iOS cocos3d cameraを端末の姿勢に合わせて制御する

ios_cocos3d_device_camera.m

#import <CoreMotion/CoreMotion.h>

-(void) initMotionManager{
    // 1.CMMotionManagereより、端末の姿勢情報を取得
    _motionManager = [[CMMotionManager alloc] init];
    // 更新の間隔を設定する
    _motionManager.deviceMotionUpdateInterval = 1.0f / 30.0f;
    
    // ハンドラを設定する
    CMDeviceMotionHandler   deviceMotionHandler;
    deviceMotionHandler = ^ (CMDeviceMotion* motion, NSError* error) {
        
        // 2.姿勢情報をx軸90度回転して適用
        CMQuaternion  quaternion  = motion.attitude.quaternion;
        CC3Vector4    camQuaternion;
        camQuaternion.w =  quaternion.w;
        camQuaternion.x = -quaternion.x;
        camQuaternion.y = -quaternion.z;
        camQuaternion.z =  quaternion.y;
        camQuaternion   = [self multiplyQuaternion:camQuaternion onAxis:CC3Vector4Make(1, 0, 0, 0) byDegress:90];
        self.activeCamera.quaternion = camQuaternion;
        // 3.landscape Rightの場合、カメラをz軸回転
        self.activeCamera.rotation = cc3v(self.activeCamera.rotation.x,
                                          self.activeCamera.rotation.y,
                                          self.activeCamera.rotation.z-90);
    };
    
    // 向きの更新通知を開始する
    [_motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue currentQueue]
                                        withHandler:deviceMotionHandler];
}

-(CC3Vector4)multiplyQuaternion:(CC3Vector4)q2 onAxis:(CC3Vector4)axis byDegress:(float)degrees{
    
    CC3Vector4 q1;
    
    q1.x = axis.x;
    q1.y = axis.y;
    q1.z = axis.z;
    
    // Converts the angle in degrees to radians.
    float radians = CC_DEGREES_TO_RADIANS(degrees);
    
    // Finds the sin and cosine for the half angle.
    float sin = sinf(radians * 0.5);
    float cos = cosf(radians * 0.5);
    
    // Formula to construct a new Quaternion based on direction and angle.
    q1.w = cos;
    q1.x = q1.x * sin;
    q1.y = q1.y * sin;
    q1.z = q1.z * sin;
    
    // Multiply quaternion, q1 x q2 is not equal to q2 x q1
    
    CC3Vector4 newQ;
    newQ.w = q1.w * q2.w - q1.x * q2.x - q1.y * q2.y - q1.z * q2.z;
    newQ.x = q1.w * q2.x + q1.x * q2.w + q1.y * q2.z - q1.z * q2.y;
    newQ.y = q1.w * q2.y - q1.x * q2.z + q1.y * q2.w + q1.z * q2.x;
    newQ.z = q1.w * q2.z + q1.x * q2.y - q1.y * q2.x + q1.z * q2.w;
    
    return  newQ;
}