從CoreMotion姿態的rotationMatrix隔離並移除水平旋轉

Question

我正在制作類似增強現實的應用程序，其中有一個OpenGL場景，無論iOS設備如何移動，我都希望與重力保持一致。 我以為我已經使用CMDeviceMotion.attitude.pitch進行了很好的設置，直到我發現將iPhone側面傾斜會弄亂那個數字。 因此，我從pARk *示例中獲取了一些代碼，現在我試圖隔離圍繞垂直訪問的旋轉。 我正在繪制的場景並不關心用戶面對的是哪個方向，這些圖形將始終被繪制為與觀看者相距設定的距離。 我認為當我計算出垂直軸旋轉分量時，我可以將其反轉並將其乘以旋轉矩陣，以便在用戶更改航向時保持OpenGL圖形靜止不動。

這是我的代碼：

CMDeviceMotion *d = motionManager.deviceMotion;
if (d != nil) {

    CMRotationMatrix r = d.attitude.rotationMatrix;
    transformFromCMRotationMatrix(cameraTransform, &r);


    mat4f_t projectionCameraTransform;
    multiplyMatrixAndMatrix(projectionCameraTransform, projectionTransform, cameraTransform);

    GLKMatrix4 rotMatrix = GLKMatrix4Make(projectionCameraTransform[0], 
                                          projectionCameraTransform[1], 
                                          projectionCameraTransform[2], 
                                          projectionCameraTransform[3], 
                                          projectionCameraTransform[4], 
                                          projectionCameraTransform[5], 
                                          projectionCameraTransform[6], 
                                          projectionCameraTransform[7], 
                                          projectionCameraTransform[8], 
                                          projectionCameraTransform[9], 
                                          projectionCameraTransform[10], 
                                          projectionCameraTransform[11], 
                                          projectionCameraTransform[12], 
                                          projectionCameraTransform[13], 
                                          projectionCameraTransform[14], 
                                          projectionCameraTransform[15]);

    }

然后，像往常一樣在OpenGL中使用rotMatrix。

有想法，建議嗎？ 提前致謝。

* pARk示例代碼在真實空間中設置了一些點，計算出用戶的位置和這些點的相對方向，並將其繪制在屏幕上，從而使外觀看起來像漂浮在指向其位置的地平​​線上。

Answer 1

我只是根據設備屏幕的方向繞Z軸旋轉方向。 這不是最漂亮的，但它似乎可以完全滿足我的需要，而無需回頭（從而避免了健身房鎖定問題）

GLKMatrix4 deviceMotionAttitudeMatrix;
if (_cmMotionmanager.deviceMotionActive) {
    CMDeviceMotion *deviceMotion = _cmMotionmanager.deviceMotion;

    // Correct for the rotation matrix not including the screen orientation:
    // TODO: Let the device notify me when the orientation changes instead of querying on each update.
    UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];
    float deviceOrientationRadians = 0.0f;
    if (orientation == UIDeviceOrientationLandscapeLeft) {
        deviceOrientationRadians = M_PI_2;
    }
    if (orientation == UIDeviceOrientationLandscapeRight) {
        deviceOrientationRadians = -M_PI_2;
    }
    if (orientation == UIDeviceOrientationPortraitUpsideDown) {
        deviceOrientationRadians = M_PI;
    }
    GLKMatrix4 baseRotation = GLKMatrix4MakeRotation(deviceOrientationRadians, 0.0f, 0.0f, 1.0f);

    CMRotationMatrix a = deviceMotion.attitude.rotationMatrix;
    deviceMotionAttitudeMatrix
        = GLKMatrix4Make(a.m11, a.m21, a.m31, 0.0f,
                         a.m12, a.m22, a.m32, 0.0f,
                         a.m13, a.m23, a.m33, 0.0f,
                         0.0f, 0.0f, 0.0f, 1.0f);
    deviceMotionAttitudeMatrix = GLKMatrix4Multiply(baseRotation, deviceMotionAttitudeMatrix);
}
else
{
    // Look straight forward (we're probably in the simulator, or a device without a gyro)
    deviceMotionAttitudeMatrix = GLKMatrix4MakeRotation(-M_PI_2, 1.0f, 0.0f, 0.0f);
}

Answer 2

這是一些代碼來闡明如何使用titude.rotationMatrix

// initial model view matrix
GLKMatrix4 modelViewMatrix = GLKMatrix4MakeTranslation(0.0f, 0.0f, -5.f);

// convert CMRotationMatrix to GLKMatrix4
CMRotationMatrix r = motion.attitude.rotationMatrix;
GLKMatrix4 = GLKMatrix4Make(r.m11, r.m21, r.m31, 0.0f,
                            r.m12, r.m22, r.m32, 0.0f,
                            r.m13, r.m23, r.m33, 0.0f,
                             0.0f,  0.0f,  0.0f, 1.0f);

// apply motion rotation matrix
modelViewMatrix = GLKMatrix4Multiply(modelViewMatrix, _motionRotationMatrix);

// apply matrix to effect
self.effect.transform.modelviewMatrix = modelViewMatrix;

Answer 3

我從這個答案中得到了一些提示，並提出了一個解決方案：

https://stackoverflow.com/questions/5328848/simulating-an-image-floating-effect-using-coremotion-devicemotion-on-the-iphone/5442962#5442962

if (d != nil) {

    GLKMatrix4 rotMatrix = GLKMatrix4MakeRotation(0, 0, 1, 0);
    float pitch = d.attitude.pitch;

    if (d.gravity.z > 0)
        pitch = -pitch;

    rotMatrix = GLKMatrix4Rotate(rotMatrix, pitch, -1, 0, 0);
    rotMatrix = GLKMatrix4Rotate(rotMatrix, d.attitude.roll, 0, -1, 0);
    rotMatrix = GLKMatrix4Rotate(rotMatrix, d.attitude.yaw, 0, 0, -1);
    rotMatrix = GLKMatrix4Multiply(rotMatrix, GLKMatrix4MakeRotation(M_PI/2, 1, 0, 0));
}

但是，當手機接近垂直時，此雜草叢生。 所以我還在找。