Use the gyroscope to look around on Android

demo/android/app/src/main/java/graphics/pathfinder/pathfinderdemo/PathfinderActivity.java

@@ -2,7 +2,12 @@ package graphics.pathfinder.pathfinderdemo;
 
 import android.Manifest;
 import android.annotation.SuppressLint;
+import android.content.Context;
 import android.content.pm.PackageManager;
+import android.hardware.Sensor;
+import android.hardware.SensorEvent;
+import android.hardware.SensorEventListener;
+import android.hardware.SensorManager;
 import android.support.annotation.NonNull;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.content.ContextCompat;
@@ -14,6 +19,9 @@ import android.util.Log;
 import android.view.MotionEvent;
 import android.view.View;
 
+import java.util.ArrayList;
+import java.util.Arrays;
+
 /**
  * An example full-screen activity that shows and hides the system UI (i.e.
  * status bar and navigation/system bar) with user interaction.
@@ -154,6 +162,42 @@ public class PathfinderActivity extends AppCompatActivity {
                 return true;
             }
         });
+
+        final SensorManager sensorManager = (SensorManager)
+                getSystemService(Context.SENSOR_SERVICE);
+        final Sensor rotationSensor = sensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR);
+        sensorManager.registerListener(new SensorEventListener() {
+            private boolean mInitialized;
+            private float mPitch;
+            private float mYaw;
+
+            @Override
+            public void onSensorChanged(SensorEvent event) {
+                // https://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles#Quaternion_to_Euler_Angles_Conversion
+                float[] q = event.values;
+                float pitch = (float)Math.asin(2.0 * (q[0] * q[2] - q[3] * q[1]));
+                float yaw = (float)Math.atan2(2.0 * (q[0] * q[3] + q[1] * q[2]),
+                                              1.0 - 2.0 * (q[2] * q[2] + q[3] * q[3]));
+
+                float deltaPitch = pitch - mPitch;
+                float deltaYaw = yaw - mYaw;
+
+                mPitch = pitch;
+                mYaw = yaw;
+
+                if (!mInitialized) {
+                    mInitialized = true;
+                    return;
+                }
+
+                PathfinderDemoRenderer.pushLookEvent(-deltaPitch, deltaYaw);
+            }
+
+            @Override
+            public void onAccuracyChanged(Sensor sensor, int accuracy) {
+
+            }
+        }, rotationSensor, 5000);
     }
 
     @Override

demo/android/app/src/main/java/graphics/pathfinder/pathfinderdemo/PathfinderDemoRenderer.java

@@ -14,6 +14,7 @@ public class PathfinderDemoRenderer extends Object implements GLSurfaceView.Rend
 
     public static native void pushMouseDownEvent(int x, int y);
     public static native void pushMouseDraggedEvent(int x, int y);
+    public static native void pushLookEvent(float pitch, float yaw);
 
     static {
         System.loadLibrary("pathfinder_android_demo");

demo/android/rust/src/lib.rs

@@ -19,7 +19,6 @@ use pathfinder_geometry::basic::point::Point2DI32;
 use pathfinder_gl::GLVersion;
 use pathfinder_gpu::resources::ResourceLoader;
 use std::cell::RefCell;
-use std::ffi::CString;
 use std::io::Error as IOError;
 use std::mem;
 use std::os::raw::c_void;
@@ -63,8 +62,8 @@ pub unsafe extern "system" fn
 #[no_mangle]
 pub unsafe extern "system" fn
         Java_graphics_pathfinder_pathfinderdemo_PathfinderDemoRenderer_pushMouseDownEvent(
-            env: JNIEnv,
-            class: JClass,
+            _: JNIEnv,
+            _: JClass,
             x: i32,
             y: i32) {
     EVENT_QUEUE.lock().unwrap().push(Event::MouseDown(Point2DI32::new(x, y)))
@@ -73,13 +72,23 @@ pub unsafe extern "system" fn
 #[no_mangle]
 pub unsafe extern "system" fn
         Java_graphics_pathfinder_pathfinderdemo_PathfinderDemoRenderer_pushMouseDraggedEvent(
-            env: JNIEnv,
-            class: JClass,
+            _: JNIEnv,
+            _: JClass,
             x: i32,
             y: i32) {
     EVENT_QUEUE.lock().unwrap().push(Event::MouseDragged(Point2DI32::new(x, y)))
 }
 
+#[no_mangle]
+pub unsafe extern "system" fn
+        Java_graphics_pathfinder_pathfinderdemo_PathfinderDemoRenderer_pushLookEvent(
+            _: JNIEnv,
+            _: JClass,
+            pitch: f32,
+            yaw: f32) {
+    EVENT_QUEUE.lock().unwrap().push(Event::Look { pitch, yaw })
+}
+
 struct WindowImpl;
 
 impl Window for WindowImpl {

demo/common/src/lib.rs

@@ -275,6 +275,12 @@ impl<W> DemoApp<W> where W: Window {
                         *transform = transform.post_translate(position);
                     }
                 }
+                Event::Look { pitch, yaw } => {
+                    if let Camera::ThreeD { ref mut transform, .. } = self.camera {
+                        transform.pitch += pitch;
+                        transform.yaw += yaw;
+                    }
+                }
                 Event::KeyDown(Keycode::Alphanumeric(b'w')) => {
                     if let Camera::ThreeD { ref mut velocity, .. } = self.camera {
                         let scale_factor = scale_factor_for_view_box(self.scene_view_box);

demo/common/src/window.rs

@@ -39,6 +39,7 @@ pub enum Event {
     MouseMoved(Point2DI32),
     MouseDragged(Point2DI32),
     Zoom(f32),
+    Look { pitch: f32, yaw: f32 },
     User { message_type: u32, message_data: u32 },
 }