[away3d] Re: Quaternion based FreeCam

[vangojames]

Thanks for the quick response Michael. Here is my update method:

/**
 * Handles renders
 */
private function update(dt:Number):void
{
        // recalculate the movement (this just takes inputs and populates)
        // the _tempRot Vector with dt * _angularSpeed
        updateMovementRotation(dt);

        // reset quaternions
        clearQuat(_tempRotQuat);
        clearQuat(_tempYawQuat);
        clearQuat(_tempPitchQuat);
        clearQuat(_tempRollQuat);

        // recalculate temp quaternions
        _tempPitchQuat.fromAxisAngle(Vector3D.X_AXIS, _tempRot.x);
        _tempYawQuat.fromAxisAngle(Vector3D.Y_AXIS, _tempRot.y);
        _tempRollQuat.fromAxisAngle(Vector3D.Z_AXIS, _tempRot.z);

        // apply quaternion rotations
        _tempRotQuat.multiply(_tempRotQuat, _tempPitchQuat);
        _tempRotQuat.multiply(_tempRotQuat, _tempYawQuat);
        _tempRotQuat.multiply(_tempRotQuat, _tempRollQuat);

        // apply to current rotation
        _camRot.multiply(_camRot, _tempRotQuat);

        // clear cam mat and update with the new rotation
        _target = _camRot.rotatePoint(Vector3D.Z_AXIS);
        _up =_camRot.rotatePoint(Vector3D.Y_AXIS);

        // apply look at to new target and up
        lookAt(_target, _up);
}

I'm sure I'm doing lots wrong, I haven't looked at Quaternions since
University and I can't remember how they work!! I just know they will
get rid of the dreaded Gimbal Lock,

Thanks,

James

On Apr 30, 12:00 pm, Michael Iv <explomas...@gmail.com> wrote:
> If you can post the full code of your quaternion operation may be I can help 
> then .
>
> Sent from my iPhone
>
> On Apr 30, 2011, at 1:52 PM, vangojames <vangoja...@gmail.com> wrote:
>
>
>
>
>
>
>
> > Hi guys,
>
> > Please help me. I'm really stuck at trying to implement a Quaternion
> > based free camera. My current approach is this:
>
> > ON EACH UPDATE::
>
> > - Get yaw pitch and roll increase
> > - Create quaternions for yaw, pitch and roll (for example
> > Quaternion.fromAxisAngle(Vector3D.X_AXIS, pitch))
> > - Multiply together in order pitch * yaw * roll to get new temp
> > quaternion
> > - Multiply cameraRotation quaternion by this new temp quaternion
> > - Calculate target by doing
> > cameraRotation.rotatePoint(Vector3D.Z_AXIS);
> > - Calculate up by doing cameraRotation.rotatePoint(Vector3D.Y_AXIS);
> > - lookAt(trget, up)
>
> > Needless to say this doesn't work. I just get the tiniest amount of
> > movement and it isn't what is expected at all. Would someone be able
> > to explain the correct approach?
>
> > Thanks!!
>
> > James