Fixed disappearing rubber ball on steep slopes (like the ramp

in sand track).


git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/trunk@9555 178a84e3-b1eb-0310-8ba1-8eac791a3b58

src/items/flyable.cpp

@@ -130,6 +130,7 @@ Flyable::Flyable(Kart *kart, PowerupManager::PowerupType type, float mass)
     m_mass                         = mass;
     m_adjust_up_velocity           = true;
     m_time_since_thrown            = 0;
+    m_position_offset              = Vec3(0,0,0);
     m_owner_has_temporary_immunity = true;
     m_max_lifespan = -1;
 
@@ -397,7 +398,10 @@ void Flyable::update(float dt)
         return;
     }
 
-    TerrainInfo::update(xyz);
+    // Add the position offset so that the flyable can adjust its position 
+    // (usually to do the raycast from a slightly higher position to avoid
+    // problems finding the terrain in steep uphill sections).
+    TerrainInfo::update(xyz+m_position_offset);
 
     if(m_adjust_up_velocity)
     {

src/items/flyable.hpp

@@ -51,11 +51,18 @@ private:
      *  It can happen that more than one collision between a rocket and
      *  a track or kart is reported by the physics.                        */
     bool              m_exploded;
+
     /** If this flag is set, the up velocity of the kart will not be
      *  adjusted in case that the objects is too high or too low above the
      *  terrain. Otherwise gravity will not work correctly on this object. */
     bool              m_adjust_up_velocity;
 
+    /** An offset that is added when doing the raycast for terrain. This
+     *  is useful in case that the position of the object is just under
+     *  the terrain (perhaps due to floating point errors), and would 
+     *  otherwise result in an invalid terrain. */
+    Vec3              m_position_offset;
+
 protected:
     /** Kart which shot this flyable. */
     Kart*             m_owner;
@@ -144,27 +151,50 @@ public:
                  Flyable     (Kart* kart, PowerupManager::PowerupType type, 
                               float mass=1.0f);
     virtual     ~Flyable     ();
-    /** Enables/disables adjusting ov velocity depending on height above
-     *  terrain. Missiles can 'follow the terrain' with this adjustment,
-     *  but gravity will basically be disabled.                          */
-    void         setAdjustUpVelocity(bool f) { m_adjust_up_velocity = f; }
     static void  init        (const XMLNode &node, scene::IMesh *model,
                               PowerupManager::PowerupType type);
     virtual void update      (float);
     void         updateFromServer(const FlyableInfo &f, float dt);
+    bool         isOwnerImmunity(const Kart *kart_hit) const;
 
+    // ------------------------------------------------------------------------
+    /** If true the up velocity of the flyable will be adjust so that the 
+     *  flyable stays at a height close to the average height.
+     *  \param f True if the up velocity should be adjusted. */
+    void         setAdjustUpVelocity(bool f) { m_adjust_up_velocity = f; }
+    // ------------------------------------------------------------------------
+    /** Sets the offset to be used when determining the terrain under the
+     *  flyable. This needs to be used in case that an object might be just
+     *  under the actual terrain (e.g. rubber ball on a steep uphill slope). */
+    void         setPositionOffset(const Vec3 &o) {m_position_offset = o; }
+    // ------------------------------------------------------------------------
+    /** Called when this flyable hits the track. */
     virtual void hitTrack    () {};
+    // ------------------------------------------------------------------------
+    /** Called when this flyable hit a kart or physical object. 
+     *  \param kart Pointer to the kart hit (NULL if no kart was hit).
+     *  \param obj  Pointer to the object hit (NULL if no object was hit). */
     virtual void hit         (Kart* kart, PhysicalObject* obj=NULL);
+    // ------------------------------------------------------------------------
+    /** Enables/disables adjusting ov velocity depending on height above
+     *  terrain. Missiles can 'follow the terrain' with this adjustment,
+     *  but gravity will basically be disabled.                          */
     bool         hasHit      () { return m_has_hit_something; }
+    // ------------------------------------------------------------------------
     /** Indicates that something was hit and that this object must
      *  be removed. */
     void         setHasHit   () { m_has_hit_something = true; }
+    // ------------------------------------------------------------------------
+    /** Resets this flyable. */
     void         reset       () { Moveable::reset();          }
-    bool         isOwnerImmunity(const Kart *kart_hit) const;
+    // ------------------------------------------------------------------------
     /** Returns the type of flyable. */
     PowerupManager::PowerupType
                   getType() const {return m_type;}
+    // ------------------------------------------------------------------------
+    /** Returns the sfx that should be played in case of an explosion. */
     virtual const char*  getExplosionSound() const { return "explosion"; }
+    // ------------------------------------------------------------------------
     /** Indicates if an explosion needs to be added if this flyable
       * is removed. */
     virtual bool needsExplosion() const {return true;}

src/items/rubber_ball.cpp

@@ -34,6 +34,10 @@ RubberBall::RubberBall(Kart *kart)
           : Flyable(kart, PowerupManager::POWERUP_RUBBERBALL, 0.0f /* mass */),
             TrackSector()
 {
+    // The rubber ball often misses the terrain on steep uphill slopes, e.g.
+    // the ramp in sand track. Add an Y offset so that the terrain raycast
+    // will always be done from a position high enough to avoid this.
+    setPositionOffset(Vec3(0, 1.0f, 0));
     float forw_offset = 0.5f*kart->getKartLength() + m_extend.getZ()*0.5f+5.0f;
     
     createPhysics(forw_offset, btVector3(0.0f, 0.0f, m_speed*2),