public void Rotate()
{
float yawRad = MathUtilities.DegreesToRadians(Yaw);
float pitchRad = MathUtilities.DegreesToRadians(Pitch);
float rollRad = MathUtilities.DegreesToRadians(Roll);
// There are two contexts of "handedness" at play in any camera's
// coordinate system. One is the concern of which way the positive
// ends of the axes point, with "left-handed" coordinates having the
// positive Z axis point in the direction the camera is looking, and
// "right-handed" being the opposite. The other handedness concerns
// the direction of rotations, with the "left hand rule" being that
// rotations about a given axis go clockwise when looking toward the
// negative direction of that axis, while the "right hand rule" has
// the rotations go counter-clockwise.
//
// This camera uses right-handed coordinate space, but aims to also
// use right hand rotation, which complicates these calculations a
// little bit.
//
// When looking "down" at a given plane, that is to say looking in
// the negative direction of the perpendicular axis, one axis runs
// horizontally relative to the view and one runs vertically.
//
// Rotating a unit vector within that plane requires modifying two
// of its components, one per axis. For the vertical axis, taking
// the sine of the rotation value for the axis of rotation will in
// fact give you a counter-clockwise turn, but only assuming the
// positive ends of the horizontal and vertical axes point right and
// up, respectively.
//
// This plugin's coordinate system being right-handed, pitch is not
// an issue, and simply taking the sine of the pitch value gives the
// new Y component of the front vector. Yaw is a different story,
// thanks to the direction of the positive Z axis, and negating the
// sine result becomes necessary to achieve the right hand rule and
// produce counter-clockwise rotation.
Front.X = Convert.ToSingle(Math.Cos(pitchRad) * Math.Cos(yawRad));
Front.Y = Convert.ToSingle(Math.Sin(pitchRad));
Front.Z = Convert.ToSingle(Math.Cos(pitchRad) * -Math.Sin(yawRad));
Front = Vector3.Normalize(Front);
Right = Vector3.Normalize(Vector3.Cross(Front, WorldUp));
Matrix4x4 matrixRoll = Matrix4x4.CreateFromAxisAngle(Front, rollRad);
Right = Vector3.Transform(Right, matrixRoll);
Up = Vector3.Normalize(Vector3.Cross(Right, Front));
ViewMatrix = Matrix4x4.CreateLookAt(Position, Position + Front, Up);
Frustum.Update(Position, Front, Right, Up, Fov, AspectRatio, NearClip, FarClip);
}
public void UpdateProjectionMatrix()
{
ProjectionMatrix = Matrix4x4.CreatePerspectiveFieldOfView(MathUtilities.DegreesToRadians(Fov), AspectRatio, NearClip, FarClip);
Frustum.Update(Position, Front, Right, Up, Fov, AspectRatio, NearClip, FarClip);
}
