From e32bc1a0a38d466a2c85c0386938119f573ec9ef Mon Sep 17 00:00:00 2001
From: Konstantin Budnikov <kard@bk.ru>
Date: Thu, 21 Feb 2019 06:22:38 +0300
Subject: [PATCH] SDL_HapticRumblePlay rumble for gamepad without
 SDL_HAPTIC_LEFTRIGHT support (#181)

---
 app/streaming/input.cpp | 58 +++++++++++++++++++++++++++++------------
 app/streaming/input.h   |  8 ++++++
 2 files changed, 49 insertions(+), 17 deletions(-)

diff --git a/app/streaming/input.cpp b/app/streaming/input.cpp
index 8d40a1a5..1bbcc371 100644
--- a/app/streaming/input.cpp
+++ b/app/streaming/input.cpp
@@ -775,9 +775,21 @@ void SdlInputHandler::handleControllerDeviceEvent(SDL_ControllerDeviceEvent* eve
         state->jsId = SDL_JoystickInstanceID(SDL_GameControllerGetJoystick(state->controller));
         state->haptic = SDL_HapticOpenFromJoystick(SDL_GameControllerGetJoystick(state->controller));
         state->hapticEffectId = -1;
-        if (state->haptic != nullptr && (SDL_HapticQuery(state->haptic) & SDL_HAPTIC_LEFTRIGHT) == 0) {
-            SDL_HapticClose(state->haptic);
-            state->haptic = nullptr;
+        state->hapticMethod = GAMEPAD_HAPTIC_METHOD_NONE;
+        if (state->haptic != nullptr) {
+            if ((SDL_HapticQuery(state->haptic) & SDL_HAPTIC_LEFTRIGHT) == 0) {
+                if (SDL_HapticRumbleSupported(state->haptic)) {
+                    if (SDL_HapticRumbleInit(state->haptic) == 0) {
+                        state->hapticMethod = GAMEPAD_HAPTIC_METHOD_SIMPLERUMBLE;
+                    }
+                }
+                if (state->hapticMethod == GAMEPAD_HAPTIC_METHOD_NONE) {
+                    SDL_HapticClose(state->haptic);
+                    state->haptic = nullptr;
+                }
+            } else {
+                state->hapticMethod = GAMEPAD_HAPTIC_METHOD_LEFTRIGHT;
+            }
         }
 
         SDL_JoystickGetGUIDString(SDL_JoystickGetGUID(SDL_GameControllerGetJoystick(state->controller)),
@@ -883,8 +895,12 @@ void SdlInputHandler::rumble(unsigned short controllerNumber, unsigned short low
     }
 
     // Stop the last effect we played
-    if (m_GamepadState[controllerNumber].hapticEffectId >= 0) {
-        SDL_HapticDestroyEffect(haptic, m_GamepadState[controllerNumber].hapticEffectId);
+    if (m_GamepadState[controllerNumber].hapticMethod == GAMEPAD_HAPTIC_METHOD_LEFTRIGHT) {
+        if (m_GamepadState[controllerNumber].hapticEffectId >= 0) {
+            SDL_HapticDestroyEffect(haptic, m_GamepadState[controllerNumber].hapticEffectId);
+        }
+    } else if (m_GamepadState[controllerNumber].hapticMethod == GAMEPAD_HAPTIC_METHOD_SIMPLERUMBLE) {
+        SDL_HapticRumbleStop(haptic);
     }
 
     // If this callback is telling us to stop both motors, don't bother queuing a new effect
@@ -892,22 +908,30 @@ void SdlInputHandler::rumble(unsigned short controllerNumber, unsigned short low
         return;
     }
 
-    SDL_HapticEffect effect;
-    SDL_memset(&effect, 0, sizeof(effect));
-    effect.type = SDL_HAPTIC_LEFTRIGHT;
+    if (m_GamepadState[controllerNumber].hapticMethod == GAMEPAD_HAPTIC_METHOD_LEFTRIGHT) {
+        SDL_HapticEffect effect;
+        SDL_memset(&effect, 0, sizeof(effect));
+        effect.type = SDL_HAPTIC_LEFTRIGHT;
 
-    // The effect should last until we are instructed to stop or change it
-    effect.leftright.length = SDL_HAPTIC_INFINITY;
+        // The effect should last until we are instructed to stop or change it
+        effect.leftright.length = SDL_HAPTIC_INFINITY;
 
-    // SDL haptics range from 0-32767 but XInput uses 0-65535, so divide by 2 to correct for SDL's scaling
-    effect.leftright.large_magnitude = lowFreqMotor / 2;
-    effect.leftright.small_magnitude = highFreqMotor / 2;
+        // SDL haptics range from 0-32767 but XInput uses 0-65535, so divide by 2 to correct for SDL's scaling
+        effect.leftright.large_magnitude = lowFreqMotor / 2;
+        effect.leftright.small_magnitude = highFreqMotor / 2;
 
-    // Play the new effect
-    m_GamepadState[controllerNumber].hapticEffectId = SDL_HapticNewEffect(haptic, &effect);
-    if (m_GamepadState[controllerNumber].hapticEffectId >= 0) {
-        SDL_HapticRunEffect(haptic, m_GamepadState[controllerNumber].hapticEffectId, 1);
+        // Play the new effect
+        m_GamepadState[controllerNumber].hapticEffectId = SDL_HapticNewEffect(haptic, &effect);
+        if (m_GamepadState[controllerNumber].hapticEffectId >= 0) {
+            SDL_HapticRunEffect(haptic, m_GamepadState[controllerNumber].hapticEffectId, 1);
+        }
+    } else if (m_GamepadState[controllerNumber].hapticMethod == GAMEPAD_HAPTIC_METHOD_SIMPLERUMBLE) {
+        SDL_HapticRumblePlay(haptic,
+                             std::min(1.0, (GAMEPAD_HAPTIC_SIMPLE_HIFREQ_MOTOR_WEIGHT*highFreqMotor +
+                                            GAMEPAD_HAPTIC_SIMPLE_LOWFREQ_MOTOR_WEIGHT*lowFreqMotor) / 65535.0),
+                             SDL_HAPTIC_INFINITY);
     }
+
 }
 
 void SdlInputHandler::handleTouchFingerEvent(SDL_TouchFingerEvent* event)
diff --git a/app/streaming/input.h b/app/streaming/input.h
index c29a8636..e55b7d64 100644
--- a/app/streaming/input.h
+++ b/app/streaming/input.h
@@ -9,6 +9,7 @@ struct GamepadState {
     SDL_GameController* controller;
     SDL_JoystickID jsId;
     SDL_Haptic* haptic;
+    int hapticMethod;
     int hapticEffectId;
     short index;
 
@@ -21,6 +22,13 @@ struct GamepadState {
 #define MAX_GAMEPADS 4
 #define MAX_FINGERS 2
 
+#define GAMEPAD_HAPTIC_METHOD_NONE 0
+#define GAMEPAD_HAPTIC_METHOD_LEFTRIGHT 1
+#define GAMEPAD_HAPTIC_METHOD_SIMPLERUMBLE 2
+
+#define GAMEPAD_HAPTIC_SIMPLE_HIFREQ_MOTOR_WEIGHT 0.33
+#define GAMEPAD_HAPTIC_SIMPLE_LOWFREQ_MOTOR_WEIGHT 0.8
+
 class SdlInputHandler
 {
 public: