1) Added new physics properties to kart_properties

to tune kart stability.
2) Made the kart accessible in btKart (so that the physics
   can access the kart properties directly).
3) Removed unused tuning variable in constructor of btKart.
4) Removed jumping related code.


git-svn-id: svn+ssh://svn.code.sf.net/p/supertuxkart/code/main/branches/physics@10147 178a84e3-b1eb-0310-8ba1-8eac791a3b58

data/stk_config.xml

@@ -44,7 +44,7 @@
   <news max-display="10"/>
 
   <!-- If the normals (for wheel raycasts) should be smoothened -->
-  <physics smooth-normals="false"/>
+  <physics smooth-normals="true"/>
 
   <!-- The title music. -->
   <music title="main_theme.music"/>
@@ -231,9 +231,12 @@
     <mass value="225"/>
 
     <!-- Suspension related values. stiffness: kart's suspension stiffness.
-         rest Length of suspension when at rest. travel-cm: maximum 
+         rest: Length of suspension when at rest. 
-         movement of suspension - in cm!!  -->
+         travel-cm: maximum movement of suspension - in cm!! 
-    <suspension stiffness="248.0" rest="0.2" travel-cm="19"/>
+         exp-string-response: dampen the suspension spring reaction 
+            exponentially  -->
+    <suspension stiffness="50" rest="0.2" travel-cm="19"
+         exp-spring-response="true"/>
 
     <!-- Wheel related parameters: damping-relaxation/compression: for
          bullet, damping parameters. Radius and width of wheel.
@@ -241,7 +244,7 @@
          position of the physics raycast wheels relative to the center of
          gravity. Default is to use the corners of the chassis to attach 
          the wheels to. -->
-    <wheels damping-relaxation="20"  damping-compression="4.4" radius="0.25">
+    <wheels damping-relaxation="2.8"  damping-compression="1.4" radius="0.25">
       <front-right position="0.38 0 0.6"  />
       <front-left  position="-0.38 0 0.6" />
       <rear-right  position="0.38 0 -0.6" />
@@ -253,26 +256,22 @@
     <friction slip="10000000"/>
 
     <!-- Values related to stability of the chassis: damping, and reduced
-         impact of roll. -->
+         impact of roll. 
+         downward-impulse-factor: A speed proportional impulse applied each
+           frame that pushes the vehicle onto the ground. 
+         track-connection-accel: An artificial force that pulls a wheel to
+           the ground if its off ground. Reduces the affect if a kart loses
+           contact with the ground (i.e. it then can't steer or accelerate
+           anymore). -->
     <stability roll-influence="0.03"
                chassis-linear-damping="0.2"
-               chassis-angular-damping="0"/>
+               chassis-angular-damping="0"
+               downward-impulse-factor="0.1"
+               track-connection-accel="2"/>
 
     <!-- Parameters for the upright constraint, which keeps karts upright. -->
     <upright tolerance="0.2" max-force="30"/>
 
-    <!-- An artificial force that pulls a wheel to the ground if its off
-         ground. Reduces the affect if a kart loses contact with the ground
-         (i.e. it then can't steer or accelerate anymore). -->
-    <track-connection-accel value="2"/>
-
-    <!-- jump-velocity is the z-axis velocity set when a jump is initiated.
-         This will cause the kart to start rising, till it is pulled back
-         by gravity. A higher value means higher Z velocity, meaning the 
-         kart will rise faster and higher, and will be in the air longer.
-         Notice that jumps are currently disabled, so this value is ignored.  -->
-    <jump velocity="3.0"/>
-
     <!-- collision-side-impulse is an additional (artificial) impulse that
          pushes the slower kart out of the way of the faster karts (i.e. 
          sideways to the faster kart) when a collision happens. This is 

src/config/stk_config.cpp

@@ -38,6 +38,7 @@ STKConfig::~STKConfig()
     if(m_title_music)
         delete m_title_music;
 }   // ~STKConfig
+
 //-----------------------------------------------------------------------------
 /** Loads the stk configuration file. After loading it checks if all necessary
  *  values are actually defined, otherwise an error message is printed and STK

src/karts/kart.cpp

@@ -276,9 +276,7 @@ void Kart::createPhysics()
     // -------------------------
     m_vehicle_raycaster =
         new btKartRaycaster(World::getWorld()->getPhysics()->getPhysicsWorld());
-    m_tuning  = new btKart::btVehicleTuning();
+    m_vehicle = new btKart(m_body, m_vehicle_raycaster, this);
-    m_tuning->m_maxSuspensionTravelCm = m_kart_properties->getSuspensionTravelCM();
-    m_vehicle = new btKart(*m_tuning, m_body, m_vehicle_raycaster);
         //FIXMEJH  m_kart_properties->getTrackConnectionAccel());
 
     // never deactivate the vehicle
@@ -293,13 +291,16 @@ void Kart::createPhysics()
     btVector3 wheel_direction(0.0f, -1.0f, 0.0f);
     btVector3 wheel_axle(-1.0f, 0.0f, 0.0f);
 
+    btKart::btVehicleTuning tuning;
+    tuning.m_maxSuspensionTravelCm = m_kart_properties->getSuspensionTravelCM();
+
     for(unsigned int i=0; i<4; i++)
     {
         bool is_front_wheel = i<2;
         btWheelInfo& wheel = m_vehicle->addWheel(
                             m_kart_model->getWheelPhysicsPosition(i),
                             wheel_direction, wheel_axle, suspension_rest,
-                            wheel_radius, *m_tuning, is_front_wheel);
+                            wheel_radius, tuning, is_front_wheel);
         wheel.m_suspensionStiffness      = m_kart_properties->getSuspensionStiffness();
         wheel.m_wheelsDampingRelaxation  = m_kart_properties->getWheelDampingRelaxation();
         wheel.m_wheelsDampingCompression = m_kart_properties->getWheelDampingCompression();
@@ -416,7 +417,6 @@ Kart::~Kart()
 
     World::getWorld()->getPhysics()->removeKart(this);
     delete m_vehicle;
-    delete m_tuning;
     delete m_vehicle_raycaster;
     delete m_uprightConstraint;
 
@@ -756,7 +756,7 @@ bool Kart::isOnGround() const
 }   // isOnGround
 
 //-----------------------------------------------------------------------------
-/** The kart is near the ground, but not necesarily on it (small jumps). This
+/** The kart is near the ground, but not necessarily on it (small jumps). This
  *  is used to determine when to switch off the upright constraint, so that
  *  explosions can be more violent, while still
 */
@@ -1677,18 +1677,6 @@ void Kart::updatePhysics(float dt)
             }
         }   // !m_brake
     }   // not accelerating
-#ifdef ENABLE_JUMP
-    if(m_controls.jump && isOnGround())
-    {
-      //Vector3 impulse(0.0f, 0.0f, 10.0f);
-      //        getVehicle()->getRigidBody()->applyCentralImpulse(impulse);
-        btVector3 velocity         = m_body->getLinearVelocity();
-        velocity.setZ( m_kart_properties->getJumpVelocity() );
-
-        getBody()->setLinearVelocity( velocity );
-
-    }
-#endif
     if (isOnGround())
     {
         if((fabs(m_controls.m_steer) > 0.001f) && m_controls.m_drift)

src/karts/kart.hpp

@@ -38,13 +38,12 @@
 #include "karts/moveable.hpp"
 #include "karts/kart_model.hpp"
 #include "karts/kart_properties.hpp"
-#include "physics/btKart.hpp"
+//#include "physics/btKart.hpp"
 #include "tracks/terrain_info.hpp"
 #include "utils/no_copy.hpp"
 
 class btKart;
 class btUprightConstraint;
-class btVehicleTuning;
 class Camera;
 class Item;
 class Quad;
@@ -134,7 +133,6 @@ private:
 
     // Bullet physics parameters
     // -------------------------
-    btKart::btVehicleTuning *m_tuning;
     btCompoundShape          m_kart_chassis;
     btVehicleRaycaster      *m_vehicle_raycaster;
     btKart                  *m_vehicle;

src/karts/kart_properties.cpp

@@ -72,7 +72,7 @@ KartProperties::KartProperties(const std::string &filename)
         m_wheel_damping_compression = m_friction_slip = m_roll_influence =
         m_wheel_radius = m_chassis_linear_damping =
         m_chassis_angular_damping = m_suspension_rest =
-        m_max_speed_reverse_ratio = m_jump_velocity =
+        m_max_speed_reverse_ratio = 
         m_rescue_vert_offset = m_upright_tolerance = m_collision_side_impulse =
         m_upright_max_force = m_suspension_travel_cm =
         m_track_connection_accel =
@@ -93,9 +93,10 @@ KartProperties::KartProperties(const std::string &filename)
         m_rescue_time = m_rescue_height = m_explosion_time =
         m_explosion_radius = m_ai_steering_variation = 
         m_swatter_distance2 = m_swatter_duration = m_squash_slowdown =
-        m_squash_duration = UNDEFINED;
+        m_squash_duration = m_downward_impulse_factor = UNDEFINED;
 
     m_gravity_center_shift   = Vec3(UNDEFINED);
+    m_exp_spring_response    = false;
     m_has_skidmarks          = true;
     m_version                = 0;
     m_color                  = video::SColor(255, 0, 0, 0);
@@ -384,9 +385,10 @@ void KartProperties::getAllData(const XMLNode * root)
 
     if(const XMLNode *suspension_node = root->getNode("suspension"))
     {
-        suspension_node->get("stiffness", &m_suspension_stiffness);
+        suspension_node->get("stiffness",           &m_suspension_stiffness);
-        suspension_node->get("rest",      &m_suspension_rest     );
+        suspension_node->get("rest",                &m_suspension_rest     );
-        suspension_node->get("travel-cm", &m_suspension_travel_cm);
+        suspension_node->get("travel-cm",           &m_suspension_travel_cm);
+        suspension_node->get("exp-spring-response", &m_exp_spring_response );
     }
 
     if(const XMLNode *wheels_node = root->getNode("wheels"))
@@ -401,9 +403,16 @@ void KartProperties::getAllData(const XMLNode * root)
 
     if(const XMLNode *stability_node = root->getNode("stability"))
     {
-        stability_node->get("roll-influence",          &m_roll_influence);
+        stability_node->get("roll-influence",          
-        stability_node->get("chassis-linear-damping",  &m_chassis_linear_damping);
+                                                   &m_roll_influence         );
-        stability_node->get("chassis-angular-damping", &m_chassis_angular_damping);
+        stability_node->get("chassis-linear-damping",
+                                                   &m_chassis_linear_damping );
+        stability_node->get("chassis-angular-damping", 
+                                                   &m_chassis_angular_damping);
+        stability_node->get("downward-impulse-factor", 
+                                                   &m_downward_impulse_factor);
+        stability_node->get("track-connection-accel", 
+                                                   &m_track_connection_accel );
     }
 
     if(const XMLNode *upright_node = root->getNode("upright"))
@@ -412,12 +421,6 @@ void KartProperties::getAllData(const XMLNode * root)
         upright_node->get("max-force", &m_upright_max_force);
     }
 
-    if(const XMLNode *track_connection_node = root->getNode("track-connection-accel"))
-        track_connection_node->get("value", &m_track_connection_accel);
-
-    if(const XMLNode *jump_node = root->getNode("jump"))
-        jump_node->get("velocity", &m_jump_velocity);
-
     if(const XMLNode *collision_node = root->getNode("collision"))
         collision_node->get("side-impulse",  &m_collision_side_impulse);
 
@@ -567,8 +570,10 @@ void KartProperties::checkAllSet(const std::string &filename)
     CHECK_NEG(m_wheel_radius,               "wheels radius"                 );
     CHECK_NEG(m_friction_slip,              "friction slip"                 );
     CHECK_NEG(m_roll_influence,             "stability roll-influence"      );
-    CHECK_NEG(m_chassis_linear_damping,     "stability chassis-linear-damping");
+    CHECK_NEG(m_chassis_linear_damping,  "stability chassis-linear-damping" );
-    CHECK_NEG(m_chassis_angular_damping,    "stability chassis-angular-damping");
+    CHECK_NEG(m_chassis_angular_damping, "stability chassis-angular-damping");
+    CHECK_NEG(m_downward_impulse_factor, "stability downward-impulse-factor");
+    CHECK_NEG(m_track_connection_accel,  "stability track-connection-accel" );
     CHECK_NEG(m_engine_power[0],            "engine power[0]"               );
     CHECK_NEG(m_engine_power[1],            "engine power[1]"               );
     CHECK_NEG(m_engine_power[2],            "engine power[2]"               );
@@ -580,11 +585,10 @@ void KartProperties::checkAllSet(const std::string &filename)
     CHECK_NEG(m_suspension_stiffness,       "suspension stiffness"          );
     CHECK_NEG(m_suspension_rest,            "suspension rest"               );
     CHECK_NEG(m_suspension_travel_cm,       "suspension travel-cm"          );
+    CHECK_NEG(m_exp_spring_response,        "suspension exp-string-response");
     CHECK_NEG(m_collision_side_impulse,     "collision side-impulse"        );
-    CHECK_NEG(m_jump_velocity,              "jump velocity"                 );
     CHECK_NEG(m_upright_tolerance,          "upright tolerance"             );
     CHECK_NEG(m_upright_max_force,          "upright max-force"             );
-    CHECK_NEG(m_track_connection_accel,     "track-connection-accel"        );
     CHECK_NEG(m_plunger_in_face_duration[0],"plunger in-face-time[0]"       );
     CHECK_NEG(m_plunger_in_face_duration[1],"plunger in-face-time[1]"       );
     CHECK_NEG(m_plunger_in_face_duration[2],"plunger in-face-time[2]"       );

src/karts/kart_properties.hpp

@@ -85,7 +85,7 @@ private:
 
     // Display and gui
     // ---------------
-    std::string m_name;        /**< The human readable Name of the kart
+    std::string m_name;               /**< The human readable Name of the kart
                                        *   driver. */
     std::string m_ident;              /**< The computer readable-name of the
                                        *   kart driver. */
@@ -217,21 +217,41 @@ private:
     float m_friction_slip;
     float m_roll_influence;
     float m_wheel_radius;
+
+    /** An impulse pushing the kart down which is proportional to speed. So
+     *  the actual impulse is  speed * m_downward_force_factor. Set it to
+     *  0 to disable completely. Based on
+     *  http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=6059\
+     *  &p=21240&hilit=vehicle#p21240  */
+    float m_downward_impulse_factor;
+
+    /** Artifical acceleration that pulls a kart down onto the track if one 
+     *  axis loses contact with the track. */
+    float m_track_connection_accel;
+
+    /** Linear damping of the chassis to prevent it from toppling over. */
     float m_chassis_linear_damping;
+
+    /** Angular damping to prevent it from turning too easily. */
     float m_chassis_angular_damping;
+
     float m_max_speed[3];
     float m_max_speed_reverse_ratio;
-    Vec3  m_gravity_center_shift;    /**< Shift of center of gravity. */
+
-    float m_track_connection_accel;  /**< Artifical acceleration that pulls a
+    /** Shift of center of gravity. */
-                                      *   kart down onto the track if one axis
+    Vec3  m_gravity_center_shift;
-                                      *   loses contact with the track. */
+
+    /** The suspension reaction is dampened to reach an exponential behaviour.
+     *  See http://bulletphysics.org/Bullet/phpBB3/viewtopic.php?f=9&t=7369\
+     *  &p=25236&hilit=vehicle#p25236  for details. */
+    bool  m_exp_spring_response;
+
     float m_suspension_rest;
     float m_suspension_travel_cm;
     /** An additional artifical side-impulse that pushes the slower kart
      *  out of the way of the faster kart in case of a collision. */
     float m_collision_side_impulse;
-    /** Vertical velocity set when jumping. */
+
-    float m_jump_velocity;
     float m_upright_tolerance;
     float m_upright_max_force;
 
@@ -418,6 +438,9 @@ public:
     float getChassisAngularDamping  () const 
                                            {return m_chassis_angular_damping; }
 
+    /** Returns artificial acceleration to keep wheels on track. */
+    float getTrackConnectionAccel   () const {return m_track_connection_accel;}
+
     /** Returns the maximum speed dependent on the difficult level. */
     float getMaxSpeed               () const {return
                                    m_max_speed[race_manager->getDifficulty()];}
@@ -456,8 +479,8 @@ public:
     /** Returns the amount the suspension can extend. */
     float getSuspensionTravelCM     () const {return m_suspension_travel_cm;  }
 
-    /** Returns jump velocity (unused atm). */
+    /** Returns if the spring should be exponentially dampened. */
-    float getJumpVelocity           () const {return m_jump_velocity;         }
+    bool getExpSpringResponse() const {return m_exp_spring_response; }
 
     /** Returns the (artificial) collision side impulse this kart will apply
      *  to a slower kart in case of a collision. */
@@ -491,9 +514,6 @@ public:
     /** Returns the maximum value of the upright counteracting force. */
     float getUprightMaxForce        () const {return m_upright_max_force;     }
 
-    /** Returns artificial acceleration to keep wheels on track. */
-    float getTrackConnectionAccel   () const {return m_track_connection_accel;}
-
     /** Returns the maximum length of a rubber band before it breaks. */
     float getRubberBandMaxLength    () const {return m_rubber_band_max_length;}
 

src/physics/btKart.cpp

@@ -32,25 +32,25 @@ btRigidBody& btActionInterface::getFixedBody()
 	return s_fixed;
 }
 
-btKart::btKart(const btVehicleTuning& tuning,btRigidBody* chassis,	btVehicleRaycaster* raycaster )
+btKart::btKart(btRigidBody* chassis, btVehicleRaycaster* raycaster, 
-:m_vehicleRaycaster(raycaster),
+               Kart *kart)
-m_pitchControl(btScalar(0.))
+      : m_vehicleRaycaster(raycaster),
+        m_pitchControl(btScalar(0.))
 {
 	m_chassisBody = chassis;
 	m_indexRightAxis = 0;
 	m_indexUpAxis = 2;
 	m_indexForwardAxis = 1;
-	defaultInit(tuning);
+	defaultInit();
     m_num_wheels_on_ground = 0;
+    m_kart = kart;
 }
 
 
-void btKart::defaultInit(const btVehicleTuning& tuning)
+void btKart::defaultInit()
 {
-	(void)tuning;
 	m_currentVehicleSpeedKmHour = btScalar(0.);
 	m_steeringValue = btScalar(0.);	
-	
 }
 
 	

src/physics/btKart.hpp

@@ -20,6 +20,7 @@ class btDynamicsWorld;
 #include "BulletDynamics/Dynamics/btActionInterface.h"
 
 class btVehicleTuning;
+class Kart;
 
 ///rayCast vehicle, very special constraint that turn a rigidbody into a vehicle.
 class btKart : public btActionInterface
@@ -72,12 +73,18 @@ protected:
 	int m_indexUpAxis;
 	int	m_indexForwardAxis;
 
-	void defaultInit(const btVehicleTuning& tuning);
+    /** The STK kart object which uses this vehicle. This is mostly used to 
+     *  get access to the kart properties, which also define physics 
+     *  properties. */
+    Kart *m_kart;
+
+	void defaultInit();
 
 public:
 
 	//constructor to create a car from an existing rigidbody
-	btKart(const btVehicleTuning& tuning,btRigidBody* chassis,	btVehicleRaycaster* raycaster );
+	btKart(btRigidBody* chassis, btVehicleRaycaster* raycaster,
+           Kart *kart);
 
 	virtual ~btKart() ;