Skew-T Diagrams
===============

.. _fig_skewt_actor:
.. figure:: ./figs/skewt/actorref_skewt.webp
    :figwidth: 100%
    :align: left
    :alt: A screenshot of the Skew-T actor in Met.3D.

    Skew-T log-p diagram actor in 3-D view on the left, a fullscreen view of
    the actor on the right in a separate view.


Description
-----------

The Skew-T actor renders a Skew-T log-p thermodynamic diagram displaying the
vertical profile of temperature and dew point temperature at a chosen
geographic location. The diagram can be rendered as a planar element inside
the 3-D scene, or it can fill an entire scene view in fullscreen mode for
detailed inspection.


Setup
-----

Add the Skew-T actor to the scene and then add two actor variables:

1. **Temperature**: select the temperature field from a 3-D dataset.
2. **Dew point temperature**: select the corresponding dew point field.

The colour of each profile line can be changed in the actor variable's
render settings. Once assigned, the diagram will show the vertical 
profile at the current position.


Positioning
-----------

The profile location is set via the **Position** property (longitude and
latitude). In actor interaction mode the profile pole (a vertical marker
anchored at the profile location) can be clicked and dragged to any position
in the scene. The Skew-T diagram updates live as the pole is dragged, making
it easy to interactively explore the temperature profiles across the domain.


Appearance
----------

The **Appearance** group controls the diagram layout:

* **Align with camera**: when enabled (default), the diagram plane always
  faces the camera. Disable to fix the plane orientation in world space.
* **3-D diagram width**: width of the diagram in the 3-D scene, in degrees
  of longitude.
* **Vertical extent**: pressure range displayed on the vertical axis
  (bottom and top in hPa).
* **Temperature minimum / maximum**: horizontal temperature range of the
  diagram in °C.
* **Isotherms spacing**: spacing between skewed isotherm lines (°C).
* **Skew factor**: controls how strongly the isotherms are tilted.
  A value of 0 gives a tephigram-style layout; 1 is the classical
  Skew-T skew; 2 skews isotherms more steeply. Default is 1.
* **Dry adiabates**: toggle and spacing for dry adiabat lines.
* **Moist adiabates**: toggle and spacing for moist (saturated) adiabat lines.


Fullscreen mode
---------------

The Skew-T actor supports a dedicated fullscreen mode where the diagram fills
an entire scene view. This is useful for detailed reading of the diagram
without the perspective distortion of the 3-D view.

To enable fullscreen mode for a scene view:

1. Open the **View specific settings** in the System tab (next to the scene 
   tabs), and select the view you want to use as fullscreen view.
2. Under **Camera and navigation**, look for **View and navigation mode**
   and select **Single full screen actor**.
3. An **Actor in fullscreen mode** selector will appear further down. Choose 
   the Skew-T actor from the list. Note that only actors are available that are
   rendered to this view.

The view will now render only the Skew-T diagram, filling the full viewport.
In interaction mode, hovering over the diagram draws interactive crosshair
lines: the isobar, isotherm, dry adiabat and moist adiabat passing through the
current mouse position are highlighted.

.. note::

   The fullscreen mode is per-view. Other scene views in the same session
   continue to show the full 3-D scene. A common setup is to use one view
   for the Skew-T diagram in fullscreen and one or more views for the 3-D
   scene.