# -*- coding: utf-8 -*-
u"""
Package xrt is a python software library for ray tracing and wave propagation
in x-ray regime. It is primarily meant for modeling synchrotron sources,
beamlines and beamline elements. Includes a GUI for creating a beamline and
interactively viewing it in 3D.

+----------------+---------------+-----------+
|     |Itot|     |   |vcmSi-P|   | |VortexB| |
+----------------+---------------+-----------+

.. |Itot| animation:: _images/Itot
   :alt: &ensp;Intensity of undulator radiation on a transverse flat screen.
       The long axis is energy. One can observe two harmonics crossing the
       central line: the one at 2400 eV is odd and the one at 4800 eV is even.

.. |vcmSi-P| animation:: _images/vcmSi-FootprintP
   :alt: &ensp;Absorbed power and power density on a mirror at varying pitch
       angle.
   :loc: upper-right-corner

.. |VortexB| animation:: _images/Laguerre-Gauss-ani
   :alt: &ensp;Vortex beam with <i>l</i>=1 and <i>p</i>=1. Colored by phase.
   :loc: upper-right-corner

.. _guis:

GUIs
----

.. tabs::

   .. tab:: xrtQook
       .. automodule:: xrt.gui.xrtQook

   .. tab:: xrtGlow
       .. automodule:: xrt.gui.xrtGlow

   .. tab:: xrtBentXtal
       .. automodule:: xrt.gui.xrtBentXtal

Features of xrt
---------------

* *Rays and waves*. Classical ray tracing and :ref:`wave propagation <waves>`
  via Kirchhoff integrals, also freely intermixed. No further approximations,
  such as thin lens or paraxial. The optical surfaces may have :ref:`figure
  errors, analytical or measured<warping>`. In wave propagation, partially
  coherent radiation is treated by incoherent addition of coherently diffracted
  fields generated per electron. Propagation of :ref:`individual coherent
  source modes<modes>` is possible as waves, hybrid waves (i.e. partially as
  rays and then as waves) and only rays.

* *Publication quality graphics*. 1D and 2D position histograms are
  *simultaneously* coded by hue and brightness. Typically, colors represent
  energy and brightness represents beam intensity. The user may select other
  quantities to be encoded by colors: angular and positional distributions,
  various polarization properties, beam categories, number of reflections,
  incidence angle etc. Brightness can also encode partial flux for a selected
  polarization and incident or absorbed power. Publication quality plots are
  provided by `matplotlib <http://matplotlib.org>`_ with image formats PNG,
  PostScript, PDF and SVG.

* *Unlimited number of rays*. The colored histograms are *cumulative*. The
  accumulation can be stopped and resumed.

* *Parallel execution*. xrt can be run :ref:`in parallel <tests>` in several
  threads or processes (can be opted), which accelerates the execution on
  multi-core computers. Alternatively, xrt can use the power of GPUs via OpenCL
  for running special tasks such as the calculation of an undulator source or
  performing wave propagation.

* *Scripting in Python*. xrt can be run within Python scripts to generate a
  series of images under changing geometrical or physical parameters. The image
  brightness and 1D histograms can be normalized to the global maximum
  throughout the series.

* :ref:`Synchrotron sources <synchrotron-sources>`. Bending magnet, wiggler,
  undulator and elliptic undulator are calculated internally within xrt.
  Please look the section :ref:`comparison-synchrotron-sources` for the
  comparison with other popular codes. If the photon source is one of the
  synchrotron sources, the total flux in the beam is reported not just in
  number of rays but in physical units of ph/s. The total power or absorbed
  power can be opted instead of flux and is reported in W. The power density
  can be visualized by isolines. The magnetic gap of undulators can be
  :ref:`tapered <tapering_comparison>`. Undulators can be calculated in
  :ref:`near field <near_field_comparison>`. :ref:`Custom magnetic field
  <undulator_custom>` is also possible. Undulators can be :ref:`calculated on
  GPU <calculations_on_GPU>`, with a high gain in computation speed, which is
  important for tapering and near field calculations.

* *Shapes*. There are several predefined shapes of optical elements implemented
  as python classes. The python inheritance mechanism simplifies creation of
  other shapes: the user specifies methods for surface height and surface
  normal. The surface and the normal are defined either in local Cartesian
  coordinates or in user-defined parametric coordinates. Parametric
  representation enables closed shapes such as capillaries or wave guides. It
  also enables exact solutions for complex shapes (e.g. a logarithmic spiral or
  an ellipsoid) without any expansion. The methods of finding the intersections
  of rays with the surface are very robust and can cope with pathological cases
  such as sharp surface kinks. Notice that the search for intersection points
  does not involve any approximation and has only numerical inaccuracy which is
  set by default as 1 fm. Any surface can be combined with a (differently and
  variably oriented) crystal structure and/or (variable) grating vector.
  Surfaces can be faceted.

* *Energy dispersive elements*. Implemented are :meth:`crystals in dynamical
  diffraction <xrt.backends.raycing.materials.Crystal.get_amplitude>`,
  gratings (also with efficiency calculations), Fresnel zone plates,
  Bragg-Fresnel optics and :meth:`multilayers in dynamical diffraction
  <xrt.backends.raycing.materials.Multilayer.get_amplitude>`. Crystals can work
  in Bragg or Laue cases, in reflection or in transmission. The
  two-field polarization phenomena are fully preserved, also within the Darwin
  diffraction plateau, thus enabling the ray tracing of crystal-based phase
  retarders.

* *Materials*. The material properties are incorporated using :class:`three
  different tabulations <xrt.backends.raycing.materials.Material>` of the
  scattering factors, with differently wide and differently dense energy
  meshes. Refractive index and absorption coefficient are calculated from the
  scattering factors. Two-surface bodies, such as plates or refractive lenses,
  are treated with both refraction and absorption.

* *Multiple reflections*. xrt can trace multiple reflections in a single
  optical element. This is useful, for example in 'whispering gallery' optics
  or in Montel or Wolter mirrors.

* *Non-sequential optics*. xrt can trace non-sequential optics where different
  parts of the incoming beam meet different surfaces. Examples of such optics
  are :ref:`poly-capillaries<polycapillary>` and Wolter mirrors.

* *Singular optics*. xrt correctly propagates :ref:`vortex beams
  <test-Laguerre-Gaussian>`, which can be used for studying the creation of
  vortex beams by transmissive or reflective optics.

* *Global coordinate system*. The optical elements are positioned in a global
  coordinate system. This is convenient for modeling a real synchrotron
  beamline. The coordinates in this system can be directly taken from a CAD
  library. The optical surfaces are defined in their local systems for the
  user's convenience.

* *Beam categories*. xrt discriminates rays by several categories: `good`,
  `out`, `over` and `dead`. This distinction simplifies the adjustment of
  entrance and exit slits. An alarm is triggered if the fraction of dead rays
  exceeds a specified level.

* *Portability*. xrt runs on Windows and Unix-like platforms, wherever you can
  run python.

* *Examples*. xrt comes with many examples. See the galleries, the links are at
  the top bar.

* *Tests*. xrt comes with the tests of its several main aspects. See the folder
  `tests` and also this documentation for the tests of
  :ref:`undulators <mesh-methods>`, :ref:`optical elements <test_oes>`,
  :ref:`materials <test_materials>` and :ref:`wave propagation <test_waves>`.

Dependencies
------------

numpy, scipy and matplotlib are required. If you use OpenCL for calculations on
GPU or CPU, you need AMD/NVIDIA drivers, ``Intel CPU only OpenCL runtime``
(these are search key words), pytools and pyopencl. PyQt4 or PyQt5 are needed
for xrtQook. Spyder (as library of Spyder IDE) is highly recommended for nicer
view of xrtQook. OpenGL is required for xrtGlow.

See :ref:`detailed instructions for installing dependencies <instructions>`.

Get xrt
-------

xrt is available as source distribution from `pypi.python.org
<https://pypi.python.org/pypi/xrt>`_ and from `GitHub
<https://github.com/kklmn/xrt>`_. The distribution archive also includes tests
and examples. The complete documentation is available online at
`Read the Docs <http://xrt.readthedocs.io>`_ and offline as
`zip file at GitHub <https://github.com/kklmn/xrt-docs>`_.

Installation
------------

Unzip the .zip file into a suitable directory and use
`sys.path.append(path-to-xrt)` in your script. You can also install xrt to the
standard location by running ``python setup.py install`` from the directory
where you have unzipped the archive, which is less convenient if you try
different versions of xrt and/or different versions of python. Note that
python-64-bit is by ~20% faster than the 32-bit version (tested with
WinPython). Also consider :ref:`Speed tests <tests>` for making choice between
Windows and Linux and between Python 2 and Python 3.

Get help
--------

For getting help and/or reporting a bug please use `GitHub xrt Issues
<https://github.com/kklmn/xrt/issues>`_.

Citing xrt
----------

Please cite xrt as:
`K. Klementiev and R. Chernikov, "Powerful scriptable ray tracing package xrt",
Proc. SPIE 9209, Advances in Computational Methods for X-Ray Optics III,
92090A; doi:10.1117/12.2061400 <http://dx.doi.org/10.1117/12.2061400>`_.
`Online documentation at xrt.readthedocs.io;
doi:10.5281/zenodo.1252468 <https://doi.org/10.5281/zenodo.1252468>`_.

Acknowledgments
---------------

* Josep Nicolás and Jordi Juanhuix (synchrotron Alba) are acknowledged for
  discussion and for their Matlab codes used as examples at early stages of the
  project.

* Andrew Geondzhian and Victoria Kabanova (summer students at DESY) are
  acknowledged for their help in coding the classes of synchrotron sources.

* Rami Sankari and Alexei Preobrajenski (MAX IV Laboratory) are thanked for
  discussion, testing and comparing with external codes.

* Hasan Yavaş, Jozef Bednarčik, Dmitri Novikov and Alexey Zozulya (DESY Photon
  Science) are acknowledged for supplied cases.

* Hamed Tarawneh (MAX IV Laboratory) has initiated the custom field undulator
  project and supplied tables of magnetic field.

* Bernard Kozioziemski (LLNL) has pointed to the importance of considering
  the *total* absorption cross-section (not just photoelectric absorption) in
  the cases of light materials at high energy. He also did deep tests of the
  mosaic crystal model.

* Emilio Heredia (CLS) is thanked for valuable suggestions on GUI.

* Tim May (CLS) is acknowledged for inspiring the custom magnetic field
  calculation development, providing field tables and comparing the results
  with other codes.

* Louisa Pickworth (MAX IV Laboratory) has provided curves from other codes for
  testing reflectivity/transmittivity of multilayers.

"""

# ========Convention: note the difference from PEP8 for variables!=============
# Naming:
#   * classes MixedUpperCase
#   * varables lowerUpper _or_ lower
#   * functions and methods underscore_separated _or_ lower
# =============================================================================

from .version import __versioninfo__, __version__, __date__
__module__ = "xrt"
__author__ = \
    "Konstantin Klementiev (MAX IV Laboratory), " +\
    "Roman Chernikov (Canadian Light Source)"
__email__ = "konstantin DOT klementiev AT gmail DOT com, " +\
            "rchernikov AT gmail DOT com"
__license__ = "MIT license"

# __all__ = ['plotter', 'runner', 'multipro']
