Add inversion option for joystick axes

Note that the 'invert' helper function returns int16_t instead of int32_t because it's used *after* the long value rescaling, and the max value used by the output data is int16

Author: dmadison

src/XInput.cpp

@@ -277,11 +277,12 @@ void XInputController::setJoystick(XInputControl joy, int32_t x, int32_t y) {
 	setJoystickDirect(joy, x, y);
 }
 
-void XInputController::setJoystickX(XInputControl joy, int32_t x) {
+void XInputController::setJoystickX(XInputControl joy, int32_t x, boolean invert) {
 	const XInputMap_Joystick * joyData = getJoyFromEnum(joy);
 	if (joyData == nullptr) return;  // Not a joystick
 
 	x = rescaleInput(x, *getRangeFromEnum(joy), XInputMap_Joystick::range);
+	if (invert) x = invertInput(x, XInputMap_Joystick::range);
 
 	if (getJoystickX(joy) == x) return;  // Axis hasn't changed
 
@@ -292,11 +293,12 @@ void XInputController::setJoystickX(XInputControl joy, int32_t x) {
 	autosend();
 }
 
-void XInputController::setJoystickY(XInputControl joy, int32_t y) {
+void XInputController::setJoystickY(XInputControl joy, int32_t y, boolean invert) {
 	const XInputMap_Joystick * joyData = getJoyFromEnum(joy);
 	if (joyData == nullptr) return;  // Not a joystick
 
 	y = rescaleInput(y, *getRangeFromEnum(joy), XInputMap_Joystick::range);
+	if (invert) y = invertInput(y, XInputMap_Joystick::range);
 
 	if (getJoystickY(joy) == y) return;  // Axis hasn't changed
 
@@ -521,6 +523,10 @@ int32_t XInputController::rescaleInput(int32_t val, const Range& in, const Range
 	return map(val, in.min, in.max, out.min, out.max);
 }
 
+int16_t XInputController::invertInput(int16_t val, const Range& range) {
+	return range.max - val + range.min;
+}
+
 void XInputController::setTriggerRange(int32_t rangeMin, int32_t rangeMax) {
 	setRange(TRIGGER_LEFT, rangeMin, rangeMax);
 	setRange(TRIGGER_RIGHT, rangeMin, rangeMax);

src/XInput.h

@@ -91,8 +91,8 @@ class XInputController {
 	void setTrigger(XInputControl trigger, int32_t val);
 
 	void setJoystick(XInputControl joy, int32_t x, int32_t y);
-	void setJoystickX(XInputControl joy, int32_t x);
-	void setJoystickY(XInputControl joy, int32_t y);
+	void setJoystickX(XInputControl joy, int32_t x, boolean invert=false);
+	void setJoystickY(XInputControl joy, int32_t y, boolean invert=false);
 	void setJoystick(XInputControl joy, boolean up, boolean down, boolean left, boolean right, boolean useSOCD=true);
 
 	void releaseAll();
@@ -162,6 +162,7 @@ class XInputController {
 	Range rangeTrigLeft, rangeTrigRight, rangeJoyLeft, rangeJoyRight;
 	Range * getRangeFromEnum(XInputControl ctrl);
 	static int32_t rescaleInput(int32_t val, const Range& in, const Range &out);
+	static int16_t invertInput(int16_t val, const Range& range);
 };
 
 extern XInputController XInput;