%% -*- mode: latex; mode: reftex; mode: flyspell; coding: utf-8; tex-command: "pdflatex.sh" -*-

% Any copyright is dedicated to the Public Domain.
% https://creativecommons.org/publicdomain/zero/1.0/

% Written by Francois Fleuret <francois@fleuret.org>

\documentclass[11pt,a4paper,twoside]{article}
\usepackage[a4paper,top=2.5cm,bottom=2cm,left=2.5cm,right=2.5cm]{geometry}
\usepackage{amsmath,amssymb,dsfont}
\usepackage[pdftex]{graphicx}
\usepackage[colorlinks=true,linkcolor=blue,urlcolor=blue,citecolor=blue]{hyperref}
\usepackage{tikz}
\usetikzlibrary{arrows.meta}
\usepackage{cmbright}

\begin{document}

\definecolor{green}{rgb}{0.0,0.50,0.0}
\tikzset{>={Straight Barb[angle'=80,scale=1.1]}}

\begin{tikzpicture}

\draw[->] (0, 0) -- ++(0, 2);
\draw[->] (0, 0) -- ++(2.5, 0.6);
\draw[->] (0, 0) -- ++(3, 0) node[midway,below,yshift=-0.5em] {Original space ${\cal X}$};

\draw[fill=green!50,draw=none,shift={(0.2, 0.7)},scale=0.5]
  (0, 0) to[out=20,in=140] (1.5, -0.2) to [out=60,in=160]
  (5, 0.5) to[out=130,in=60]
  cycle;

\shade[thin,left color=green!10,right color=green!50,draw=none,shift={(0.2, 0.7)},scale=0.5]
  (0, 0) to[out=10,in=140] (3.3, -0.8) to [out=60,in=190] (5, 0.5) to[out=130,in=60] cycle;

  \draw[->] (4.8, 0.8) -- ++(0, 2);
  \draw[->] (4.8, 0.8) -- ++(2, 0) node[midway,below,yshift=-0.5em] {Latent space ${\cal F}$};

  \draw[thin,fill=green!30,draw=none,shift={(5.4, 1.1)},rotate=20]
    (0, 0) -- (1, 0) -- (1, 1) -- (0, 1) -- cycle;

  \draw[thick,->,red]
    (1.5, 1.3) to [out=55,in=150] node[midway,above,xshift=6pt,yshift=2pt] {$f$} (5.7, 2);

  \draw[thick,->,blue] (1.5, 1.3) ++(4.03, 0.3) to [out=150,in=55]
    node[midway,below,xshift=2pt,yshift=-2pt] {$g$} ++(-3.6, -0.5);

\end{tikzpicture}

\end{document}
