[英]Yaw range on iPhone 5s
我正在使用CMDeviceMotion和姿態的四元數來獲取俯仰和偏航值,然后將其應用於Cocos3D場景中的CC3Camera來旋轉攝像機。
#define RadiansToDegrees(x) ((180 / M_PI) * x)
- (void)initializeScene
{
//...
CC3Camera *cam = [CC3Camera nodeWithName:@"Camera"];
cam.location = cc3v(0, 10, 0.0001);
cam.targetLocation = cc3v(0, 0, 0);
_cameraBoom = [CC3Node nodeWithName:@"CameraBoom"];
_cameraBoom.location = cc3v(0, 0, 0);
[_cameraBoom addChild:cam];
[self addChild:_cameraBoom];
[self setActiveCamera:cam];
_cameraBoom.rotation = cc3v(0, 90, 0);
//...
_motionManager = [[CMMotionManager alloc] init];
_referenceAttitude = nil;
_initialCameraRotation = _cameraBoom.rotation;
[self enableMotion];
}
- (void)enableMotion
{
CMDeviceMotion *deviceMotion = _motionManager.deviceMotion;
_referenceAttitude = deviceMotion.attitude;
_initialCameraRotation = _cameraBoom.rotation;
[_motionManager startDeviceMotionUpdates];
if (!_gyroTimer) {
_gyroTimer = [NSTimer scheduledTimerWithTimeInterval:1 / 30.0
target:self
selector:@selector(doGyroUpdate)
userInfo:nil
repeats:YES];
}
}
- (void)doGyroUpdate
{
CMDeviceMotion *deviceMotion = _motionManager.deviceMotion;
CMAttitude *attitude = deviceMotion.attitude;
if (_referenceAttitude != nil) {
[attitude multiplyByInverseOfAttitude:_referenceAttitude];
}
CMQuaternion quat = attitude.quaternion;
double pitch = RadiansToDegrees(atan2(2 * (quat.x * quat.w + quat.y * quat.z), 1 - 2 * (quat.x * quat.x + quat.z * quat.z)));
double yaw = RadiansToDegrees(asin(2 * (quat.x * quat.y + quat.w * quat.z)));
_cameraBoom.rotation = CC3VectorAdd(_initialCameraRotation, cc3v(pitch, yaw, 0));
}
節距在[-π,π]范圍內。 當設備面朝上時,俯仰= 0,當我從桌子上拿下設備並指向它拍照時,它變為π/ 2(人像模式)。 [-π,π]范圍使我可以將設備旋轉360°。 當面朝下(即設備朝下)時,音高值為π。
偏航范圍僅為[-π/ 2,π/ 2]。 當我將設備向左旋轉時,它從0開始,到π/ 2。 但是,如果我將其旋轉超過π/ 2,則偏航值開始減小。
是否可以像俯仰一樣獲得[-π,π]范圍內的偏航值? 能夠將攝像機側向旋轉180°(向左和向右,以獲得完整的360°視角),而不是垂直翻轉設備以向后看攝像機,這將更加有用。
最終,我使用內置功能來完成此操作:
- (void)doGyroUpdate
{
CMDeviceMotion *deviceMotion = _motionManager.deviceMotion;
CMAttitude *attitude = deviceMotion.attitude;
if (_referenceAttitude != nil) {
[attitude multiplyByInverseOfAttitude:_referenceAttitude];
}
CMQuaternion quat = attitude.quaternion;
CC3Quaternion cc3Quat = CC3QuaternionMake(quat.x, quat.y, quat.z, quat.w);
CC3Vector rot = CC3RotationFromQuaternion(cc3Quat);
_cameraBoom.rotation = cc3v(-rot.x, -rot.z, rot.y);
}
結果:
像這樣旋轉相機可以讓您環顧四周的天空盒,就像通常通過設備的后置相機環顧世界一樣。 我CC3Camera對象是映射給它的HDRI圖像,在里面一球內(見這個職位)。
平穩旋轉相機:
[_cameraBoom runAction:[CC3ActionRotateTo actionWithDuration:0.15 rotateTo:cc3v(-rot.x, -rot.z, rot.y)]];
希望這也能幫助其他人。
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