Maths has never been a strong point of mine.

My problem is that I have a player model thats starts off in the game world and rotates left,right, up, down just fine when stationary. but as soon as the player moves away from the starting position the rotations go all wrong as if the martrixs arent being recalculated.

This is how I am currently calculating the matices in my update method. Any with better maths skills see where the error is?

public void Update(GameTime gameTime) { KeyboardState keyboardState = Keyboard.GetState(); float elapsed = (float)gameTime.ElapsedGameTime.TotalSeconds; if (keyboardState.IsKeyDown(Keys.Left)) { shipColBox.AngularVelocity = Vector3.Up; } if (keyboardState.IsKeyDown(Keys.Right)) { shipColBox.AngularVelocity = Vector3.Down; } if (keyboardState.IsKeyDown(Keys.Up)) { shipColBox.AngularVelocity = Vector3.Left; } if (keyboardState.IsKeyDown(Keys.Down)) { shipColBox.AngularVelocity = Vector3.Right; } // Scale rotation amount to radians per second shipColBox.AngularVelocity = shipColBox.AngularVelocity * RotationRate * elapsed; //Create rotation matrix Matrix rotationMatrix = Matrix.CreateFromAxisAngle(Right, shipColBox.AngularVelocity.Y) * Matrix.CreateRotationY(shipColBox.AngularVelocity.X); //Rotate orientation vectors Direction = Vector3.TransformNormal(Direction, rotationMatrix); Up = Vector3.TransformNormal(Up, rotationMatrix); // Re-normalize orientation vectors Direction.Normalize(); Up.Normalize(); // Re-calculate Right right = Vector3.Cross(Direction, Up); // re-calculate with a cross product to ensure orthagonality Up = Vector3.Cross(Right, Direction); // Determine thrust amount from input if (keyboardState.IsKeyDown(Keys.W)) { thrustAmount = 5.0f; } else { thrustAmount = 0; shipColBox.LinearVelocity = new Vector3(0, 0, 0f); } // Calculate force from thrust amount Vector3 force = shipColBox.OrientationMatrix.Forward * thrustAmount * ThrustForce; // Apply acceleration Vector3 acceleration = force / shipColBox.Mass; Velocity += acceleration * elapsed; //Apply psuedo drag Velocity *= DragFactor; //Apply velocity shipColBox.Position += Velocity * elapsed; // Reconstruct the ship's world matrix world = Matrix.Identity; world.Forward = Direction; world.Up = Up; world.Right = right; world.Translation = Position; }