Object Rotations...

[LucaEstiva]

//------------------------------------------------------------------------------------------------------------
/**

• Rotate the object passed as param by the angle specified. The rotation happen only about the specified axis

• @param SourceObject:Object - The object that must by rotated

• @param X:Number( Degrees ) - The angle, of rotation

• @param Y:Number( Degrees ) - The angle, of rotation

• @param RotationAxis:Vector3D - The vector tha specify the axis of rotation
  */
  //------------------------------------------------------------------------------------------------------------
  public function RotateObjectByArbitraryAxis( SourceObject:Object, X:Number, Y:Number, RotationAxis:Vector3D ):void
  {

  // GET THE ORIGINAL OBJECT TRANSFORM MATRIX
  var m:Matrix3D = SourceObject.transform;
  // ROTATION EULER BY QUATERNION
  var rv:Vector3D = new Vector3D();

  // The first Vector3D object holds the translation elements.
  // The second Vector3D object holds the rotation elements.
  // The third Vector3D object holds the scale elements.
  var VM:Vector. = m.decompose();
  // ROTATION QUATERNION
  var QRotation:Quaternion = new Quaternion();

  // NEW TRANSFORM MATRIX
  var mm:Matrix3D = new Matrix3D();

  // A Vector of 16 Numbers, where every four elements is a column of a 4x4 matrix.
  var RawMatrixData:Vector. = m.rawData;

  // ONLY ROTATION DATA REMAIN UNCHANGED
  RawMatrixData[3] = 0;
  RawMatrixData[7] = 0;
  RawMatrixData[11] = 0;
  RawMatrixData[12] = 0;
  RawMatrixData[13] = 0;
  RawMatrixData[14] = 0;
  RawMatrixData[15] = 1;
  // COPY ROTATION DATA IN TO THE NEW TRANSFORM MATRIX
  mm.copyRawDataFrom( RawMatrixData );

  // MAKE A NEW QUATERNION FROM THE NEW TRANSFORM MATRIX
  QRotation.fromMatrix( mm );
  // NORMALIZE QUATERNION
  QRotation.normalize();

  // ADD ROTATION BY ARBITRARY AXIS
  if( RotationAxis.x ) // ROLL
  {
  // Add rotation about X axis
  QRotation.fromAxisAngle( Vector3D.X_AXIS, X * DEGREES_TO_RADIANS );
  }
  else if( RotationAxis.y ) // YAW
  {
  // Add rotation about Y axis
  QRotation.fromAxisAngle( Vector3D.Y_AXIS, Y * DEGREES_TO_RADIANS );
  }
  else if( RotationAxis.z ) // PITCH
  {
  // Add rotation about Z axis
  QRotation.fromAxisAngle( Vector3D.Z_AXIS, X * DEGREES_TO_RADIANS );
  }

  //
  QRotation.normalize();
  // GET ANGLE OF ROTATIONS FROM QUATERNION
  QRotation.toEulerAngles( rv );

  // UPDATE THE NEW TRANSFORM MATRIX
  mm.appendRotation( rv.x * RADIANS_TO_DEGREES, Vector3D.X_AXIS );
  mm.appendRotation( rv.y * RADIANS_TO_DEGREES, Vector3D.Y_AXIS );
  mm.appendRotation( rv.z * RADIANS_TO_DEGREES, Vector3D.Z_AXIS );
  mm.appendTranslation( VM[0].x, VM[0].y, VM[0].z );
  mm.appendScale( VM[2].x, VM[2].y, VM[2].z );
  // COPY THE NEW MATRIX IN TO THE ORIGINAL MATRIX
  m.copyFrom( mm );
  // APPLY THE NEW TRANSFORM TO THE OBJECT
  SourceObject.transform = m;
  }