iOS: Feed the gyroscope into tilt input

Same as Android: rotation rates go to NativeGyroscope, and SYSPROP_HAS_GYRO shows the "Use gyroscope" option.

Accelerometer data is now scaled from g to m/s^2, like Android's. Tilt normalizes it, but the gyro fusion only trusts the accelerometer when it reads about 9.81, so in g it would never correct drift.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Common/System/NativeApp.h

@@ -66,6 +66,7 @@ void NativeResized();
 void NativeTouch(const TouchInput &touch);
 bool NativeKey(const KeyInput &key);
 void NativeAxis(const AxisInput *axis, size_t count);
+// In m/s^2, the way Android reports it: about +9.81 on z with the device lying screen up.
 void NativeAccelerometer(float tiltX, float tiltY, float tiltZ);
 // Angular rates in rad/s around the NativeAccelerometer axes. The timestamp is in seconds, on any clock (only deltas are used).
 void NativeGyroscope(float x, float y, float z, double timestamp);

ios/Controls.h

@@ -34,6 +34,7 @@ private:
 
 #if !PPSSPP_PLATFORM(TVOS)
 void ProcessAccelerometerData(CMAccelerometerData *accData);
+void ProcessGyroData(CMGyroData *gyroData);
 #endif
 InputKeyCode HIDUsageToInputKeyCode(UIKeyboardHIDUsage usage);
 

ios/Controls.mm

@@ -385,8 +385,16 @@ void ProcessAccelerometerData(CMAccelerometerData *accData) {
 	CMAcceleration acc = accData.acceleration;
 	// INFO_LOG(SYSTEM, "%f %f %f", acc.x, acc.y, acc.z);
 
+	// Core Motion reports acceleration in g, with the opposite sign of Android's m/s^2.
 	// Might need to change these for portrait or inverse landscape
-	NativeAccelerometer(-acc.x, -acc.y, -acc.z);
+	const float standardGravity = 9.81f;
+	NativeAccelerometer(-acc.x * standardGravity, -acc.y * standardGravity, -acc.z * standardGravity);
+}
+
+void ProcessGyroData(CMGyroData *gyroData) {
+	// Same axes and units (rad/s, right-handed) as Android.
+	CMRotationRate rate = gyroData.rotationRate;
+	NativeGyroscope(rate.x, rate.y, rate.z, gyroData.timestamp);
 }
 #endif
 

ios/ViewController.mm

@@ -312,6 +312,21 @@ static int GetPickerRequestId(id picker) {
 	} else {
 		INFO_LOG(Log::G3D, "No accelerometer available, not starting updates.");
 	}
+
+	if (self.motionManager.gyroAvailable) {
+		self.motionManager.gyroUpdateInterval = 1.0 / 60.0;
+		INFO_LOG(Log::G3D, "Starting gyro updates.");
+
+		// Same serial queue as the accelerometer, so the two don't race in the tilt fusion.
+		[self.motionManager startGyroUpdatesToQueue:self.accelerometerQueue
+							withHandler:^(CMGyroData *gyroData, NSError *error) {
+			if (error) {
+				NSLog(@"Gyro error: %@", error);
+				return;
+			}
+			ProcessGyroData(gyroData);
+		}];
+	}
 #endif
 
 	// Spin up the render thread, which in turn starts the emu thread.
@@ -328,6 +343,10 @@ static int GetPickerRequestId(id picker) {
 		INFO_LOG(Log::G3D, "Stopping accelerometer updates");
 		[self.motionManager stopAccelerometerUpdates];
 	}
+	if (self.motionManager.gyroActive) {
+		INFO_LOG(Log::G3D, "Stopping gyro updates");
+		[self.motionManager stopGyroUpdates];
+	}
 #endif
 }
 

ios/main.mm

@@ -41,6 +41,10 @@
 #include "Common/Log/LogManager.h"
 #include "Core/Util/DarwinFileSystemServices.h"
 
+#if !PPSSPP_PLATFORM(TVOS)
+#import <CoreMotion/CoreMotion.h>
+#endif
+
 // Compile out all the hackery in app store builds. tvOS doesn't have posix_spawn, and there's no
 // jailbreak scene to speak of.
 #if !PPSSPP_PLATFORM(IOS_APP_STORE) && !PPSSPP_PLATFORM(TVOS)
@@ -324,6 +328,7 @@ bool System_GetPropertyBool(SystemProperty prop) {
 	case SYSPROP_HAS_FOLDER_BROWSER:
 	case SYSPROP_HAS_IMAGE_BROWSER:
 	case SYSPROP_HAS_ACCELEROMETER:
+	case SYSPROP_HAS_GYRO:
 	case SYSPROP_HAS_KEYBOARD:
 	case SYSPROP_KEYBOARD_IS_SOFT:
 	case SYSPROP_SUPPORTS_SHARE_TEXT:
@@ -363,6 +368,13 @@ bool System_GetPropertyBool(SystemProperty prop) {
 			return false;
 		case SYSPROP_HAS_ACCELEROMETER:
 			return true;
+#if !PPSSPP_PLATFORM(TVOS)
+		case SYSPROP_HAS_GYRO:
+		{
+			static const bool hasGyro = [[CMMotionManager alloc] init].gyroAvailable;
+			return hasGyro;
+		}
+#endif
 		case SYSPROP_HAS_KEYBOARD:
 			return true;
 		case SYSPROP_SUPPORTS_SHARE_TEXT: