Horde3D

// Get absolute transformation of node, since OpenAL uses absolute transformations by default unless you specified
// that transformations are defined relative to the listener
const float* absMatPtr  = Horde3D::getNodeTransformMatrices(node, 0, &mat);
Matrix4f absMat(absMatPtr);
// Remove translation
absMat.x[12] = 0; absMat.x[13] = 0; absMat.x[14] = 0;
Vec3f forward = (absMat * Vec3f( 0 0 -1 ) ).normalize() ;
Vec3f up = (absMat * Vec3f( 0 1 0 ) ).normalize() ;
 

   
   // Precalculate cos and sin values for better performance
   const float cosx = cosf(x);
   const float sinx = sinf(x);
   const float cosy = cosf(y);
   const float siny = sinf(y);
   const float cosz = cosf(z);
   const float sinz = sinf(z);

   // Transform 0 0 -1 (At-Vector) with current rotation
   m_listenerOri[0] = - siny*cosx;
   m_listenerOri[1] = (sinx);
   m_listenerOri[2] = - (cosx * cosy);
   // Transform 0 1 0 (Up-Vector) with current rotation
   m_listenerOri[3] = - (cosy*sinz+siny*sinx*cosz);
   m_listenerOri[4] = (cosx*cosz);
   m_listenerOri[5] = (siny*sinz+cosy*sinx*cosz);

const float* absMatPtr  = Horde3D::getNodeTransformMatrices(node, 0, &mat); this was not working
 h3dGetNodeTransMats(p->m_characterID,0,&relMat);   I used this because i think its almost the same function
      Matrix4f absMat(relMat);
     absMat.x[12] = 0; absMat.x[13] = 0; absMat.x[14] = 0;
      //Vec3f forward = (absMat * Vec3f(0,0,-1 ) ).normalize(); This was not working
     Vec3f forward = absMat * Vec3f(0,0,-1 );
     forward.normalize();

   float getAngle(H3DNode from, H3DNode to)
   {
       Matrix4f relMat = Matrix4f();
       h3dGetNodeTransMats(from,0,&relMat);
       Matrix4f fromAbsMat(relMat);
       h3dGetNodeTransMats(to,0,&relMat);
       Matrix4f toAbsMat(relMat);
      
       // [x1, y1, z1, w1]    0, 1, 2, 3
       // [x2, y2, z2, w2]    4, 5, 6, 7
       // [x3, y3, z3, w3]    8, 9, 10, 11
       // [x4, y4, z4, w4]    12, 13, 14, 15
      
       // x4 aka. 12, y4 aka. 13, z4 aka. 14 are translation values
       // v1 is your vector between 'from' and 'to'
       Vec3f v1 = Vec3f(toAbsMat.x[12] - fromAbsMat.x[12], toAbsMat.x[13] - fromAbsMat.x[13], toAbsMat.x[14] - fromAbsMat.x[14]);
       v1.normalize(); // you need to normalize it so length will be == 1
       absMat.x[12] = 0; absMat.x[13] = 0; absMat.x[14] = 0;   // i don't really know why .x is there, but i'm usually not programming in C++
       Vec3f v2 = from * Vec3f(0,0,-1); // flip Z axis ??
       v2.normalize(); // it needs to be normalized as well
       return acos(v2.dot(v1));
   }