Merge branch 'Characteristics' of git://github.com/STK-helper/stk-code into dev

data/kart_characteristics.xml

@@ -66,7 +66,7 @@
                 speed 10 the radius is 7.5 etc.
                 The actual turn radius is piece-wise linearly interpolated. This
                 allows for tighter turning at lower speeds, and also avoids that
-                the kart becomes too hard to control at high speed (speeds of
+                the kart becomes too hard to control at high speed (speeds
                 higher than 25 can only be reached with powerups).
             time-full-steer: This is the amount of change in steering depending
                 on current steering. So if the steering is between 0 and 0.5,
@@ -84,7 +84,8 @@
               time-reset-steer="0.1" />
 
         <!-- Speed and acceleration
-            power: The power of the kart
+            power: The power of the kart (the engine power needed to accelerate
+                   at a given pace is proportional to mass)
             max-speed: The base maximum speed of the kart in m/s
             brake-factor: Value used when braking.
             brake-time-increase: The brake force is multiplied by
@@ -93,18 +94,19 @@
             max-speed-reverse-ratio is the percentage of max speed for reverse
                 gear.
           -->
-        <engine power="875" max-speed="25" brake-factor="15"
+        <engine power="950" max-speed="25" brake-factor="15"
                 brake-time-increase="6" max-speed-reverse-ratio="0.65" />
 
         <!-- Simulated gears
             switch-ratio defines at what ratio of the maximum
                 speed what gear is selected, e.g. 0.25 means that if the speed is
-                bigger or equal to 0.25 * maxSpeed then use gear 1, 0.5 means if
+                inferior or equal to 0.25 * maxSpeed then use gear 1, 0.5 means if
-                the speed is bigger or equal to 0.5 x maxSpeed then gear 2.
+                the speed is inferior or equal to 0.5 x maxSpeed then gear 2.
                 gear-power-increase contains the increase in max power (to simulate
                 different gears), e.g. 2.5 as first entry means: 2.5 * maxPower in gear 1
                 | first  | second |  third | . -->
-        <gear switch-ratio="0.25 0.7 1.0" power-increase="2.2 1.7 1.3" />
+        <gear switch-ratio="0.2 0.45 0.7 1 1.25"
+              power-increase="2.5 2.1 1.7 1.4 1.2" />
 
         <!-- Mass of a kart -->
         <mass value="350" />
@@ -205,9 +207,9 @@
         <anvil duration="2.0" weight="150"  speed-factor="0.2" />
 
         <!-- Parachute
-            friction: The friction increase when a parachute is attached.
+            friction: The friction factor when a parachute is attached.
             duration: The time an attached parachute is active
-            duration-other: The time a parachute attached from other kart works
+            duration-other: Used when the parachute results from item use
             duration-rank-mult: The multiplier applied to the duration of the
             parachute on the 1st kart when affected by the item. Scale for
             intermediary ranks to 1.0 for the last affected.
@@ -220,9 +222,9 @@
                 detach parachute. E.g. at max-speed 50% of speed must be lost.
             max-speed: A factor that decides the impact of rate of speed
                 (distance between bounds) -->
-        <parachute friction="2.0" duration="2.0" duration-other="2.6"
+        <parachute friction="5.0" duration="3" duration-other="2.5"
-                   duration-rank-mult="1.35" duration-speed-mult="2.0"
+                   duration-rank-mult="1.5" duration-speed-mult="1.35"
-                   lbound-fraction="0.8" ubound-fraction="0.5" max-speed="23" />
+                   lbound-fraction="0.5" ubound-fraction="0.3" max-speed="30" />
         <!-- Bubblegum
             duration: How long the bubblegum lasts.
             speed-fraction: To what fraction of top-speed the speed is reduced.
@@ -273,7 +275,7 @@
             fields must have the same size, and must be sorted by
             increasing times. -->
         <startup time="0.3 0.5"
-                 boost="6 3" />
+                 boost="8 4" />
 
         <!-- Rescue
             duration: How long it takes the kart to be raised.
@@ -292,11 +294,12 @@
                 after being hit by an explosion.
             radius: Kart closer to this value will be affected by
                 an explosion as well.  -->
-        <explosion duration="2" radius="5"
+        <explosion duration="2" radius="6"
-                   invulnerability-time="6" />
+                   invulnerability-time="7" />
 
         <!-- Nitro
             engine-force: additional engine power
+            engine-mult: multiply the total engine power by this
             consumption: nitro consumption - heavier characters can be set
                 to need more nitro than lighter character.
             small-container: how much energy a small container gives.
@@ -308,8 +311,9 @@
             fade-out-time: Duration during which the increased maximum
                 speed due to nitro fades out.
             max: How much nitro a kart can store. -->
-        <nitro engine-force="600" consumption="1" small-container="1" big-container="3"
+        <nitro engine-force="300" engine-mult="1.2" consumption="1"
-               max-speed-increase="5" duration="1" fade-out-time="2" max="20" />
+               small-container="1" big-container="3"
+               max-speed-increase="5" duration="1" fade-out-time="2.4" max="20" />
 
         <!-- Slipstream
             base-speed: the speed for which length and width are valid.
@@ -331,22 +335,22 @@
             fade-out-time: How long the slip stream speed increase will
                 gradually be reduced.  -->
         <slipstream base-speed="20" length="8" width="4" inner-factor="0.5"
-                    min-collect-time="3" max-collect-time="8" add-power="300" min-speed="8"
+                    min-collect-time="2.5" max-collect-time="8" add-power="300" min-speed="8"
-                    max-speed-increase="5" duration-factor="1" fade-out-time="2" />
+                    max-speed-increase="3" duration-factor="1" fade-out-time="2" />
     </characteristic>
 
     <!-- The different difficulties (like easy, medium, hard) -->
     <difficulties>
         <characteristic name="easy">
-            <engine power="*0.66" max-speed="*0.6" />
+            <engine power="*0.7" max-speed="*0.6" />
             <plunger in-face-time="3" />
         </characteristic>
         <characteristic name="medium">
-            <engine power="*0.77" max-speed="*0.8" />
+            <engine power="*0.83" max-speed="*0.8" />
             <plunger in-face-time="4" />
         </characteristic>
         <characteristic name="hard">
-            <engine power="*0.89" max-speed="*0.92" />
+            <engine power="*0.92" max-speed="*0.92" />
         </characteristic>
         <!-- This doesn't need to be changed because the most fast/heavy/extreme
             values should also be the default ones. -->
@@ -356,44 +360,40 @@
     <!-- The different kart types, that can be specified in the kart.xml file -->
     <kart-types>
         <characteristic name="light">
-            <engine power="*0.46" max-speed="*0.92" brake-factor="*1"
+            <turn radius="0:2.0 10:7.5 25:15 45:30" />
-                 max-speed-reverse-ratio="*0.77" />
+            <engine power="*0.8" max-speed="*0.95" brake-factor="*1"
-            <gear switch-ratio="0.20 0.55 1" power-increase="5 4 3" />
+                 max-speed-reverse-ratio="*0.8" />
-            <mass value="*0.56" />
+            <gear switch-ratio="0.1 0.25 0.45 0.7 1.0 4.0"
-            <startup time="0.3 0.5"
+                  power-increase="2.8 2.3 1.9 1.5 1.25 1.0" />
-                     boost="8.5 4.5" />
+            <mass value="*0.6" />
-            <explosion time="2.1" radius="5.5"
+            <startup boost="*1 *1" />
-                       invulnerability-time="7" />
+            <explosion time="*1" radius="*1" />
-            <nitro engine-force="350" max-speed-increase="4.5" duration="1.5"
+            <nitro engine-force="*0.6" max-speed-increase="*0.9" duration="*1" />
-                   fade-out-time="2.5" />
             <slipstream length="*0.9" collect-time="*0.9"
                         duration-factor="*1" fade-out-time="*1" />
         </characteristic>
         <characteristic name="medium">
-            <engine power="*0.63" max-speed="*1" brake-factor="*0.73"
+            <turn radius="0:2.3 10:8.625 25:17.25 45:34.5" />
-                    max-speed-reverse-ratio="*0.62" />
+            <engine power="*0.875" max-speed="*1" brake-factor="*0.8"
-            <gear switch-ratio="0.30 0.7 1.0" power-increase="2.2 2.2 2.5" />
+                    max-speed-reverse-ratio="*0.75" />
-            <mass value="*0.71" />
+            <gear switch-ratio="0.1 0.25 0.45 0.7 1 4"
-            <startup time="0.3 0.5"
+                  power-increase="2.4 2 1.7 1.4 1.2 1" />
-                     boost="4.2 2.6" />
+            <mass value="*0.75" />
-            <explosion time="1.8" radius="5"
+            <startup boost="*0.8 *0.8" />
-                       invulnerability-time="6" />
+            <explosion time="*0.8" radius="*0.8" />
-            <nitro engine-force="425" consumption="1.4" duration="1" />
+            <nitro engine-force="*0.75" consumption="*1.25" />
             <slipstream duration-factor="*0.8" fade-out-time="*1" />
         </characteristic>
         <characteristic name="heavy">
-            <engine power="*1" max-speed="*1" brake-factor="*0.66"
+            <turn radius="0:2.6 10:9.75 25:19.5 45:39" />
-                    max-speed-reverse-ratio="*1" />
+            <engine power="*1" max-speed="*1.05" brake-factor="*0.6"
-            <gear switch-ratio="0.45 0.70 1" power-increase="1.5 1.7 2.5" />
+                    max-speed-reverse-ratio="*0.7" />
+            <gear switch-ratio="0.1 0.25 0.45 0.7 1 4"
+                  power-increase="2 1.7 1.5 1.3 1.15 1" />
             <mass value="*1" />
-            <swatter duration="10" distance="3" squash-duration="5"
+            <startup boost="*0.6 *0.6" />
-                     squash-slowdown="0.5" />
+            <explosion time="*0.6" radius="*0.6" />
-            <startup time="0.3 0.5"
+            <nitro engine-force="*1" consumption="*1.67" max-speed-increase="*1.1" />
-                     boost="3.8 2" />
-            <explosion time="1.5" radius="4"
-                       invulnerability-time="6" />
-            <nitro engine-force="600" consumption="2" max-speed-increase="8"
-                   duration="0.7" fade-out-time="1.3" />
             <slipstream length="*1.1" collect-time="*1.1"
                    duration-factor="*0.6" fade-out-time="*1" />
         </characteristic>

src/karts/abstract_characteristic.cpp

@@ -201,6 +201,8 @@ AbstractCharacteristic::ValueType AbstractCharacteristic::getType(
         return TYPE_FLOAT;
     case NITRO_ENGINE_FORCE:
         return TYPE_FLOAT;
+    case NITRO_ENGINE_MULT:
+        return TYPE_FLOAT;
     case NITRO_CONSUMPTION:
         return TYPE_FLOAT;
     case NITRO_SMALL_CONTAINER:
@@ -437,6 +439,8 @@ std::string AbstractCharacteristic::getName(CharacteristicType type)
         return "NITRO_DURATION";
     case NITRO_ENGINE_FORCE:
         return "NITRO_ENGINE_FORCE";
+    case NITRO_ENGINE_MULT:
+        return "NITRO_ENGINE_MULT";
     case NITRO_CONSUMPTION:
         return "NITRO_CONSUMPTION";
     case NITRO_SMALL_CONTAINER:
@@ -1395,6 +1399,18 @@ float AbstractCharacteristic::getNitroEngineForce() const
     return result;
 }  // getNitroEngineForce
 
+// ----------------------------------------------------------------------------
+float AbstractCharacteristic::getNitroEngineMult() const
+{
+    float result;
+    bool is_set = false;
+    process(NITRO_ENGINE_MULT, &result, &is_set);
+    if (!is_set)
+        Log::fatal("AbstractCharacteristic", "Can't get characteristic %s",
+                    getName(NITRO_ENGINE_MULT).c_str());
+    return result;
+}  // getNitroEngineMult
+
 // ----------------------------------------------------------------------------
 float AbstractCharacteristic::getNitroConsumption() const
 {

src/karts/abstract_characteristic.hpp

@@ -185,6 +185,7 @@ public:
         // Nitro
         NITRO_DURATION,
         NITRO_ENGINE_FORCE,
+        NITRO_ENGINE_MULT,
         NITRO_CONSUMPTION,
         NITRO_SMALL_CONTAINER,
         NITRO_BIG_CONTAINER,
@@ -354,6 +355,7 @@ public:
 
     float getNitroDuration() const;
     float getNitroEngineForce() const;
+    float getNitroEngineMult() const;
     float getNitroConsumption() const;
     float getNitroSmallContainer() const;
     float getNitroBigContainer() const;

src/karts/kart.cpp

@@ -2651,6 +2651,54 @@ void Kart::updateEngineSFX(float dt)
       }
 }   // updateEngineSFX
 
+
+
+//-----------------------------------------------------------------------------
+/** Reduces the engine power according to speed
+ *  
+ *  TODO : find where the physics already apply a linear force decrease
+ *  TODO : While this work fine, it should ideally be in physics
+ *         However, the function use some kart properties and parachute
+ *         effect needs to be applied, so keep both working if moving
+ *  \param engine_power : the engine power on which to apply the decrease
+ */
+float Kart::applyAirFriction(float engine_power)
+{
+    //The physics already do that a certain amount of engine force is needed to keep going
+    //at a given speed (~39,33 engine force = 1 speed for a mass of 350)
+    //But it's either too slow to accelerate to a target speed or makes it
+    //too easy to accelerate farther.
+    //Instead of making increasing gears have enormous power gaps, apply friction
+
+    float mass_factor = m_kart_properties->getMass()/350.0f;
+    float compense_linear_slowdown = 39.33f*getSpeed()*mass_factor;
+
+    engine_power += compense_linear_slowdown;
+
+    // The result will always be a positive number
+    float friction_intensity = fabsf(getSpeed());
+
+    // Not a pure quadratic evolution as it would be too brutal
+    friction_intensity *= sqrt(friction_intensity)*5;
+
+    // Apply parachute physics
+    // Currently, all karts have the same base friction
+    // If this is changed, a compensation needs to be added here
+    if(m_attachment->getType()==Attachment::ATTACH_PARACHUTE)
+        friction_intensity *= m_kart_properties->getParachuteFriction();
+
+    if (friction_intensity < 0.0f) friction_intensity = 0.0f;
+
+    // We substract the friction from the engine power
+    // 1)This is the logical behavior
+    // 2)That way, engine boosts remain useful at high speed
+    // 3)It helps heavier karts, who have an higher engine power
+
+    engine_power-=friction_intensity;
+
+    return engine_power;
+} //applyAirFriction
+
 //-----------------------------------------------------------------------------
 /** Sets the engine power. It considers the engine specs, items that influence
  *  the available power, and braking/steering.
@@ -2661,9 +2709,11 @@ void Kart::updateEnginePowerAndBrakes(int ticks)
     updateNitro(ticks);
     float engine_power = getActualWheelForce();
 
-    // apply parachute physics if relevant
+    // apply nitro boost if relevant
-    if(m_attachment->getType()==Attachment::ATTACH_PARACHUTE)
+    if(getSpeedIncreaseTicksLeft(MaxSpeed::MS_INCREASE_NITRO) > 0)
-        engine_power*=0.2f;
+    {
+        engine_power*= m_kart_properties->getNitroEngineMult();
+    }
 
     // apply bubblegum physics if relevant
     if (m_bubblegum_ticks > 0)
@@ -2689,6 +2739,9 @@ void Kart::updateEnginePowerAndBrakes(int ticks)
             m_kart_properties->getSkidVisualTime() == 0)
             engine_power *= 0.5f;
 
+        // This also applies parachute physics if relevant
+        engine_power = applyAirFriction(engine_power);
+
         applyEngineForce(engine_power*m_controls.getAccel());
 
         // Either all or no brake is set, so test only one to avoid
@@ -2698,14 +2751,20 @@ void Kart::updateEnginePowerAndBrakes(int ticks)
             m_vehicle->setAllBrakes(0);
         m_brake_ticks = 0;
     }
-    else
+    else // not accelerating
-    {   // not accelerating
+    {
+        //The engine power is still guaranteed >= 0 at this point
+        float braking_power = engine_power;
+
+        // This also applies parachute physics if relevant
+        engine_power = applyAirFriction(engine_power);
+       
         if(m_controls.getBrake())
         {   // check if the player is currently only slowing down
             // or moving backwards
             if(m_speed > 0.0f)
             {   // Still going forward while braking
-                applyEngineForce(-engine_power*2.5f);
+                applyEngineForce(engine_power-braking_power*3);
                 m_brake_ticks += ticks;
                 // Apply the brakes - include the time dependent brake increase
                 float f = 1.0f + stk_config->ticks2Time(m_brake_ticks)
@@ -2723,7 +2782,7 @@ void Kart::updateEnginePowerAndBrakes(int ticks)
                     // The backwards acceleration is artificially increased to
                     // allow players to get "unstuck" quicker if they hit e.g.
                     // a wall.
-                    applyEngineForce(-engine_power*2.5f);
+                    applyEngineForce(engine_power-braking_power*3);
                 }
                 else  // -m_speed >= max speed on this terrain
                 {
@@ -2732,13 +2791,13 @@ void Kart::updateEnginePowerAndBrakes(int ticks)
 
             }   // m_speed <00
         }
-        else   // !m_brake
+        else   // no braking and no acceleration
         {
             m_brake_ticks = 0;
-            // lift the foot from throttle, brakes with 10% engine_power
+            // lift the foot from throttle, let friction slow it down
             assert(!std::isnan(m_controls.getAccel()));
             assert(!std::isnan(engine_power));
-            applyEngineForce(-m_controls.getAccel()*engine_power*0.1f);
+            applyEngineForce(engine_power-braking_power);
 
             // If not giving power (forward or reverse gear), and speed is low
             // we are "parking" the kart, so in battle mode we can ambush people
@@ -2746,7 +2805,7 @@ void Kart::updateEnginePowerAndBrakes(int ticks)
                 m_vehicle->setAllBrakes(20.0f);
             else
                 m_vehicle->setAllBrakes(0);
-        }   // !m_brake
+        }   // no braking and no acceleration
     }   // not accelerating
 }   // updateEnginePowerAndBrakes
 

src/karts/kart.hpp

@@ -264,6 +264,7 @@ protected:
     void          updateEngineSFX(float dt);
     void          updateSpeed();
     void          updateNitro(int ticks);
+    float         applyAirFriction (float engine_power);
     float         getActualWheelForce();
     void          playCrashSFX(const Material* m, AbstractKart *k);
     void          loadData(RaceManager::KartType type, bool animatedModel);

src/karts/kart_properties.cpp

@@ -1017,6 +1017,12 @@ float KartProperties::getNitroEngineForce() const
     return m_cached_characteristic->getNitroEngineForce();
 }  // getNitroEngineForce
 
+// ----------------------------------------------------------------------------
+float KartProperties::getNitroEngineMult() const
+{
+    return m_cached_characteristic->getNitroEngineMult();
+}  // getNitroEngineMult
+
 // ----------------------------------------------------------------------------
 float KartProperties::getNitroConsumption() const
 {

src/karts/kart_properties.hpp

@@ -469,6 +469,7 @@ public:
 
     float getNitroDuration() const;
     float getNitroEngineForce() const;
+    float getNitroEngineMult() const;
     float getNitroConsumption() const;
     float getNitroSmallContainer() const;
     float getNitroBigContainer() const;

src/karts/skidding.cpp

@@ -545,7 +545,7 @@ void Skidding::update(int ticks, bool is_on_ground,
                                                             MaxSpeed::MS_INCREASE_RED_SKIDDING;
                     m_kart->m_max_speed->
                         instantSpeedIncrease(bonus_cat,
-                               bonus_speed, bonus_speed,
+                               bonus_speed, bonus_speed/2,
                                bonus_force,
                                stk_config->time2Ticks(bonus_time),
                                /*fade-out-time*/ stk_config->time2Ticks(1.0f));

src/karts/xml_characteristic.cpp

@@ -545,6 +545,8 @@ void XmlCharacteristic::load(const XMLNode *node)
             &m_values[NITRO_DURATION]);
         sub_node->get("engine-force",
             &m_values[NITRO_ENGINE_FORCE]);
+        sub_node->get("engine-mult",
+            &m_values[NITRO_ENGINE_MULT]);
         sub_node->get("consumption",
             &m_values[NITRO_CONSUMPTION]);
         sub_node->get("small-container",