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Rotation of a vector by a matrix and a quaternion are not equivalent #97

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mxrie-eve opened this issue Nov 22, 2019 · 1 comment · May be fixed by #98
Open

Rotation of a vector by a matrix and a quaternion are not equivalent #97

mxrie-eve opened this issue Nov 22, 2019 · 1 comment · May be fixed by #98

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@mxrie-eve
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To reproduce the bug:

m = matrix44.create_from_x_rotation(np.pi / 2.)
matrix44.apply_to_vector(m, [0., 1., 0., 1.])
# gives:
array([ 0.000000e+00, 0.000000e+00, -1.000000e+00,  1.000000e+00])

And

q = quaternion.create_from_x_rotation(np.pi / 2.)
quaternion.apply_to_vector(q, [0., 1., 0., 1.])
# gives:
array([0.00000000e+00, 0.00000000e+00, 1.00000000e+00, 1.00000000e+00])

When you test the equivalence of the relation in test_m44_q_equivalence, you rotate a unit vector on the x-axis by the x-axis. The vector won't move as it is aligned with the axis of rotation...
The bug is visible when you check with unit vectors on the y-axis or z-axis, like above.
@adamlwgriffiths
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Hey, thanks for looking into it and providing some examples.
Unfortunately I just don't have time to look at these issues.
If yourself or anyone else can address it, I'd be most greatful.

@mxrie-eve mxrie-eve linked a pull request Nov 28, 2019 that will close this issue
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@adamlwgriffiths adamlwgriffiths mentioned this issue Jun 8, 2023
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Bug/fix matrix apply to vector mxrie-eve/Pyrr
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@adamlwgriffiths @mxrie-eve