From c5b74947a0f85c2cababf790e02ed781eb48e557 Mon Sep 17 00:00:00 2001
From: Jools Wills <buzz@exotica.org.uk>
Date: Sat, 13 Aug 2016 01:40:50 +0100
Subject: [PATCH] workaround for analogue trigger configuration - eg with xpad.

Unlike other axis, they don't default to 0, but instead start at -32768 and go to +32767 when pressed. This confuses the
current ES code axis code. As a workaround, we get the initial value and if it is -32767, we add 32767 and divide by two. This gives it
a range that can be handled with the current code (from 0 to 32767). Note on my X11 machine, I had to plug the joystick in after ES
was loaded or it get 0 as the initial axis value for the triggers. This seems ok on the RPI though, so possible some SDL issue.

With this change on a 360 controller the triggers should be correctly detected as +2 and +5 without seeing two presses for each trigger press.
---
 es-core/src/InputManager.cpp | 24 +++++++++++++++++++-----
 es-core/src/InputManager.h   |  1 +
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/es-core/src/InputManager.cpp b/es-core/src/InputManager.cpp
index f03fbc14e..c1d2db5a9 100644
--- a/es-core/src/InputManager.cpp
+++ b/es-core/src/InputManager.cpp
@@ -89,7 +89,14 @@ void InputManager::addJoystickByDeviceIndex(int id)
 	// set up the prevAxisValues
 	int numAxes = SDL_JoystickNumAxes(joy);
 	mPrevAxisValues[joyId] = new int[numAxes];
-	std::fill(mPrevAxisValues[joyId], mPrevAxisValues[joyId] + numAxes, 0); //initialize array to 0
+	mInitAxisValues[joyId] = new int[numAxes];
+
+	int axis;
+	for (int i = 0; i< numAxes; i++) {
+		axis = SDL_JoystickGetAxis(joy, i);
+		mInitAxisValues[joyId][i] = axis;
+		mPrevAxisValues[joyId][i] = axis;
+	}
 }
 
 void InputManager::removeJoystickByJoystickID(SDL_JoystickID joyId)
@@ -170,21 +177,28 @@ InputConfig* InputManager::getInputConfigByDevice(int device)
 bool InputManager::parseEvent(const SDL_Event& ev, Window* window)
 {
 	bool causedEvent = false;
+	int axis;
+	int deadzone = DEADZONE;
 	switch(ev.type)
 	{
 	case SDL_JOYAXISMOTION:
+		axis = ev.jaxis.value;
+		if (mInitAxisValues[ev.jaxis.which][ev.jaxis.axis] == -32768)
+		{
+			deadzone /= 2;
+			axis = (axis + 32767) / 2;
+		}
 		//if it switched boundaries
-		if((abs(ev.jaxis.value) > DEADZONE) != (abs(mPrevAxisValues[ev.jaxis.which][ev.jaxis.axis]) > DEADZONE))
+		if((abs(axis) > deadzone) != (abs(mPrevAxisValues[ev.jaxis.which][ev.jaxis.axis]) > deadzone))
 		{
 			int normValue;
-			if(abs(ev.jaxis.value) <= DEADZONE)
+			if(abs(axis) <= deadzone)
 				normValue = 0;
 			else
-				if(ev.jaxis.value > 0)
+				if(axis > 0)
 					normValue = 1;
 				else
 					normValue = -1;
-
 			window->input(getInputConfigByDevice(ev.jaxis.which), Input(ev.jaxis.which, TYPE_AXIS, ev.jaxis.axis, normValue, false));
 			causedEvent = true;
 		}
diff --git a/es-core/src/InputManager.h b/es-core/src/InputManager.h
index 740835634..295fa87f7 100644
--- a/es-core/src/InputManager.h
+++ b/es-core/src/InputManager.h
@@ -26,6 +26,7 @@ private:
 	InputConfig* mKeyboardInputConfig;
 
 	std::map<SDL_JoystickID, int*> mPrevAxisValues;
+	std::map<SDL_JoystickID, int*> mInitAxisValues;
 
 	bool initialized() const;