public void UpdateCamera(GameTime gameTime)
{
if (_animation != null)
{
_animation.Update(this, gameTime);
if (_animation.Finished)
{
_animation = null;
}
}
var yaw = MathUtility.Atan2(_lookDirection.Y, _lookDirection.X);
var pitch = MathUtility.Lerp(
0,
-_pitchAngle,
_pitch);
var cameraHeight = MathUtility.Lerp(
0,
_defaultHeight,
_zoom);
float clampedPitch = pitch;
if (pitch > 0 && pitch < _pitchAngle)
{
clampedPitch = _pitchAngle;
}
else if (pitch < 0 && pitch > -_pitchAngle)
{
clampedPitch = -_pitchAngle;
}
var cameraToTerrainDirection = Vector3.Normalize(new Vector3(
MathUtility.Cos(yaw),
MathUtility.Sin(yaw),
MathUtility.Sin(clampedPitch)));
// Back up camera from terrain position.
var toCameraRay = new Ray(_terrainPosition, -cameraToTerrainDirection);
var plane = Plane.CreateFromVertices(
new Vector3(0, 0, cameraHeight),
new Vector3(0, 1, cameraHeight),
new Vector3(1, 0, cameraHeight));
var toCameraIntersectionDistance = toCameraRay.Intersects(ref plane).Value;
var newPosition = _terrainPosition - cameraToTerrainDirection * toCameraIntersectionDistance;
// Pitch - 0 means top-down view.
// Pitch between 0 and CameraPitch = Move camera position to match pitch.
// Pitch between CameraPitch and horizontal = Raise or lower target height.
var lookDirection = new Vector3(
MathUtility.Cos(yaw),
MathUtility.Sin(yaw),
MathUtility.Sin(pitch));
var targetPosition = newPosition + lookDirection;
_camera.View = Matrix4x4.CreateLookAt(
newPosition,
targetPosition,
Vector3.UnitZ);
}
