PSTricks 图形中的颜色渐变填充

Question

考虑下面的图画：

\documentclass[
  a4paper,
  12pt
]{article}

\usepackage[utf8]{inputenc}
\usepackage[
  hmargin=2.4cm,
  vmargin=3cm
]{geometry}
\usepackage{rotating}
\usepackage{pstricks-add}

\newcommand*\forskel{350 140 div }
\newcommand*\udtag[2]{\rput(!10   249 140 div #1 \forskel mul add){\small #2}}
\newcommand*\pil[1]{  \rput(!11.5 249 140 div #1 \forskel mul add){\small $\rightarrow$}}
\newcommand*\destillering[1]{%
  % Ventiler og udtag.
  \psline(!4    2.8  #1 \forskel mul add)%
         (!4    1.8  #1 \forskel mul add)%
         (!4    2.3  #1 \forskel mul add)%
         (!5.3  2.3  #1 \forskel mul add)%
         (!5.3  2.65 #1 \forskel mul add)
  \psline(!5.15 2.5  #1 \forskel mul add)%
         (!5.15 2.8  #1 \forskel mul add)%
         (!5.95 2.8  #1 \forskel mul add)%
         (!5.95 2.5  #1 \forskel mul add)
  \psline(!5.8  2.65 #1 \forskel mul add)%
         (!5.8  2.3  #1 \forskel mul add)%
         (!6.3  2.3  #1 \forskel mul add)%
         (!6.3  2.65 #1 \forskel mul add)
  \psline(!6.15 2.5  #1 \forskel mul add)%
         (!6.15 2.8  #1 \forskel mul add)%
         (!6.95 2.8  #1 \forskel mul add)%
         (!6.95 2.5  #1 \forskel mul add)
  \psline(!6.8  2.65 #1 \forskel mul add)%
         (!6.8  2.3  #1 \forskel mul add)%
         (!7.4  2.3  #1 \forskel mul add)
  \psline(!   8.5       284 140 div #1       \forskel mul add)%
         (!   8.5       214 140 div #1 1 add \forskel mul add)
  \psarc(! 1144 140 div   2.3       #1       \forskel mul add){0.27142857}{180}{270}
  \psarc(! 1144 140 div   2.3       #1       \forskel mul add){0.77142857}{180}{270}
  \psline(!   7.9         2.3       #1       \forskel mul add)%
         (!   8.5         2.3       #1       \forskel mul add)
  \psline(!1144 140 div 284 140 div #1       \forskel mul add)%
         (!  12         284 140 div #1       \forskel mul add)
  \psline(!  12         214 140 div #1       \forskel mul add)%
         (!2861 350 div 214 140 div #1       \forskel mul add)
  % `Mellemventiler'.
  \psline(!3.5  470 140 div #1 \forskel mul add)%
         (!5.3  470 140 div #1 \forskel mul add)%
         (!5.3  519 140 div #1 \forskel mul add)
  \psline(!5.15 498 140 div #1 \forskel mul add)%
         (!5.15 540 140 div #1 \forskel mul add)%
         (!5.95 540 140 div #1 \forskel mul add)%
         (!5.95 498 140 div #1 \forskel mul add)
  \psline(!5.8  519 140 div #1 \forskel mul add)%
         (!5.8  470 140 div #1 \forskel mul add)%
         (!6.3  470 140 div #1 \forskel mul add)%
         (!6.3  519 140 div #1 \forskel mul add)
  \psline(!6.15 498 140 div #1 \forskel mul add)%
         (!6.15 540 140 div #1 \forskel mul add)%
         (!6.95 540 140 div #1 \forskel mul add)%
         (!6.95 498 140 div #1 \forskel mul add)
  \psline(!6.8  519 140 div #1 \forskel mul add)%
         (!6.8  470 140 div #1 \forskel mul add)%
         (!8.1  470 140 div #1 \forskel mul add)%
         (!8.1  392 140 div #1 \forskel mul add)%
}

\pagestyle{empty}

\begin{document}

\vfill
\begin{figure}[htbp]
 \centering
 \psset{unit=1cm}
  \begin{pspicture}(-1.02,0.3)(12,17)
    % Opvarmningsovn.
    \psline(0.7,4.7)(0.7,5)(3.3,5)(3.3,2.9)
    \psline(3.3,2.4)(3.3,2)(0.7,2)(0.7,4.2)
    \psline(-0.8,4.7)(2.3,4.7)
    \psline(-0.8,4.2)(2.3,4.2)
    \psarc(2.3,4){0.2}{270}{90}
    \psarc(2.3,4){0.7}{270}{90}
    \psline(2.3,3.8)(1.7,3.8)
    \psline(2.3,3.3)(1.7,3.3)
    \psarc(1.7,3.1){0.2}{90}{270}
    \psarc(1.7,3.1){0.7}{90}{270}
    \psline(1.7,2.9)(3.5,2.9)
    \psline(1.7,2.4)(3.5,2.4)
    \rput(2,1.75){\small Ovn}
    \rput(1.15,4.45){\small `Kold' råolie}
    \rput(-0.4,4.45){\small $\rightarrow$}
    % Tårnets indre samt udtag.
    \multido{\i=0+1}{5}{%
      \destillering{\i}%
      \pil{\i}%
    }
    \pil{6}
    \udtag{0}{Brændselsolie}
    \udtag{1}{Smøreolie}
    \udtag{2}{Dieselolie}
    \udtag{3}{Petroleum}
    \udtag{4}{Nafta}
    \udtag{6}{Gasser}
    % Tårnets ydre.
    \psline(  3.5,   2.9)%
           (! 3.5  179 140 div 6 \forskel mul add)%
           (! 5.75 179 140 div 6 \forskel mul add)
    \psarc(!  6.5  179 140 div 6 \forskel mul add){0.25}{90}{180}
    \psline(! 6.5  214 140 div 6 \forskel mul add)%
           (!12    214 140 div 6 \forskel mul add)
    \psarc(!  6.5  179 140 div 6 \forskel mul add){0.75}{90}{180}
    \psline(! 6.5  284 140 div 6 \forskel mul add)%
           (!12    284 140 div 6 \forskel mul add)
    \psline(! 6.25 179 140 div 6 \forskel mul add)%
           (! 8.5  179 140 div 6 \forskel mul add)%
           (! 8.5  284 140 div 5 \forskel mul add)%
%           (!12    284 140 div 5 \forskel mul add)
%    \psline(! 8.5  214 140 div 5 \forskel mul add)%
%           (!12    214 140 div 5 \forskel mul add)
    \psline(!8.5 284 140 div 5 \forskel mul add)%
           (!8.5 214 140 div 5 \forskel mul add)
    \psarc(6.5,1){0.25}{180}{270}
    \psline(6.5,0.75)(12,0.75)
    \psarc(6.5,1){0.75}{180}{270}
    \psline(6.5,0.25)(12,0.25)
    \psline(!8.5 214 140 div)(8.5,1)(6.25,1)
    \rput(9,0.5){\small Destillationsrester}
    \rput(11.5,0.5){\small $\rightarrow$}
    \psline(5.75,1)(3.5,1)(3.5,2.4)
  \end{pspicture}
\end{figure}
\vfill

\end{document}

我怎样才能逐渐给塔和管道上色，从底部的深红色开始，到顶部的浅黄色结束？

更新

在 Werner 的帮助下，我得到了以下结果：

\documentclass[
  a4paper,
  12pt
]{article}

\usepackage[utf8]{inputenc}
\usepackage[
  hmargin=2.4cm,
  vmargin=3cm
]{geometry}
\usepackage{rotating}
\usepackage{
  pst-slpe,
  pstricks-add
}

\newcommand*\forskel{350 140 div }
\newcommand*\udtag[2]{\rput(!10   249 140 div #1 \forskel mul add){\small #2}}
\newcommand*\pil[1]{  \rput(!11.5 249 140 div #1 \forskel mul add){\small $\rightarrow$}}
\newcommand*\destillering[1]{%
  % Ventiler.
  \psline(!4    2.8  #1 \forskel mul add)%
         (!4    1.8  #1 \forskel mul add)%
         (!4    2.3  #1 \forskel mul add)%
         (!5.3  2.3  #1 \forskel mul add)%
         (!5.3  2.65 #1 \forskel mul add)
  \psline(!5.15 2.5  #1 \forskel mul add)%
         (!5.15 2.8  #1 \forskel mul add)%
         (!5.95 2.8  #1 \forskel mul add)%
         (!5.95 2.5  #1 \forskel mul add)
  \psline(!5.8  2.65 #1 \forskel mul add)%
         (!5.8  2.3  #1 \forskel mul add)%
         (!6.3  2.3  #1 \forskel mul add)%
         (!6.3  2.65 #1 \forskel mul add)
  \psline(!6.15 2.5  #1 \forskel mul add)%
         (!6.15 2.8  #1 \forskel mul add)%
         (!6.95 2.8  #1 \forskel mul add)%
         (!6.95 2.5  #1 \forskel mul add)
  \psline(!6.8  2.65 #1 \forskel mul add)%
         (!6.8  2.3  #1 \forskel mul add)%
         (!7.4  2.3  #1 \forskel mul add)
  \psline(!   8.5       284 140 div #1       \forskel mul add)%
         (!   8.5       214 140 div #1 1 add \forskel mul add)
  % `Mellemventiler'.
  \psline(!3.5  470 140 div #1 \forskel mul add)%
         (!5.3  470 140 div #1 \forskel mul add)%
         (!5.3  519 140 div #1 \forskel mul add)
  \psline(!5.15 498 140 div #1 \forskel mul add)%
         (!5.15 540 140 div #1 \forskel mul add)%
         (!5.95 540 140 div #1 \forskel mul add)%
         (!5.95 498 140 div #1 \forskel mul add)
  \psline(!5.8  519 140 div #1 \forskel mul add)%
         (!5.8  470 140 div #1 \forskel mul add)%
         (!6.3  470 140 div #1 \forskel mul add)%
         (!6.3  519 140 div #1 \forskel mul add)
  \psline(!6.15 498 140 div #1 \forskel mul add)%
         (!6.15 540 140 div #1 \forskel mul add)%
         (!6.95 540 140 div #1 \forskel mul add)%
         (!6.95 498 140 div #1 \forskel mul add)
  \psline(!6.8  519 140 div #1 \forskel mul add)%
         (!6.8  470 140 div #1 \forskel mul add)%
         (!8.1  470 140 div #1 \forskel mul add)%
         (!8.1  392 140 div #1 \forskel mul add)%
  % Udtag.
  \psarc(! 1144 140 div   2.3       #1       \forskel mul add){0.27142857}{180}{270}
  \psarc(! 1144 140 div   2.3       #1       \forskel mul add){0.77142857}{180}{270}
  \psline(!   7.9         2.3       #1       \forskel mul add)%
         (!   8.5         2.3       #1       \forskel mul add)
  \psline(!1144 140 div 284 140 div #1       \forskel mul add)%
         (!  12         284 140 div #1       \forskel mul add)
  \psline(!  12         214 140 div #1       \forskel mul add)%
         (!2861 350 div 214 140 div #1       \forskel mul add)
}

\pagestyle{empty}

\begin{document}

\vfill
\begin{center}
 \psset{
   unit=1cm
 }
  \begin{pspicture}(-0.8,0.25)(12,17)
    % Farvegraduering.
   {\psset{
      linestyle = none,
      slopeangle = 90,
      fillstyle = slope,
      slopebegin = red!90!black,
      slopeend = yellow
    }
      \psframe[
        slopesteps = 50
      ](0.7,2)(3.3,5)
      \pscustom[
        slopesteps = 200
      ]{
        \multido{\iA = 0+1}{5}{%
          \psline(! 8.5 284 140 div \iA\space \forskel mul add)%
                 (!12   284 140 div \iA\space \forskel mul add)%
                 (!12   214 140 div \iA\space \forskel mul add)%
                 (! 8.5 214 140 div \iA\space \forskel mul add)%
        }
        \psline(8.5,1)(6.3,1)
        \psarc(6.5,1){0.25}{180}{270}
        \psline(6.5,0.75)(12,0.75)(12,0.25)(6.5,0.25)
        \psarcn(6.5,1){0.75}{270}{180}
        \psline(5.75,1)(3.5,1)(3.5,2.4)(3.5,16.3)(5.75,16.3)
        \psarc(6.5,16.3){0.75}{90}{180}
        \psline(6.5,17.05)(12,17.05)(12,16.55)(6.5,16.55)
        \psarc(6.5,16.3){0.25}{90}{180}
        \psline(6.5,16.3)(8.5,16.3)
      }
   }
   {\psset{
      linestyle = none,
      slopeangle = 90,
      fillstyle = slope,
      slopebegin = red!80!yellow,
      slopeend = blue!50!black
    }
      \pscustom[
        slopesteps = 50
      ]{
        \psline(-0.8,4.2)(2.3,4.2)
        \psarc(2.3,4){0.2}{-90}{90}
        \psline(2.3,3.8)(1.7,3.8)
        \psarcn(1.7,3.1){0.7}{-90}{90}
        \psline(1.7,2.4)(3.5,2.4)(3.5,2.9)(1.7,2.9)
        \psarc(1.7,3.1){0.2}{90}{-90}
        \psline(1.7,3.3)(2.3,3.3)
        \psarcn(2.3,4){0.7}{90}{-90}
        \psline(2.3,4.7)(-0.8,4.7)
      }
   }
    % Opvarmningsovn.
    \psline(0.7,4.7)(0.7,5)(3.3,5)(3.3,2.9)
    \psline(3.3,2.4)(3.3,2)(0.7,2)(0.7,4.2)
    \psline(-0.8,4.7)(2.3,4.7)
    \psline(-0.8,4.2)(2.3,4.2)
    \psarc(2.3,4){0.2}{270}{90}
    \psarc(2.3,4){0.7}{270}{90}
    \psline(2.3,3.8)(1.7,3.8)
    \psline(2.3,3.3)(1.7,3.3)
    \psarc(1.7,3.1){0.2}{90}{270}
    \psarc(1.7,3.1){0.7}{90}{270}
    \psline(1.7,2.9)(3.5,2.9)
    \psline(1.7,2.4)(3.5,2.4)
    \rput(2,1.75){\small Ovn}
    \rput(1.15,4.45){\small `Kold' råolie}
    \rput(-0.4,4.45){\small $\rightarrow$}
    % Tårnets indre samt udtag.
    \multido{\iB = 0+1}{5}{%
      \destillering{\iB}%
      \pil{\iB}%
    }
    \pil{6}
    \udtag{0}{Brændselsolie}
    \udtag{1}{Smøreolie}
    \udtag{2}{Dieselolie}
    \udtag{3}{Petroleum}
    \udtag{4}{Nafta}
    \udtag{6}{Gasser}
    % Tårnets ydre.
    \psline(  3.5,   2.9)%
           (! 3.5  179 140 div 6 \forskel mul add)%
           (! 5.75 179 140 div 6 \forskel mul add)
    \psarc(!  6.5  179 140 div 6 \forskel mul add){0.25}{90}{180}
    \psline(! 6.5  214 140 div 6 \forskel mul add)%
           (!12    214 140 div 6 \forskel mul add)
    \psarc(!  6.5  179 140 div 6 \forskel mul add){0.75}{90}{180}
    \psline(! 6.5  284 140 div 6 \forskel mul add)%
           (!12    284 140 div 6 \forskel mul add)
    \psline(! 6.25 179 140 div 6 \forskel mul add)%
           (! 8.5  179 140 div 6 \forskel mul add)%
           (! 8.5  284 140 div 5 \forskel mul add)%
%           (!12    284 140 div 5 \forskel mul add)
%    \psline(! 8.5  214 140 div 5 \forskel mul add)%
%           (!12    214 140 div 5 \forskel mul add)
    \psline(!8.5 284 140 div 5 \forskel mul add)%
           (!8.5 214 140 div 5 \forskel mul add)
    % Nederste udtag.
    \psarc(6.5,1){0.25}{180}{270}
    \psline(6.5,0.75)(12,0.75)
    \psline(12,0.25)(6.5,0.25)
    \psarc(6.5,1){0.75}{180}{270}
    \psline(!8.5 214 140 div)(8.5,1)(6.25,1)
    \rput(9,0.5){\small Destillationsrester}
    \rput(11.5,0.5){\small $\rightarrow$}
    \psline(5.75,1)(3.5,1)(3.5,2.4)
  \end{pspicture}
\end{center}
\vfill

\end{document}

Answer 1

“最简单”的方法是创建一个\pscustom包含整个塔+管道结构的路径，并使用pst-slpe的slope填充。

下面我仅显示自定义路径的一部分，省略了一些管道。但是，过程是相同的。此外，填充实际上是纯红色，并以 90 度角应用了淡入淡出：

\documentclass[
  a4paper,
  12pt
]{article}

\usepackage[utf8]{inputenc}
\usepackage[
  hmargin=2.4cm,
  vmargin=3cm
]{geometry}
\usepackage{rotating}
\usepackage{pstricks-add,pst-slpe}

\newcommand*\forskel{350 140 div }
\newcommand*\udtag[2]{\rput(!10   249 140 div #1 \forskel mul add){\small #2}}
\newcommand*\pil[1]{  \rput(!11.5 249 140 div #1 \forskel mul add){\small $\rightarrow$}}
\newcommand*\destillering[1]{%
  % Ventiler og udtag.
  \psline(!4    2.8  #1 \forskel mul add)%
         (!4    1.8  #1 \forskel mul add)%
         (!4    2.3  #1 \forskel mul add)%
         (!5.3  2.3  #1 \forskel mul add)%
         (!5.3  2.65 #1 \forskel mul add)
  \psline(!5.15 2.5  #1 \forskel mul add)%
         (!5.15 2.8  #1 \forskel mul add)%
         (!5.95 2.8  #1 \forskel mul add)%
         (!5.95 2.5  #1 \forskel mul add)
  \psline(!5.8  2.65 #1 \forskel mul add)%
         (!5.8  2.3  #1 \forskel mul add)%
         (!6.3  2.3  #1 \forskel mul add)%
         (!6.3  2.65 #1 \forskel mul add)
  \psline(!6.15 2.5  #1 \forskel mul add)%
         (!6.15 2.8  #1 \forskel mul add)%
         (!6.95 2.8  #1 \forskel mul add)%
         (!6.95 2.5  #1 \forskel mul add)
  \psline(!6.8  2.65 #1 \forskel mul add)%
         (!6.8  2.3  #1 \forskel mul add)%
         (!7.4  2.3  #1 \forskel mul add)
  \psline(!   8.5       284 140 div #1       \forskel mul add)%
         (!   8.5       214 140 div #1 1 add \forskel mul add)
  \psarc(! 1144 140 div   2.3       #1       \forskel mul add){0.27142857}{180}{270}
  \psarc(! 1144 140 div   2.3       #1       \forskel mul add){0.77142857}{180}{270}
  \psline(!   7.9         2.3       #1       \forskel mul add)%
         (!   8.5         2.3       #1       \forskel mul add)
  \psline(!1144 140 div 284 140 div #1       \forskel mul add)%
         (!  12         284 140 div #1       \forskel mul add)
  \psline(!  12         214 140 div #1       \forskel mul add)%
         (!2861 350 div 214 140 div #1       \forskel mul add)
  % `Mellemventiler'.
  \psline(!3.5  470 140 div #1 \forskel mul add)%
         (!5.3  470 140 div #1 \forskel mul add)%
         (!5.3  519 140 div #1 \forskel mul add)
  \psline(!5.15 498 140 div #1 \forskel mul add)%
         (!5.15 540 140 div #1 \forskel mul add)%
         (!5.95 540 140 div #1 \forskel mul add)%
         (!5.95 498 140 div #1 \forskel mul add)
  \psline(!5.8  519 140 div #1 \forskel mul add)%
         (!5.8  470 140 div #1 \forskel mul add)%
         (!6.3  470 140 div #1 \forskel mul add)%
         (!6.3  519 140 div #1 \forskel mul add)
  \psline(!6.15 498 140 div #1 \forskel mul add)%
         (!6.15 540 140 div #1 \forskel mul add)%
         (!6.95 540 140 div #1 \forskel mul add)%
         (!6.95 498 140 div #1 \forskel mul add)
  \psline(!6.8  519 140 div #1 \forskel mul add)%
         (!6.8  470 140 div #1 \forskel mul add)%
         (!8.1  470 140 div #1 \forskel mul add)%
         (!8.1  392 140 div #1 \forskel mul add)%
}

\pagestyle{empty}

\begin{document}

\vfill
\begin{figure}[htbp]
 \centering
 \psset{unit=1cm}
  \begin{pspicture}(-1.02,0.3)(12,17)
    % Opvarmningsovn.
    %\psgrid
    \psframe[linestyle=none,slopeangle=90,slopesteps=50,
      fillstyle=slope,slopebegin=red,slopeend=yellow
      ](0.7,2)(3.3,5)% Ovn
    \pscustom[linestyle=none,slopeangle=90,slopesteps=200,
      fillstyle=slope,slopebegin=red,slopeend=yellow
      ]{
      \psline(12,0.25)(6.5,0.25)
      \psarcn(6.5,1){0.75}{270}{180}
      \psline(5.8,1)(3.5,1)(3.5,2.4)(1.7,2.4)
      \psarcn(1.7,3.1){0.7}{-90}{90}
      \psline(1.7,3.8)(2.3,3.8)
      \psarc(2.3,4){0.2}{-90}{90}
      \psline(2.3,4.2)(-0.8,4.2)(-0.8,4.7)(2.3,4.7)
      \psarcn(2.3,4){0.7}{90}{-90}
      \psline(2.3,3.3)(1.7,3.3)
      \psarc(1.7,3.1){0.2}{90}{-90}
      \psline(1.7,2.9)(3.5,2.9)(3.5,16.3)(8.5,16.3)
        (8.5,12)(12,12)(12,11.5)(8.5,11.5)% Nafta
        (8.5,9.5)(12,9.5)(12,9)(8.5,9)% Petroleum
        (8.5,7)(12,7)(12,6.5)(8.5,6.5)% Dieselolie
        (8.5,4.5)(12,4.5)(12,4)(8.5,4)% Smoreolie
        (8.5,2)(12,2)(12,1.5)(8.5,1.5)% Braendselolie
        (8.5,1)(6.3,1)
      \psarc(6.5,1){0.25}{180}{270}
      \psline(6.5,0.75)(12,0.75)(12,0.25)
    }
    \psline(0.7,4.7)(0.7,5)(3.3,5)(3.3,2.9)
    \psline(3.3,2.4)(3.3,2)(0.7,2)(0.7,4.2)
    \psline(-0.8,4.7)(2.3,4.7)
    \psline(-0.8,4.2)(2.3,4.2)
    \psarc(2.3,4){0.2}{270}{90}
    \psarc(2.3,4){0.7}{270}{90}
    \psline(2.3,3.8)(1.7,3.8)
    \psline(2.3,3.3)(1.7,3.3)
    \psarc(1.7,3.1){0.2}{90}{270}
    \psarc(1.7,3.1){0.7}{90}{270}
    \psline(1.7,2.9)(3.5,2.9)
    \psline(1.7,2.4)(3.5,2.4)
    \rput(2,1.75){\small Ovn}
    \rput(1.15,4.45){\small `Kold' råolie}
    \rput(-0.4,4.45){\small $\rightarrow$}
    % Tårnets indre samt udtag.
    \multido{\i=0+1}{5}{%
      \destillering{\i}%
      \pil{\i}%
    }
    \pil{6}
    \udtag{0}{Brændselsolie}
    \udtag{1}{Smøreolie}
    \udtag{2}{Dieselolie}
    \udtag{3}{Petroleum}
    \udtag{4}{Nafta}
    \udtag{6}{Gasser}
    % Tårnets ydre.
    \psline(  3.5,   2.9)%
           (! 3.5  179 140 div 6 \forskel mul add)%
           (! 5.75 179 140 div 6 \forskel mul add)
    \psarc(!  6.5  179 140 div 6 \forskel mul add){0.25}{90}{180}
    \psline(! 6.5  214 140 div 6 \forskel mul add)%
           (!12    214 140 div 6 \forskel mul add)
    \psarc(!  6.5  179 140 div 6 \forskel mul add){0.75}{90}{180}
    \psline(! 6.5  284 140 div 6 \forskel mul add)%
           (!12    284 140 div 6 \forskel mul add)
    \psline(! 6.25 179 140 div 6 \forskel mul add)%
           (! 8.5  179 140 div 6 \forskel mul add)%
           (! 8.5  284 140 div 5 \forskel mul add)%
%           (!12    284 140 div 5 \forskel mul add)
%    \psline(! 8.5  214 140 div 5 \forskel mul add)%
%           (!12    214 140 div 5 \forskel mul add)
    \psline(!8.5 284 140 div 5 \forskel mul add)%
           (!8.5 214 140 div 5 \forskel mul add)
    \psarc(6.5,1){0.25}{180}{270}
    \psline(6.5,0.75)(12,0.75)
    \psarc(6.5,1){0.75}{180}{270}
    \psline(6.5,0.25)(12,0.25)
    \psline(!8.5 214 140 div)(8.5,1)(6.25,1)
    \rput(9,0.5){\small Destillationsrester}
    \rput(11.5,0.5){\small $\rightarrow$}
    \psline(5.75,1)(3.5,1)(3.5,2.4)
  \end{pspicture}
\end{figure}
\vfill

\end{document}

您首先绘制填充，然后按原样覆盖其余结构。 沿侧管的对齐不是 100%，但那是因为我不完全了解它们在混合坐标中绘制的位置。

我增加了用于定义斜率颜色的步数。