Rotation problem

[Peter Müller]

Hi!
I've got a problem concerning the rotation of an vector (core::vector3d).



On the delineation you can see an 3D unit circle, described the the normalized direction vector.

If I rotate the vector

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vector3df vDirection(0,0,1);

horizontal using the rotateXZBy method

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this->vDirection->rotateXZBy(10.0f, vector3df(0,0,0));

everythink is perfect and the vector is rotating like the red circle.

But if I want to rotate vertical, from point 1 to point 2 using the rotateXYBy method

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this->vDirection->rotateXYBy(10.0f, vector3df(0,0,0));

it doesn't rotate like the purple line is showing. Its rotating like the yellow circle

I also tried to use the rotateYZBy method and both, the rotateXYBy and rotateYZBy methods. Nothing helped.

While the horizontal rotation works perfect, the vertical went nuts.

Can somebody help me?

[T101]

I think you're suffering from gimbal lock.

What you probably want to do is go from a yaw/pitch(/roll) rotation to a vector. (With roll being local to the camera)

Assuming you start with your vector pointing along the X-axis:

1. rotate first by roll (with just a vector roll is not applicable, like with a camera in an editor, but with offsets it is) - with Irrlicht this would be in the Y/Z plane I believe.
2. rotate by pitch - with Irrlicht this is the X/Y plane
3. rotate by yaw - in the X/Z plane

[Peter Müller]

Thanks, i'll try it