   problem during a rotation of the 3D object
  // For the world matrix, rotate the object about the y-axis. // Set up the rotation matrix to generate one full rotation (2*PI radians)// every 1000 ms. To avoid the loss of precision inherent in very high// floating-point numbers, the system time is modulated by the rotation// period before conversion to a radian angle.int iTime = Environment.TickCount % 1000;float fAngle = iTime * (2.0f * (float)Math.PI) / 1000.0f;device.Transform.World = Matrix.RotationY(fAngle); I have to copy the code above since MSDN.I find of the evil has to understand  the role of the iTime variable in this instruction:float fAngle = iTime * (2.0f * (float)Math.PI) / 1000.0f;2) I do not see has what is going to serve us the variable Environment. TickCount in the code precedeIts  definition since MSDN:" Obtains the number of milliseconds sold since the starting up of the system ".3) If I would be worth making a single complete rotation which have to I makeI thank you for answering has these question[Edited by - eemii on April 21, 2010 3:07:22 PM]