Bones and Biped Matrix on translation

[Anonymous]

Hello,

I still working on a ogre export and I saw some strange effects on bone translations.
I get correct bone Orientation but with the same matrix I get a translation reverted on some axes depending of the parent bone.
Should I use a different matrix for translations ?

Here my code.

matrix manipulation code :

inline Matrix3 UniformMatrix(Matrix3 orig_cur_mat, bool yUp)
{
  AffineParts   parts;
  Matrix3       mat;

  Matrix3 YtoZ;
  Matrix3 ZtoY;

  GMatrix gmat;
  gmat.SetRow(0, Point4(1,  0, 0, 0));
  gmat.SetRow(1, Point4(0,  0, 1, 0));
  gmat.SetRow(2, Point4(0, -1, 0, 0));
  gmat.SetRow(3, Point4(0,  0, 0, 1));
  YtoZ = gmat.ExtractMatrix3();
  ZtoY = Inverse(YtoZ);

///Remove  scaling  from orig_cur_mat
//1) Decompose original and get decomposition info
  decomp_affine(orig_cur_mat, &parts); 

//2) construct 3x3 rotation from quaternion parts.q
  parts.q.MakeMatrix(mat);

//3) construct position row from translation parts.t  
  mat.SetRow(3,  parts.t);

  if (yUp)
    mat = YtoZ * mat * ZtoY;

 return(mat);
}

inline Matrix3 GetRelativeUniformMatrix(Matrix3 mat1, Matrix3 mat2, bool yUp)
{          
  Matrix3 dest_mat;
  
  //Decompose each matrix
  Matrix3 cur_mat = UniformMatrix(mat1, yUp);
  Matrix3 par_mat = UniformMatrix(mat2, yUp);
 
  //then return relative matrix in coordinate space of parent
  dest_mat = cur_mat * Inverse(par_mat);

  return dest_mat;
}

Now get the initial bone matrix

    // Get mesh matrix at initial pose
    ISkin* pskin = (ISkin*)m_pGameSkin->GetMaxModifier()->GetInterface(I_SKIN);

    GMatrix GSkinTM;
    m_pGameSkin->GetInitSkinTM(GSkinTM);
    Matrix3 SkinTM = GSkinTM.ExtractMatrix3();

    Matrix3 boneTM;
    Matrix3 ParentTM;

    if(pskin->GetBoneInitTM(pNode, boneTM, false) == SKIN_INVALID_NODE_PTR)
      boneTM = pNode->GetNodeTM(firstFrame);

    if(pskin->GetBoneInitTM(pNodeParent, ParentTM, false) == SKIN_INVALID_NODE_PTR)
      ParentTM = pNodeParent->GetNodeTM(firstFrame);

    Matrix3 localTM;
    if(parentIdx >= 0)
    {
      localTM = GetRelativeUniformMatrix(boneTM, ParentTM, m_params.yUpAxis);
    }
    else // for root bone use the mesh
    {
      localTM = GetRelativeUniformMatrix(boneTM, ParentTM, m_params.yUpAxis) * Inverse(SkinTM);
    }
    
    m_joints.bindMatrix = localTM;

And now getting the relative matrix by time

    INode* bone = j.pNode;
    
    // Get the bone local matrix for this key
    Matrix3 boneTM = GetRelativeUniformMatrix(bone, time, m_params.yUpAxis);

    GMatrix GSkinTM;
    m_pGameSkin->GetInitSkinTM(GSkinTM);
    Matrix3 SkinTM = GSkinTM.ExtractMatrix3();

    // for root bone use the mesh
    if(j.parentIndex < 0)
      boneTM = boneTM * Inverse(SkinTM);

    Matrix3 relMat = boneTM * Inverse(j.bindMatrix);

    AffineParts ap;
    decomp_affine(relMat, &ap);

    Point3 trans = ap.t * m_params.lum;
    Point3 scale = ap.k;
    Quat rot = ap.q;
    // Notice that in Max we flip the w-component of the quaternion;
    rot.w = -rot.w;

    //create keyframe
    skeletonKeyframe key;
    key.time = 0;

    // don't know why root translation are Z X reverted
    // what matrix should I use for translations ?
    if(IsBipedRoot(bone))
    {
      key.trans.x = -trans.z;
      key.trans.y = trans.y;
      key.trans.z = trans.x;
    }
    else if(IsBipedRoot(bone->GetParentNode()))
    {
      key.trans.x = trans.x;
      key.trans.y = -trans.z;
      key.trans.z = trans.y;
    }
    else
    {
      key.trans.x = trans.z;
      key.trans.y = trans.x;
      key.trans.z = trans.y;
    }

  key.rot = rot;
  key.scale = scale;
  return key;

So as you can see I use a strange hack to get the correct translation in some cases...

[Anonymous]

Up ^^ ?!

I still have the issue for the bones translations 😕
Any clue ?