Useful little code: Vector orientation

Started by pachesantiago, Oct 15 2012 11:31 AM

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#1 pachesantiago Members - Reputation: 119

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Posted 15 October 2012 - 11:31 AM

Hy everyone. I'm posting this little code i put toghether today ( taken from DXUT and modifed acctually), wich i had been serching for a long time.
It allows to orientate an object using a target vector and a postion vector.
Here it is :


D3DXVECTOR2 GetYawPitchFromVectors(D3DXVECTOR3* pvEyePt, D3DXVECTOR3* pvLookatPt)
{
	 D3DXMATRIX m_mView;
	// Calc the view matrix
	D3DXVECTOR3 vUp( 0,1,0 );
	D3DXMatrixLookAtLH( &m_mView, pvEyePt, pvLookatPt, &vUp );
	D3DXMATRIX mInvView;
	D3DXMatrixInverse( &mInvView, NULL, &m_mView );
	// The axis basis vectors and camera position are stored inside the
	// position matrix in the 4 rows of the camera's world matrix.
	// To figure out the yaw/pitch of the camera, we just need the Z basis vector
	D3DXVECTOR3* pZBasis = ( D3DXVECTOR3* )&mInvView._31;
	D3DXVECTOR2 data;
	data.x = atan2f( pZBasis->x, pZBasis->z );
	float fLen = sqrtf( pZBasis->z * pZBasis->z + pZBasis->x * pZBasis->x );
	data.y = -atan2f( pZBasis->y, fLen );
	 return data;
}

Edited by pachesantiago, 15 October 2012 - 11:39 AM.

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