Le 09/02/2013 15:39, Roman Haefeli a écrit :
I believe it is (unfortunately) not as simple as that. When you rotate
with [rotateXYZ], the three axis are not always perpendicular to each
other. For instance, if you set Y to 90, the X and the Z rotate around
the same axis.
every rotation keep the 3 axes perpendicular.
but rotateXYZ do 3 rotations, X, Y and Z, in this order.
if you rotate 90° in Y, Z axe became what use to be the X axe.
so rotation in Z after a 90° rotation in Y is the same than a rotation in X
before the Y rotation.
that's the gimbal lock.
but after the Y rotation, a X rotation is not the same than a Z rotation.
if you don't believe me, you can try :
gemhead
rotate X 0 Z
rotate 0 90 0
cube
X and Z are still (and will always be) perpendicular.
However, the gyroscope (at least the one from Wiimote MotionPlus and
most likely also the one from your phone) consists of three separate
sensor which are perpendicular to each other at any time.
If I understand Fero correctly, he would like to use the sensors so he
can control an object in Gem that follows exactly the orientation of his
phone. I also tried that once with a Wiimote and Gem but I couldn't wrap
my head around the two concepts of [rotateXYZ] and the gyro sensors.
gyro sensors give rotation speed. not absolute rotation.
in theory (with infinite acurate sensors, no drift etc), you have to do a
feedback loop (using gemlist_info), so that the current rotation is modify by
the sensors value.
(rotation did not sums up)
cheers
c
Anyone enlightened might be able to shed some light on this confusion?
Roman
On Sam, 2013-02-09 at 15:18 +0100, Cyrille Henry wrote:
hello,
rotateXYZ is doing : rotation X then rotation Y then rotation Z
this is not the same than :
rotation Z
rotation Y
rotation X
So, depending on how works your orientation sensors, you could have to change
the rotation order.
you can try, using 3 rotateXYZ object.
cheers
c
Le 09/02/2013 14:45, Fero Kiraly a écrit :
I have 3 axis accelerometer and 3 axis orientation sensor in my device.
So i can get 0 - 360 deg on X, Y and Z.
When I draw in GEM a rectangle, I am able to rotate it with each of 3 axes, but
only separately. When I try it with all three axes together
it has strange movements, so I guess it has something with gimbal lock.
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