Add gyro jitter suppression

Controlled by new cvar `gyro_noise_thresh`, defaulting to 1.5 (degrees per second).

Note: samples above this threshold are unchanged (no input delay).

Quake/in_sdl.c

@@ -75,6 +75,8 @@ cvar_t gyro_calibration_x = {"gyro_calibration_x", "0", CVAR_ARCHIVE};
 cvar_t gyro_calibration_y = {"gyro_calibration_y", "0", CVAR_ARCHIVE};
 cvar_t gyro_calibration_z = {"gyro_calibration_z", "0", CVAR_ARCHIVE};
 
+cvar_t gyro_noise_thresh = {"gyro_noise_thresh", "1.5", CVAR_ARCHIVE};
+
 static SDL_JoystickID joy_active_instaceid = -1;
 static SDL_GameController *joy_active_controller = NULL;
 
@@ -447,6 +449,7 @@ void IN_Init (void)
 	Cvar_RegisterVariable(&gyro_calibration_x);
 	Cvar_RegisterVariable(&gyro_calibration_y);
 	Cvar_RegisterVariable(&gyro_calibration_z);
+	Cvar_RegisterVariable(&gyro_noise_thresh);
 
 	Cmd_AddCommand ("+gyroaction", IN_GyroActionDown);
 	Cmd_AddCommand ("-gyroaction", IN_GyroActionUp);
@@ -1103,6 +1106,18 @@ qboolean IN_IsCalibratingGyro (void)
 	return updates_countdown != 0;
 }
 
+static float IN_FilterGyroSample (float prev, float cur)
+{
+	float thresh = DEG2RAD (gyro_noise_thresh.value);
+	float d = fabs (cur - prev);
+	if (d < thresh)
+	{
+		d /= thresh;
+		cur = LERP (prev, cur, 0.01f + 0.99f * d * d);
+	}
+	return cur;
+}
+
 void IN_SendKeyEvents (void)
 {
 	SDL_Event event;
@@ -1211,15 +1226,17 @@ void IN_SendKeyEvents (void)
 			}
 			if (gyro_active && gyro_mode.value)
 			{
+				float prev_yaw = gyro_yaw;
+				float prev_pitch = gyro_pitch;
+
 				if (!gyro_turning_axis.value)
-				{
 					gyro_yaw = event.csensor.data[1] - gyro_calibration_y.value; // yaw
-				}
 				else
-				{
 					gyro_yaw = -(event.csensor.data[2] - gyro_calibration_z.value); // roll
-				}
 				gyro_pitch = event.csensor.data[0] - gyro_calibration_x.value;
+
+				gyro_yaw = IN_FilterGyroSample (prev_yaw, gyro_yaw);
+				gyro_pitch = IN_FilterGyroSample (prev_pitch, gyro_pitch);
 			}
 			else
 			{

Quake/menu.c

@@ -71,6 +71,7 @@ extern cvar_t gyro_mode;
 extern cvar_t gyro_turning_axis;
 extern cvar_t gyro_pitchsensitivity;
 extern cvar_t gyro_yawsensitivity;
+extern cvar_t gyro_noise_thresh;
 
 extern char crosshair_char;
 
@@ -3164,6 +3165,8 @@ void M_Calibration_Key (int key)
 #define MAX_TRIGGER_DEADZONE	0.75f
 #define MIN_GYRO_SENS			0.1f
 #define MAX_GYRO_SENS			8.f
+#define MIN_GYRO_NOISE_THRESH	0.f
+#define MAX_GYRO_NOISE_THRESH	5.f
 
 /*
 ================
@@ -3267,6 +3270,7 @@ void M_Menu_Gamepad_f (void)
 	def(GPAD_OPT_GYROAXIS,		"Gyro Axis")		\
 	def(GPAD_OPT_GYROSENSX,		"Gyro Yaw Speed")	\
 	def(GPAD_OPT_GYROSENSY,		"Gyro Pitch Speed")	\
+	def(GPAD_OPT_GYRONOISE,		"Gyro Noise Thresh")\
 	def(GPAD_OPT_CALIBRATE,		"Calibrate")		\
 ////////////////////////////////////////////////////
 
@@ -3761,6 +3765,9 @@ void M_AdjustSliders (int dir)
 	case GPAD_OPT_GYROSENSY:
 		Cvar_SetValueQuick (&gyro_pitchsensitivity, CLAMP (MIN_GYRO_SENS, gyro_pitchsensitivity.value + dir * .1f, MAX_GYRO_SENS));
 		break;
+	case GPAD_OPT_GYRONOISE:
+		Cvar_SetValueQuick (&gyro_noise_thresh, CLAMP (MIN_GYRO_NOISE_THRESH, gyro_noise_thresh.value + dir * .5f, MAX_GYRO_NOISE_THRESH));
+		break;
 	case GPAD_OPT_CALIBRATE:
 		M_Menu_Calibration_f ();
 		break;
@@ -3888,6 +3895,10 @@ qboolean M_SetSliderValue (int option, float f)
 		f = LERP (MIN_GYRO_SENS, MAX_GYRO_SENS, f);
 		Cvar_SetValueQuick (&gyro_pitchsensitivity, f);
 		return true;
+	case GPAD_OPT_GYRONOISE:
+		f = LERP (MIN_GYRO_NOISE_THRESH, MAX_GYRO_NOISE_THRESH, f);
+		Cvar_SetValueQuick (&gyro_noise_thresh, f);
+		return true;
 	default:
 		return false;
 	}
@@ -4203,6 +4214,10 @@ static void M_Options_DrawItem (int y, int item)
 		r = (gyro_pitchsensitivity.value - MIN_GYRO_SENS) / (MAX_GYRO_SENS - MIN_GYRO_SENS);
 		M_DrawSlider (x, y, r);
 		break;
+	case GPAD_OPT_GYRONOISE:
+		r = (gyro_noise_thresh.value - MIN_GYRO_NOISE_THRESH) / (MAX_GYRO_NOISE_THRESH - MIN_GYRO_NOISE_THRESH);
+		M_DrawSlider (x, y, r);
+		break;
 
 	default:
 		break;