I'm rotating a UIView based on the accelerometer data, and it works fine except that the UIView is deformed. I'm not sure how to fix the issue. Here's the code in my didAccelerate method:
float kFilteringFactor = 0.175;
CGFloat x = acceleration.x * kFilteringFactor + acceleration.x * (1.0 - kFilteringFactor);
CGFloat y = acceleration.y * kFilteringFactor + acceleration.y * (1.0 - kFilteringFactor);
float radians = M_PI - atan2(y, x);
[_horizonView setTransform:CGAffineTransformMakeRotation(radians)];
Am I performing the rotation incorrectly? I've changed the origin point in Xcode, but that appears to have no effect.
what kind of deformation occures? I think the the rotation is fine.
Related
I am searching for a good and fluid way to move multiple UIViews over the Screen at once. The Action should happen when the Accelerometer detects acceleration. I have already tried this way:
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{
CGPoint ObjectPos = Object.center;
ObjectPos.x -= acceleration.x;
Object.center = ObjectPos;
}
(of course I added some tweaking to improve the movement detection), but all in all, it still is not very fluid.
I hoped there is some way with core animation, but it does not seem to work with the acceleration pretty well.
Help is really appreciated, thanks!
I advise you to read this piece of documentation: Isolating the Gravity Component from Acceleration Data and the section below that called 'Isolating Instantaneous Motion from Acceleration Data'.
Basically, you need to filter out gravity in order to get smooth movement. The link provides sample-code.
Edit: UIAccelerometer was deprecated in iOS 5.0, and the accompanying documentation seems to be gone as well.
For future reference I did some digging and found, what seems to be, a 'carbon copy' of the original sample code (source):
// This example uses a low-value filtering factor to generate a value that uses 10 percent of the
// unfiltered acceleration data and 90 percent of the previously filtered value
// Isolating the effects of gravity from accelerometer data
#define kFilteringFactor 0.1
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
// Use a basic low-pass filter to keep only the gravity component of each axis.
accelX = (acceleration.x * kFilteringFactor) + (accelX * (1.0 - kFilteringFactor));
accelY = (acceleration.y * kFilteringFactor) + (accelY * (1.0 - kFilteringFactor));
accelZ = (acceleration.z * kFilteringFactor) + (accelZ * (1.0 - kFilteringFactor));
// Use the acceleration data.
}
// shows a simplified high-pass filter computation with constant effect of gravity.
// Getting the instantaneous portion of movement from accelerometer data
#define kFilteringFactor 0.1
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration {
// Subtract the low-pass value from the current value to get a simplified high-pass filter
accelX = acceleration.x - ( (acceleration.x * kFilteringFactor) + (accelX * (1.0 - kFilteringFactor)) );
accelY = acceleration.y - ( (acceleration.y * kFilteringFactor) + (accelY * (1.0 - kFilteringFactor)) );
accelZ = acceleration.z - ( (acceleration.z * kFilteringFactor) + (accelZ * (1.0 - kFilteringFactor)) );
// Use the acceleration data.
}
I am using glLookAt to control my camera view.
I use the following code to rotate around.
SPEED_TURN is a Const of 0.16 (speed we turn at)
GLfloat v[] = {[self centerAtIndex:0] - [self eyeAtIndex:0],
[self centerAtIndex:1] - [self eyeAtIndex:1],
[self centerAtIndex:2] - [self eyeAtIndex:2]};
[self setCenter:[self eyeAtIndex:0] + cos(SPEED_TURN / 2)*v[0] - sin(SPEED_TURN / 2)*v[2] atIndex:0];
[self setCenter:[self eyeAtIndex:2] + sin(SPEED_TURN / 2)*v[0] + cos(SPEED_TURN / 2)*v[2] atIndex:2];
My question is, how to I get the angle of the camera in degrees?
I tried this
rotAngleDegs = (cos(-SPEED_TURN)*v[0] - sin(-SPEED_TURN)*v[2]) * 180 / PI
However that give numbers from -620 to +620
I don't think you are trying the right functions to give you the angle. The functions "cos()" and "sin()" both take your angle and map it to [-1,1]. If SPEED_TURN is the angle in radians, then you would just use:
float angleInDegrees = (SPEED_TURN * 180) / M_PI;
Take the degress you want and multiply them by pi divided på 180. Then you get the radians to enter:
Radians = Degrees * (pi / 180)
To get the degrees from radians:
Degrees = Radians * (180 / pi)
I'm trying to rotate a sprite using the accelerometer. when I tilt right, I want him to rotate slightly to the right, and when I tilt left, I want him to rotate slightly to the left...
Thanks in advance,
Reed
Firs off - in your h file you need to make the following variables:
UIAccelerationValue accelerationX;
UIAccelerationValue accelerationY;
float currentRawReading;
float calibrationOffset;
Also ensure that your h file has:
#interface myViewName : UIViewController <UIAccelerometerDelegate>
Then in your .m file just below your imports at the top put:
#define kFilteringFactor 0.05
CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};
CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;};
Then in your .m file on your viewDidLoad Function put:
UIAccelerometer *accel = [UIAccelerometer sharedAccelerometer];
accel.delegate = self;
accel.updateInterval = 1.0f/60.0f;
also add the following function to your .m file:
-(void) accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{
accelerationX = acceleration.x * kFilteringFactor + accelerationX * (1.0 - kFilteringFactor);
accelerationY = acceleration.y * kFilteringFactor + accelerationY * (1.0 - kFilteringFactor);
// keep the raw reading, to use during calibrations
currentRawReading = atan2(accelerationY, accelerationX);
float rotation = -RadiansToDegrees(currentRawReading);
targetView.transform = CGAffineTransformMakeRotation(-(DegreesToRadians(rotation)));
//targetView.transform = CGAffineTransformRotate(targetView.transform, -(rotation * 3)); //if you want easing
}
you will have to tweak it slightly based on what view or object you are targeting -- but thats pretty much it.
Hope this helps,
Michael
Shouldn't be too difficult. Just have somewhere in your code that handles the UIAccelerometerDelegate class and apply changes to your sprites based on the values you receive through parameters to the – accelerometer:didAccelerate: callback.
Apple docs for the delegate class are available at...
https://developer.apple.com/library/ios/#documentation/UIKit/Reference/UIAccelerometerDelegate_Protocol/UIAccelerometerDelegate/UIAccelerometerDelegate.html
In the delegate function of accelerometer just write the code -->>
float angleRadians = atanf((float)X_Position / (float)Y_Position);
float angleDegrees = CC_RADIANS_TO_DEGREES(angleRadians);
float cocosAngle = 1 * angleDegrees;
sprite.rotation = cocosAngle;
and the sprite will get rotated to desired angle with changes in the values of X_position, Y_Position and angle.
Njoy.. :)
I'm wanting to detect the orientation of the iPhone at 45 degree increments. Ideally I'd like to be able to get the angle of orientation along any axis.
The detection I need to do is similar to how Trism for the iPhone flashes an arrow towards the current bottom position of the screen when orientation changes.
I have something coded up but really don't understand how the accelerometer readings work and could use a nudge in the right direction. My current code logs the current angle but even when the phone is flat I get readings varying wildly a few times a second.
- (void) checkOrientation:(UIAccelerometer*)accelerometer didAccelerate:(UIAcceleration*)acceleration
{
int accelerationX = acceleration.x * kfilteringFactor + accelerationX * (1.0 - kfilteringFactor);
int accelerationY = acceleration.y * kfilteringFactor + accelerationY * (1.0 - kfilteringFactor);
float currentRawReading = (atan2(accelerationY, accelerationX)) * 180/M_PI;
NSLog(#"Angle: %f",currentRawReading);
}
Sample from log while phone is flat:
2009-06-16 17:29:07.987 [373:207] Angle: 0.162292
2009-06-16 17:29:07.994 [373:207] Angle: 179.838547
2009-06-16 17:29:08.014 [373:207] Angle: 179.836182
2009-06-16 17:29:08.032 [373:207] Angle: -90.000000
2009-06-16 17:29:08.046 [373:207] Angle: 179.890900
2009-06-16 17:29:08.059 [373:207] Angle: -90.000000
2009-06-16 17:29:08.074 [373:207] Angle: 179.917908
2009-06-16 17:29:08.088 [373:207] Angle: -179.950424
2009-06-16 17:29:08.106 [373:207] Angle: 90.000000
2009-06-16 17:29:08.119 [373:207] Angle: 90.000000
2009-06-16 17:29:08.134 [373:207] Angle: -179.720245
I think your problem is that you're using int variables when you want float.
I think the accelerationX and –Y should be instance variables and thus:
accelerationX = acceleration.x * kfilteringFactor + accelerationX * (1.0 - kfilteringFactor);
accelerationY = acceleration.y * kfilteringFactor + accelerationY * (1.0 - kfilteringFactor);
Should give you more what you were looking for.
The reason is that you're using local variables, while they shouldn't be local.
Try to do the following:
Declare instance variables:
#interface YourViewControllerClass: UIViewController {
float accelerationX, accelerationY;
}
...
other declarations
Update variables in accelerometer delegate:
accelerationX = acceleration.x * kfilteringFactor + accelerationX * (1.0 - kfilteringFactor);
accelerationY = acceleration.y * kfilteringFactor + accelerationY * (1.0 - kfilteringFactor);
It should give more precise results without sudden jumps.
i have implementing moving image using UIAccelerometer.I have used below code.
code:
float gravX = (acceleration. x * kFilteringFactor) + (gravX * (1 - kFilteringFactor));
float gravY = (acceleration. y * kFilteringFactor) + (gravY * (1 - kFilteringFactor));
float moveX = acceleration. x - gravX;
float moveY = acceleration. y - gravY;
CGPoint MoveCenter = [moveImage center];
float Movex = moveX * 30 + MoveCenter. x;
float Movey = moveY * 30 + MoveCenter. y;
moveImage.center = CGPointMake(Movex, Movey);
In this code there is one problem.If i move device on top side then image is moving on left side,if device is move left side then image is moving top side.can you give me advice.
Maybe is a problem of the coordinates. I'm not sure this is the problem but in Quartz the (0,0) is on bottom left while on UIKit is on top left.
Try to change the coordinates with frame.origin.x and frame.origin.y instead of using CGPoint.