How do I calculate the Rotation in Radians around Z-axis by giving a CATransform3D struct as the input?
basically what I need is the other way round of CATransform3DMakeRotation.
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74answers:
1Be sure to use atan2 and not atan as the later will not give an angle in the correct quadrant.
Nader
2010-10-15 13:02:05
Thank you Nader, before your answer, I had resorted back to using CALayer's affineTransform property convert the Transform3D into an AffineTransform and then get the angle out of it from this calculation:http://stackoverflow.com/questions/2051811/iphone-sdk-cgaffinetransform-getting-the-angle-of-rotation-of-an-objectNow I know, how to calculate directly from Transform3D. Thanks!
ravinsp
2010-10-16 06:18:44
Yeah I learned about this back in first year uni and can remember asking my friend "why the he'll do we need to know this"
Nader
2010-10-16 12:51:45
You can calculate the angle from an affine transform too using atan2(transform.b, transform.a), the maths still holds true for a z-axis rotation
Nader
2010-10-16 13:00:21