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papa

Get rotation angles from D3DXMATRIX

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Hi. I have an orientation quaternion from which I extracted the rotation matrix and now I need to get rotation in XYZ euler angles. Is there any way to do it using dx9 math lib? or any other simple way? The code I wrote is:
void GetRotation( D3DXVECTOR3 *angles_out, D3DXQUATERNION *qrot )
{ 
D3DXQuaternionNormalize(qrot, qrot); 
D3DXMATRIX rot;
D3DXMatrixIdentity(&rot);
// Get rotation matrix from this quat
D3DXMatrixRotationQuaternion( &rot, qrot);

// Here finally I need to extract euler angles from "rot" matrix and put it 
// into 3D vector(xyz) "angles_out". 
}

Any ideas how to do this?

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Check the docs at Magic Software. Dave does discuss extracting Euler angles from a rotation matrix. Not DX specific, but doesn't need to be. The only consideration might be the row-wise vs. column-wise orientation, e.g., you might have to take the transpose of the rotation part before applying Dave's formulas.

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it is possible to transform a point by a matrix
like this but I am not sure what I should do then.

D3DXVECTOR3 X = D3DXVECTOR3(1,0,0);
D3DXVECTOR3 Y = D3DXVECTOR3(0,1,0);
D3DXVECTOR3 Z = D3DXVECTOR3(0,0,1);

D3DXVec3TransformCoord(&X, &X, &rot); // trnasform 3D point by rotation matrix
D3DXVec3TransformCoord(&Y, &Y, &rot); // trnasform 3D point by rotation matrix
D3DXVec3TransformCoord(&Z, &Z, &rot); // trnasform 3D point by rotation matrix

at this statge I think I rotated each axis by "rot" matrix. but still I dont know how to combine those three 3D vectors into 1 3D vector (xyz) with correct euler angles.

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