"Flick Stick" controller layout implementation

With southpaw version added to "sticks layout" menu
Cvar for length of stick to be considered a flick or rotation
Lacks rotation smoothing

doc/040_cvarlist.md

@@ -476,6 +476,9 @@ Set `0` by default.
   - `2`: *Legacy*, left moves forward/backward and turns, right strafes
     and looks up/down
   - `3`: *Legacy Southpaw*, inverted sticks version of previous one
+  - `4`: *Flick Stick*, left stick moves, right checks your surroundings
+    in 360º, gyro required for looking up/down
+  - `5`: *Flick Stick Southpaw*, swapped sticks version of last one
 
 * **joy_left_deadzone** / **joy_right_deadzone**: Inner, circular
   deadzone for each stick, where inputs below this radius will be
@@ -486,13 +489,18 @@ Set `0` by default.
   deadzone with the shape of a "bowtie", which will help you to do
   perfectly horizontal or vertical movements the more you mark a
   direction with the stick. Increasing this too much will reduce speed
-  for the diagonals. Default `0.15`.
+  for the diagonals, but will help you to mark 90º/180º turns with Flick
+  Stick. Default `0.15`.
 
 * **joy_left_expo** / **joy_right_expo**: Exponents on the response
   curve on each stick. Increasing this will make small movements to
   represent much smaller inputs, which helps precision with the sticks.
   `1.0` is linear. Default `2.0` (quadratic curve).
 
+* **joy_flick_threshold**: Used only with Flick Stick, specifies the
+  distance from the center of the stick that will make the player flick
+  or rotate. Default `0.65` (65%).
+
 * **gyro_mode**: Operation mode for the gyroscope sensor of the game
   controller. Options are `0` = always off, `1` = off with the
   `+gyroaction` bind to enable, `2` = on with `+gyroaction` to

src/client/input/sdl.c

@@ -24,6 +24,9 @@
  * - http://quakespasm.sourceforge.net
  * - https://github.com/Minimuino/thumbstick-deadzones
  *
+ * Flick Stick handling is based on:
+ * http://gyrowiki.jibbsmart.com/blog:good-gyro-controls-part-2:the-flick-stick
+ *
  * =======================================================================
  *
  * This is the Quake II input system backend, implemented with SDL.
@@ -51,7 +54,9 @@ enum {
 	LAYOUT_DEFAULT			= 0,
 	LAYOUT_SOUTHPAW,
 	LAYOUT_LEGACY,
-	LAYOUT_LEGACY_SOUTHPAW
+	LAYOUT_LEGACY_SOUTHPAW,
+	LAYOUT_FLICK_STICK,
+	LAYOUT_FLICK_STICK_SOUTHPAW
 };
 
 typedef struct
@@ -142,6 +147,7 @@ static cvar_t *joy_left_deadzone;
 static cvar_t *joy_right_expo;
 static cvar_t *joy_right_snapaxis;
 static cvar_t *joy_right_deadzone;
+static cvar_t *joy_flick_threshold;
 
 // Joystick haptic
 static cvar_t *joy_haptic_magnitude;
@@ -180,6 +186,11 @@ static updates_countdown_reasons countdown_reason = REASON_CONTROLLERINIT;
 // Factor used to transform from SDL input to Q2 "view angle" change
 static float normalize_sdl_gyro = 1.0f / M_PI;	// can change depending on hardware
 
+// Flick Stick
+#define FLICK_TIME 6		// number of frames it takes for a flick to execute
+static float target_angle;	// angle to end up facing at the end of a flick
+static unsigned short int flick_progress = FLICK_TIME;
+
 extern void CalibrationFinishedCallback(void);
 
 /* ------------------------------------------------------------------ */
@@ -952,6 +963,59 @@ IN_ApplyExpo(thumbstick_t stick, float exponent)
 	return result;
 }
 
+/*
+ * Flick Stick handling: detect if the player just started one, or return the
+ * player rotation if stick was already flicked
+ */
+static float
+IN_FlickStick(thumbstick_t stick, float axial_deadzone)
+{
+	static qboolean is_flicking;
+	static float last_stick_angle;
+	thumbstick_t processed = stick;
+	float angle_change = 0;
+
+	if (IN_StickMagnitude(stick) > min(joy_flick_threshold->value, 1.0f))	// flick!
+	{
+		// Make snap-to-axis only if player wasn't already flicking
+		if (!is_flicking || flick_progress < FLICK_TIME)
+		{
+			processed = IN_SlopedAxialDeadzone(stick, axial_deadzone);
+		}
+
+		const float stick_angle = (180 / M_PI) * atan2f(-processed.x, -processed.y);
+
+		if (!is_flicking)
+		{
+			// Flicking begins now, with a new target
+			is_flicking = true;
+			flick_progress = 0;
+			target_angle = stick_angle;
+		}
+		else
+		{
+			// Was already flicking, just turning now
+			angle_change = stick_angle - last_stick_angle;
+
+			// angle wrap: https://stackoverflow.com/a/11498248/1130520
+			angle_change = fmod(angle_change + 180.0f, 360.0f);
+			if (angle_change < 0)
+			{
+				angle_change += 360.0f;
+			}
+			angle_change -= 180.0f;
+		}
+
+		last_stick_angle = stick_angle;
+	}
+	else
+	{
+		is_flicking = false;
+	}
+
+	return angle_change;
+}
+
 /*
  * Move handling
  */
@@ -961,6 +1025,12 @@ IN_Move(usercmd_t *cmd)
 	// Factor used to transform from SDL joystick input ([-32768, 32767])  to [-1, 1] range
 	static const float normalize_sdl_axis = 1.0f / 32768.0f;
 
+	// Flick Stick's factors to change to the target angle with a feeling of "ease out"
+	static const float rotation_factor[FLICK_TIME] =
+	{
+		0.305555556f, 0.249999999f, 0.194444445f, 0.138888889f, 0.083333333f, 0.027777778f
+	};
+
 	static float old_mouse_x;
 	static float old_mouse_y;
 	static float joystick_yaw, joystick_pitch;
@@ -1049,16 +1119,30 @@ IN_Move(usercmd_t *cmd)
 	if (left_stick.x || left_stick.y)
 	{
 		left_stick = IN_RadialDeadzone(left_stick, joy_left_deadzone->value);
+		if ((int)joy_layout->value == LAYOUT_FLICK_STICK_SOUTHPAW)
+		{
+			cl.viewangles[YAW] += IN_FlickStick(left_stick, joy_left_snapaxis->value);
+		}
+		else
+		{
 			left_stick = IN_SlopedAxialDeadzone(left_stick, joy_left_snapaxis->value);
 			left_stick = IN_ApplyExpo(left_stick, joy_left_expo->value);
 		}
+	}
 
 	if (right_stick.x || right_stick.y)
 	{
 		right_stick = IN_RadialDeadzone(right_stick, joy_right_deadzone->value);
+		if ((int)joy_layout->value == LAYOUT_FLICK_STICK)
+		{
+			cl.viewangles[YAW] += IN_FlickStick(right_stick, joy_right_snapaxis->value);
+		}
+		else
+		{
 			right_stick = IN_SlopedAxialDeadzone(right_stick, joy_right_snapaxis->value);
 			right_stick = IN_ApplyExpo(right_stick, joy_right_expo->value);
 		}
+	}
 
 	switch((int)joy_layout->value)
 	{
@@ -1080,6 +1164,14 @@ IN_Move(usercmd_t *cmd)
 			joystick_yaw = right_stick.x;
 			joystick_pitch = left_stick.y;
 			break;
+		case LAYOUT_FLICK_STICK:	// yaw already set by now
+			joystick_forwardmove = left_stick.y;
+			joystick_sidemove = left_stick.x;
+			break;
+		case LAYOUT_FLICK_STICK_SOUTHPAW:
+			joystick_forwardmove = right_stick.y;
+			joystick_sidemove = right_stick.x;
+			break;
 		default:	// LAYOUT_DEFAULT
 			joystick_forwardmove = left_stick.y;
 			joystick_sidemove = left_stick.x;
@@ -1129,6 +1221,13 @@ IN_Move(usercmd_t *cmd)
 	{
 		cl.viewangles[PITCH] -= (m_pitch->value * gyro_pitch) * gyroViewFactor;
 	}
+
+	// Flick Stick: flick in progress, changing the yaw angle to the target progressively
+	if (flick_progress < FLICK_TIME)
+	{
+		cl.viewangles[YAW] += target_angle * rotation_factor[flick_progress];
+		flick_progress++;
+	}
 }
 
 /* ------------------------------------------------------------------ */
@@ -1664,6 +1763,7 @@ IN_Init(void)
 	joy_right_expo = Cvar_Get("joy_right_expo", "2.0", CVAR_ARCHIVE);
 	joy_right_snapaxis = Cvar_Get("joy_right_snapaxis", "0.15", CVAR_ARCHIVE);
 	joy_right_deadzone = Cvar_Get("joy_right_deadzone", "0.16", CVAR_ARCHIVE);
+	joy_flick_threshold = Cvar_Get("joy_flick_threshold", "0.65", CVAR_ARCHIVE);
 
 	gyro_calibration_x = Cvar_Get("gyro_calibration_x", "0.0", CVAR_ARCHIVE);
 	gyro_calibration_y = Cvar_Get("gyro_calibration_y", "0.0", CVAR_ARCHIVE);

src/client/menu/menu.c

@@ -1814,6 +1814,17 @@ Joy_MenuInit(void)
         0
     };
 
+    static const char *stick_layouts_fs[] =
+    {
+        "default",
+        "southpaw",
+        "legacy",
+        "legacy southpaw",
+        "flick stick",
+        "flick stick spaw",
+        0
+    };
+
     int y = 0;
 
     s_joy_menu.x = (int)(viddef.width * 0.50f);
@@ -1905,8 +1916,16 @@ Joy_MenuInit(void)
     y += 10;
     s_joy_layout_box.generic.name = "stick layout";
     s_joy_layout_box.generic.callback = StickLayoutFunc;
+    if (gyro_hardware || joy_layout->value > 3)
+    {
+        s_joy_layout_box.itemnames = stick_layouts_fs;
+        s_joy_layout_box.curvalue = ClampCvar(0, 5, joy_layout->value);
+    }
+    else
+    {
         s_joy_layout_box.itemnames = stick_layouts;
         s_joy_layout_box.curvalue = ClampCvar(0, 3, joy_layout->value);
+    }
     Menu_AddItem(&s_joy_menu, (void *)&s_joy_layout_box);
 
     if (gyro_hardware)