[Tex/LaTex] Transparent shade using TikZ

colorshadingtikz-pgftransparency

I wonder whether it is possible to create a transparent shading effect (like the one below) without an exact specification of the fill color. This solution is good until I have to change the background to a non-solid fill (demonstrated by the yellow block). Can I create the (almost, I want to see the yellow line) same effect somehow with a transparent shade?

(Sorry for the brutal yellow, it is for demonstration purposes only.)

enter image description here

\documentclass{article}
\usepackage{tikz}

\begin{document}
\parindent0pt
  \null
  \definecolor{orange}{RGB}{233,77,16}

  \thispagestyle{empty}
  \vspace{-1cm}
  \vfill
  \hfil
  \begin{tikzpicture}[overlay]
    \coordinate (gNE)                       at (+0.501\paperwidth,+0.501\paperheight);
    \coordinate (gSW)                       at (-0.501\paperwidth,-0.501\paperheight);
    \coordinate (titleN)                at (+0.000\paperwidth,+0.300\paperheight);
    \coordinate (titleS)                at (+0.000\paperwidth,+0.100\paperheight);

    \fill [color=orange] (gSW) rectangle (gNE);
    \fill [color=yellow] (0.3\paperwidth,0.51\paperheight) rectangle (0.4\paperwidth,-0.5\paperheight);
    \shade [left color=black, right color=orange] (titleS -| gSW) rectangle (titleN -| gNE);
  \end{tikzpicture}
  \vfill

\end{document}

Best Answer

You can use path fading=east from the fadings library for this:

\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{fadings}

\begin{document}
\parindent0pt
  \null
  \definecolor{orange}{RGB}{233,77,16}

  \thispagestyle{empty}
  \vspace{-1cm}
  \vfill
  \hfil
  \begin{tikzpicture}[overlay]
    \coordinate (gNE)                       at (+0.501\paperwidth,+0.501\paperheight);
    \coordinate (gSW)                       at (-0.501\paperwidth,-0.501\paperheight);
    \coordinate (titleN)                at (+0.000\paperwidth,+0.300\paperheight);
    \coordinate (titleS)                at (+0.000\paperwidth,+0.100\paperheight);

    \fill [color=orange] (gSW) rectangle (gNE);
    \fill [color=yellow] (0.3\paperwidth,0.51\paperheight) rectangle (0.4\paperwidth,-0.5\paperheight);
    \fill [black, path fading=east] (titleS -| gSW) rectangle (titleN -| gNE);
  \end{tikzpicture}
  \vfill

\end{document}
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