Magic Cube

  private void modifyCurrentPosition(Static4D quat)

    float cubitCenterX = mCurrentPosition.get0();

    float cubitCenterY = mCurrentPosition.get1();

    float cubitCenterZ = mCurrentPosition.get2();

    mCurrentPosition.set(rotatedX, rotatedY, rotatedZ);

    mParent.clampPos(mCurrentPosition);

    modifyCurrentPosition(mQuatScramble);

    }

///////////////////////////////////////////////////////////////////////////////////////////////////

// return if the Cubit, when rotated with its own mQuatScramble, would have looked any different

// then if it were rotated by quaternion 'quat'.

// No it is not so simple as the quats need to be the same - imagine a 4x4x4 cube where the two

// middle squares get interchanged. No visible difference!

//

// So: this is true iff the cubit

// a) is a corner or edge and the quaternions are the same

// b) is inside one of the faces and after rotations by both quats it ends up on the same face.

  boolean thereIsNoVisibleDifference(Static4D quat)

    {

    if ( mQuatScramble.get0()==quat.get0() &&

         mQuatScramble.get1()==quat.get1() &&

         mQuatScramble.get2()==quat.get2() &&

         mQuatScramble.get3()==quat.get3()  ) return true;

    int belongsToHowManyFaces = 0;

    int size = mParent.getSize()-1;

    int row;

    for(int i=0; i<mNumAxis; i++)

      {

      row = (int)(mRotationRow[i]+0.5f);

      if( row==0 || row==size ) belongsToHowManyFaces++;

      }

    switch(belongsToHowManyFaces)

      {

      case 0 : return true ;  // 'inside' cubit that does not lie on any face

      case 1 :                // cubit that lies inside one of the faces

               float cubitCenterX = mCurrentPosition.get0();

               float cubitCenterY = mCurrentPosition.get1();

               float cubitCenterZ = mCurrentPosition.get2();

               Static4D cubitCenter = new Static4D(cubitCenterX, cubitCenterY, cubitCenterZ, 0);

               Static4D rotated1 = RubikSurfaceView.rotateVectorByQuat( cubitCenter, quat);

               Static4D rotated2 = RubikSurfaceView.rotateVectorByQuat( cubitCenter, mQuatScramble );

               int row1, row2;

               float ax,ay,az;

               Static3D axis;

               float x1 = rotated1.get0();

               float y1 = rotated1.get1();

               float z1 = rotated1.get2();

               float x2 = rotated2.get0();

               float y2 = rotated2.get1();

               float z2 = rotated2.get2();

               for(int i=0; i<mNumAxis; i++)

                 {

                 axis = mParent.ROTATION_AXIS[i];

                 ax = axis.get0();

                 ay = axis.get1();

                 az = axis.get2();

                 row1 = (int)(( (x1*ax + y1*ay + z1*az) - mParent.mStart)/mParent.mStep + 0.5f);

                 row2 = (int)(( (x2*ax + y2*ay + z2*az) - mParent.mStart)/mParent.mStep + 0.5f);

                 if( (row1==0 && row2==0) || (row1==size && row2==size) )

                   {

                   return true;

                   }

                 }

               return false;

      default: return false;  // edge or corner

      }

    modifyCurrentPosition(quat);