point, &m_closest_kart_pos_data);
-        m_closest_kart_pos_data.distance = distance;
 
         // Do a mini-skid to closest kart only when firing target,
         // not straight ahead, not too far, in front of it

src/karts/controller/soccer_ai.hpp

@@ -66,7 +66,8 @@ private:
     virtual int  getCurrentNode() const;
     virtual bool isWaiting() const;
     virtual bool canSkid(float steer_fraction)           { return false; }
-    virtual bool forceBraking() OVERRIDE         { return m_force_brake; }
+    virtual bool forceBraking() OVERRIDE
+                            { return m_avoiding_banana || m_force_brake; }
     virtual bool ignorePathFinding() OVERRIDE
                                                 { return m_chasing_ball; }
 public: