Implemented force feedback

src/app/app.cpp

@@ -91,6 +91,8 @@ struct ApplicationPrivate
     SDL_Joystick *joystick;
     //! Id of joystick timer
     SDL_TimerID joystickTimer;
+    //! Haptic subsystem for the joystick
+    SDL_Haptic *haptic;
 
     ApplicationPrivate()
     {
@@ -100,6 +102,7 @@ struct ApplicationPrivate
         glcontext = nullptr;
         joystick = nullptr;
         joystickTimer = 0;
+        haptic = nullptr;
     }
 };
 
@@ -516,6 +519,10 @@ bool CApplication::Create()
     {
         GetLogger()->Warn("Joystick subsystem init failed\nJoystick(s) will not be available\n");
     }
+    if (SDL_InitSubSystem(SDL_INIT_HAPTIC) < 0)
+    {
+        GetLogger()->Warn("Joystick haptic subsystem init failed\nForce feedback will not be available\n");
+    }
 
     if ((IMG_Init(IMG_INIT_PNG) & IMG_INIT_PNG) == 0)
     {
@@ -725,6 +732,20 @@ bool CApplication::OpenJoystick()
     // Create a timer for polling joystick state
     m_private->joystickTimer = SDL_AddTimer(JOYSTICK_TIMER_INTERVAL, JoystickTimerCallback, nullptr);
 
+    // Initialize haptic subsystem
+    m_private->haptic = SDL_HapticOpenFromJoystick(m_private->joystick);
+    if (m_private->haptic == nullptr)
+    {
+        GetLogger()->Warn("Haptic subsystem open failed\n");
+        return true;
+    }
+
+    if (SDL_HapticRumbleInit(m_private->haptic) != 0)
+    {
+        GetLogger()->Warn("Haptic rumble effect init failed\n");
+        return true;
+    }
+
     return true;
 }
 
@@ -734,6 +755,11 @@ void CApplication::CloseJoystick()
 
     GetLogger()->Info("Closing joystick\n");
 
+    StopForceFeedbackEffect();
+
+    SDL_HapticClose(m_private->haptic);
+    m_private->haptic = nullptr;
+
     SDL_JoystickClose(m_private->joystick);
     m_private->joystick = nullptr;
 }
@@ -1784,3 +1810,20 @@ void CApplication::SetTextInput(bool textInputEnabled)
         SDL_StopTextInput();
     }
 }
+
+void CApplication::PlayForceFeedbackEffect(float strength, int length)
+{
+    if (m_private->haptic == nullptr) return;
+
+    GetLogger()->Trace("Force feedback! length = %d ms, strength = %.2f\n", length, strength);
+    if (SDL_HapticRumblePlay(m_private->haptic, strength, length) != 0)
+    {
+        GetLogger()->Debug("Failed to play haptic effect\n");
+    }
+}
+
+void CApplication::StopForceFeedbackEffect()
+{
+    if (m_private->haptic == nullptr) return;
+    SDL_HapticRumbleStop(m_private->haptic);
+}

src/app/app.h

@@ -314,6 +314,11 @@ public:
     //! Renders the image in window if needed
     void        RenderIfNeeded(int updateRate);
 
+    //! Starts a force feedback effect on the joystick
+    void        PlayForceFeedbackEffect(float strength = 1.0f, int length = 999999);
+    //! Stops a force feedback effect on the joystick
+    void        StopForceFeedbackEffect();
+
 protected:
     //! Creates the window's SDL_Surface
     bool CreateVideoSurface();

src/graphics/engine/camera.cpp

@@ -570,6 +570,8 @@ void CCamera::FlushEffect()
     m_effectForce    = 0.0f;
     m_effectProgress = 0.0f;
     m_effectOffset   = Math::Vector(0.0f, 0.0f, 0.0f);
+
+    CApplication::GetInstancePointer()->StopForceFeedbackEffect();
 }
 
 void CCamera::StartEffect(CameraEffect effect, Math::Vector pos, float force)
@@ -655,6 +657,25 @@ void CCamera::EffectFrame(const Event &event)
     force *= 1.0f-dist;
     m_effectOffset *= force;
 
+    float forceFeedback = force;
+    if (m_effectType == CAM_EFFECT_VIBRATION)
+    {
+        forceFeedback *= 0.5f;
+    }
+    if (m_effectType == CAM_EFFECT_PET)
+    {
+        forceFeedback *= 0.75f;
+    }
+    if (m_effectType == CAM_EFFECT_EXPLO)
+    {
+        forceFeedback *= 3.0f;
+    }
+    if (forceFeedback > 1.0f) forceFeedback = 1.0f;
+    if (forceFeedback >= 0.1f)
+    {
+        CApplication::GetInstancePointer()->PlayForceFeedbackEffect(forceFeedback);
+    }
+
     if (m_effectProgress >= 1.0f)
         FlushEffect();
 }