Extracting rotation from matrix

The forum is locked. These are the original blitzbasic.com forums, kept so they can still be read. No new topics, replies or edits can be made here. To join in, head over to the Blitz3D+ forums.

Tom

From Sweenies Tokamak Wrapper:

neV3 Mat3ToEulerZXY(neM3 Matrix)
{
	float m_afEntry[9];
	float rfXAngle;
	float rfYAngle;
	float rfZAngle;

	neV3 Result;
	
	m_afEntry[0] = Matrix.M[0].v[0];
	m_afEntry[1] = Matrix.M[0].v[1];
	m_afEntry[2] = Matrix.M[0].v[2];
	m_afEntry[3] = Matrix.M[1].v[0];
	m_afEntry[4] = Matrix.M[1].v[1];
	m_afEntry[5] = Matrix.M[1].v[2];
	m_afEntry[6] = Matrix.M[2].v[0];
	m_afEntry[7] = Matrix.M[2].v[1];
	m_afEntry[8] = Matrix.M[2].v[2];


    if ( m_afEntry[7] < 1.0f )
    {
        if ( m_afEntry[7] > -1.0f )
        {
           rfZAngle = (float)atan2(-m_afEntry[1],m_afEntry[4]);
           rfXAngle = (float)asin((double)m_afEntry[7]);
           rfYAngle = (float)atan2(-m_afEntry[6],m_afEntry[8]);
			Result.v[0] = rfXAngle;
			Result.v[1] = rfYAngle;
			Result.v[2] = rfZAngle;
            return Result;
        }
        else
        {
            // WARNING.  Not unique.  ZA - YA = -atan(r02,r00)
            rfZAngle = (float)-atan2(m_afEntry[2],m_afEntry[0]);
            rfXAngle = -1.570796f;
            rfYAngle = 0.0f;
			Result.v[0] = rfXAngle;
			Result.v[1] = rfYAngle;
			Result.v[2] = rfZAngle;
            return Result;
        }
    }
    else
    {
        // WARNING.  Not unique.  ZA + YA = atan2(r02,r00)
		rfZAngle = (float)atan2(m_afEntry[2],m_afEntry[0]);
		rfXAngle = 1.570796f;
		rfYAngle = 0.0f;
		Result.v[0] = rfXAngle;
		Result.v[1] = rfYAngle;
		Result.v[2] = rfZAngle;
        return Result;
    }
}

Check out Marks native code too:
http://www.blitzbasic.com/Community/posts.php?topic=42657