Draw a truncated pyramid with a square base












9















I want to draw a truncated pyramid that is suspended on a rope, and submersed inside water in a cylinder.



  documentclass{standalone}
usepackage{tikz}
usetikzlibrary{patterns}
begin{document}
begin{tikzpicture}
draw[gray!66](0,1) ellipse (2cm and 1cm);
draw(0,2) ellipse (2cm and 1cm);
draw(0,-3) ellipse (2cm and 1cm);
draw(2,-3)--(2,2);
draw(-2,-3)--(-2,2);

fill[pattern=north west lines](-1,4.4) rectangle (1,4.75);
draw(-1,4.4)--(1,4.4);
draw(0,4.4)--(0,-1);
end{tikzpicture}
end{document}


Enter image description here



Enter image description here










share|improve this question





























    9















    I want to draw a truncated pyramid that is suspended on a rope, and submersed inside water in a cylinder.



      documentclass{standalone}
    usepackage{tikz}
    usetikzlibrary{patterns}
    begin{document}
    begin{tikzpicture}
    draw[gray!66](0,1) ellipse (2cm and 1cm);
    draw(0,2) ellipse (2cm and 1cm);
    draw(0,-3) ellipse (2cm and 1cm);
    draw(2,-3)--(2,2);
    draw(-2,-3)--(-2,2);

    fill[pattern=north west lines](-1,4.4) rectangle (1,4.75);
    draw(-1,4.4)--(1,4.4);
    draw(0,4.4)--(0,-1);
    end{tikzpicture}
    end{document}


    Enter image description here



    Enter image description here










    share|improve this question



























      9












      9








      9








      I want to draw a truncated pyramid that is suspended on a rope, and submersed inside water in a cylinder.



        documentclass{standalone}
      usepackage{tikz}
      usetikzlibrary{patterns}
      begin{document}
      begin{tikzpicture}
      draw[gray!66](0,1) ellipse (2cm and 1cm);
      draw(0,2) ellipse (2cm and 1cm);
      draw(0,-3) ellipse (2cm and 1cm);
      draw(2,-3)--(2,2);
      draw(-2,-3)--(-2,2);

      fill[pattern=north west lines](-1,4.4) rectangle (1,4.75);
      draw(-1,4.4)--(1,4.4);
      draw(0,4.4)--(0,-1);
      end{tikzpicture}
      end{document}


      Enter image description here



      Enter image description here










      share|improve this question
















      I want to draw a truncated pyramid that is suspended on a rope, and submersed inside water in a cylinder.



        documentclass{standalone}
      usepackage{tikz}
      usetikzlibrary{patterns}
      begin{document}
      begin{tikzpicture}
      draw[gray!66](0,1) ellipse (2cm and 1cm);
      draw(0,2) ellipse (2cm and 1cm);
      draw(0,-3) ellipse (2cm and 1cm);
      draw(2,-3)--(2,2);
      draw(-2,-3)--(-2,2);

      fill[pattern=north west lines](-1,4.4) rectangle (1,4.75);
      draw(-1,4.4)--(1,4.4);
      draw(0,4.4)--(0,-1);
      end{tikzpicture}
      end{document}


      Enter image description here



      Enter image description here







      tikz-pgf






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Feb 4 at 14:46









      Peter Mortensen

      55037




      55037










      asked Feb 4 at 5:41









      ThumboltThumbolt

      1,509821




      1,509821






















          1 Answer
          1






          active

          oldest

          votes


















          15














          I'd use 3d coordinates for that.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{0.5}
          pgfmathsetmacro{zpyr}{3.5}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{whpyr}{wpyr-(hwater-zpyr)*wpyr/hpyr} % width of pyramid at water level
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          begin{scope}
          clip (-whpyr/2,-whpyr/2,hwater)
          -- (whpyr/2,-whpyr/2,hwater) -- (whpyr/2,whpyr/2,hwater)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,hwater)
          [reverseclip];
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},hwater);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},hwater)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          end{tikzpicture}
          end{document}


          enter image description here



          And this is an animation for Christian Hupfer with corrections due to @circumscribe.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          foreach Z in {0,10,...,350}
          {tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{1.2}
          pgfmathsetmacro{zpyr}{2.8+0.8*cos(Z)}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{deltahmax}{(wpyr^2/(pi*rcyl^2))*(hpyr-hremoved^3/hpyr^2)/3}
          pgfmathsetmacro{waterlevel}{hwater+ifthenelse(zpyr<hwater,1,0)*deltahmax*
          ifthenelse(zpyr>hwater-hpyr+hremoved,
          1-((zpyr-hwater+hpyr-hremoved)/(hpyr-hremoved))^3,1)}
          %typeout{deltahmax=deltahmax,waterlevel=waterlevel,zpyr=zpyr,hwater=hwater}
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          pgfmathsetmacro{whpyr}{wpyr-(waterlevel-zpyr)*wpyr/hpyr} % width of pyramid at water level
          begin{scope}
          pgfmathtruncatemacro{itest}{sign(-(waterlevel-zpyr)+(hpyr-hremoved))}
          ifnumitest=1
          clip (-whpyr/2,-whpyr/2,waterlevel)
          -- (whpyr/2,-whpyr/2,waterlevel) -- (whpyr/2,whpyr/2,waterlevel)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,waterlevel)
          [reverseclip];
          fi
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          % node[anchor=north west,tdplot_screen_coords,align=right]
          % at (1,7.75){waterlevel\ zpyr};
          end{tikzpicture}}
          end{document}


          enter image description here






          share|improve this answer


























          • The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

            – Thumbolt
            Feb 4 at 6:28






          • 3





            Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

            – user31729
            Feb 4 at 9:28






          • 1





            @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

            – Servaes
            Feb 4 at 12:09






          • 2





            @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

            – marmot
            Feb 4 at 15:31






          • 1





            @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

            – Circumscribe
            Feb 6 at 15:31












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          1 Answer
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          1 Answer
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          active

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          15














          I'd use 3d coordinates for that.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{0.5}
          pgfmathsetmacro{zpyr}{3.5}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{whpyr}{wpyr-(hwater-zpyr)*wpyr/hpyr} % width of pyramid at water level
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          begin{scope}
          clip (-whpyr/2,-whpyr/2,hwater)
          -- (whpyr/2,-whpyr/2,hwater) -- (whpyr/2,whpyr/2,hwater)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,hwater)
          [reverseclip];
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},hwater);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},hwater)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          end{tikzpicture}
          end{document}


          enter image description here



          And this is an animation for Christian Hupfer with corrections due to @circumscribe.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          foreach Z in {0,10,...,350}
          {tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{1.2}
          pgfmathsetmacro{zpyr}{2.8+0.8*cos(Z)}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{deltahmax}{(wpyr^2/(pi*rcyl^2))*(hpyr-hremoved^3/hpyr^2)/3}
          pgfmathsetmacro{waterlevel}{hwater+ifthenelse(zpyr<hwater,1,0)*deltahmax*
          ifthenelse(zpyr>hwater-hpyr+hremoved,
          1-((zpyr-hwater+hpyr-hremoved)/(hpyr-hremoved))^3,1)}
          %typeout{deltahmax=deltahmax,waterlevel=waterlevel,zpyr=zpyr,hwater=hwater}
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          pgfmathsetmacro{whpyr}{wpyr-(waterlevel-zpyr)*wpyr/hpyr} % width of pyramid at water level
          begin{scope}
          pgfmathtruncatemacro{itest}{sign(-(waterlevel-zpyr)+(hpyr-hremoved))}
          ifnumitest=1
          clip (-whpyr/2,-whpyr/2,waterlevel)
          -- (whpyr/2,-whpyr/2,waterlevel) -- (whpyr/2,whpyr/2,waterlevel)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,waterlevel)
          [reverseclip];
          fi
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          % node[anchor=north west,tdplot_screen_coords,align=right]
          % at (1,7.75){waterlevel\ zpyr};
          end{tikzpicture}}
          end{document}


          enter image description here






          share|improve this answer


























          • The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

            – Thumbolt
            Feb 4 at 6:28






          • 3





            Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

            – user31729
            Feb 4 at 9:28






          • 1





            @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

            – Servaes
            Feb 4 at 12:09






          • 2





            @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

            – marmot
            Feb 4 at 15:31






          • 1





            @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

            – Circumscribe
            Feb 6 at 15:31
















          15














          I'd use 3d coordinates for that.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{0.5}
          pgfmathsetmacro{zpyr}{3.5}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{whpyr}{wpyr-(hwater-zpyr)*wpyr/hpyr} % width of pyramid at water level
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          begin{scope}
          clip (-whpyr/2,-whpyr/2,hwater)
          -- (whpyr/2,-whpyr/2,hwater) -- (whpyr/2,whpyr/2,hwater)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,hwater)
          [reverseclip];
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},hwater);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},hwater)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          end{tikzpicture}
          end{document}


          enter image description here



          And this is an animation for Christian Hupfer with corrections due to @circumscribe.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          foreach Z in {0,10,...,350}
          {tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{1.2}
          pgfmathsetmacro{zpyr}{2.8+0.8*cos(Z)}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{deltahmax}{(wpyr^2/(pi*rcyl^2))*(hpyr-hremoved^3/hpyr^2)/3}
          pgfmathsetmacro{waterlevel}{hwater+ifthenelse(zpyr<hwater,1,0)*deltahmax*
          ifthenelse(zpyr>hwater-hpyr+hremoved,
          1-((zpyr-hwater+hpyr-hremoved)/(hpyr-hremoved))^3,1)}
          %typeout{deltahmax=deltahmax,waterlevel=waterlevel,zpyr=zpyr,hwater=hwater}
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          pgfmathsetmacro{whpyr}{wpyr-(waterlevel-zpyr)*wpyr/hpyr} % width of pyramid at water level
          begin{scope}
          pgfmathtruncatemacro{itest}{sign(-(waterlevel-zpyr)+(hpyr-hremoved))}
          ifnumitest=1
          clip (-whpyr/2,-whpyr/2,waterlevel)
          -- (whpyr/2,-whpyr/2,waterlevel) -- (whpyr/2,whpyr/2,waterlevel)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,waterlevel)
          [reverseclip];
          fi
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          % node[anchor=north west,tdplot_screen_coords,align=right]
          % at (1,7.75){waterlevel\ zpyr};
          end{tikzpicture}}
          end{document}


          enter image description here






          share|improve this answer


























          • The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

            – Thumbolt
            Feb 4 at 6:28






          • 3





            Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

            – user31729
            Feb 4 at 9:28






          • 1





            @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

            – Servaes
            Feb 4 at 12:09






          • 2





            @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

            – marmot
            Feb 4 at 15:31






          • 1





            @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

            – Circumscribe
            Feb 6 at 15:31














          15












          15








          15







          I'd use 3d coordinates for that.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{0.5}
          pgfmathsetmacro{zpyr}{3.5}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{whpyr}{wpyr-(hwater-zpyr)*wpyr/hpyr} % width of pyramid at water level
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          begin{scope}
          clip (-whpyr/2,-whpyr/2,hwater)
          -- (whpyr/2,-whpyr/2,hwater) -- (whpyr/2,whpyr/2,hwater)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,hwater)
          [reverseclip];
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},hwater);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},hwater)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          end{tikzpicture}
          end{document}


          enter image description here



          And this is an animation for Christian Hupfer with corrections due to @circumscribe.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          foreach Z in {0,10,...,350}
          {tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{1.2}
          pgfmathsetmacro{zpyr}{2.8+0.8*cos(Z)}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{deltahmax}{(wpyr^2/(pi*rcyl^2))*(hpyr-hremoved^3/hpyr^2)/3}
          pgfmathsetmacro{waterlevel}{hwater+ifthenelse(zpyr<hwater,1,0)*deltahmax*
          ifthenelse(zpyr>hwater-hpyr+hremoved,
          1-((zpyr-hwater+hpyr-hremoved)/(hpyr-hremoved))^3,1)}
          %typeout{deltahmax=deltahmax,waterlevel=waterlevel,zpyr=zpyr,hwater=hwater}
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          pgfmathsetmacro{whpyr}{wpyr-(waterlevel-zpyr)*wpyr/hpyr} % width of pyramid at water level
          begin{scope}
          pgfmathtruncatemacro{itest}{sign(-(waterlevel-zpyr)+(hpyr-hremoved))}
          ifnumitest=1
          clip (-whpyr/2,-whpyr/2,waterlevel)
          -- (whpyr/2,-whpyr/2,waterlevel) -- (whpyr/2,whpyr/2,waterlevel)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,waterlevel)
          [reverseclip];
          fi
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          % node[anchor=north west,tdplot_screen_coords,align=right]
          % at (1,7.75){waterlevel\ zpyr};
          end{tikzpicture}}
          end{document}


          enter image description here






          share|improve this answer















          I'd use 3d coordinates for that.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{0.5}
          pgfmathsetmacro{zpyr}{3.5}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{whpyr}{wpyr-(hwater-zpyr)*wpyr/hpyr} % width of pyramid at water level
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          begin{scope}
          clip (-whpyr/2,-whpyr/2,hwater)
          -- (whpyr/2,-whpyr/2,hwater) -- (whpyr/2,whpyr/2,hwater)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,hwater)
          [reverseclip];
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},hwater);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},hwater)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          end{tikzpicture}
          end{document}


          enter image description here



          And this is an animation for Christian Hupfer with corrections due to @circumscribe.



          documentclass[tikz,border=3.14mm]{standalone}
          usepackage{tikz-3dplot}
          usetikzlibrary{patterns}
          % https://tex.stackexchange.com/a/12033/121799
          tikzset{reverseclip/.style={insert path={(current bounding box.north
          east) rectangle (current bounding box.south west)}}}
          begin{document}
          foreach Z in {0,10,...,350}
          {tdplotsetmaincoords{70}{30}
          begin{tikzpicture}[tdplot_main_coords,font=sffamily,line join=bevel]
          pgfmathsetmacro{rcyl}{2}
          pgfmathsetmacro{hcyl}{5}
          pgfmathsetmacro{hpyr}{2.5}
          pgfmathsetmacro{hremoved}{1.2}
          pgfmathsetmacro{zpyr}{2.8+0.8*cos(Z)}
          pgfmathsetmacro{wpyr}{1.5}
          pgfmathsetmacro{wtop}{hremoved*wpyr/hpyr}
          pgfmathsetmacro{hwater}{4}
          pgfmathsetmacro{deltahmax}{(wpyr^2/(pi*rcyl^2))*(hpyr-hremoved^3/hpyr^2)/3}
          pgfmathsetmacro{waterlevel}{hwater+ifthenelse(zpyr<hwater,1,0)*deltahmax*
          ifthenelse(zpyr>hwater-hpyr+hremoved,
          1-((zpyr-hwater+hpyr-hremoved)/(hpyr-hremoved))^3,1)}
          %typeout{deltahmax=deltahmax,waterlevel=waterlevel,zpyr=zpyr,hwater=hwater}
          fill[tdplot_screen_coords,pattern=north west lines] (-1,7.4) rectangle (1,7.75);
          draw[tdplot_screen_coords] (-1,7.4) -- (1,7.4) coordinate[midway] (hang);
          %
          draw[dashed] plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw[dashed] (wpyr/2,wpyr/2,zpyr)
          -- (-wpyr/2,wpyr/2,zpyr) -- (-wpyr/2,-wpyr/2,zpyr)
          (-wpyr/2,wpyr/2,zpyr) -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved);
          draw[fill=gray!30,fill opacity=0.5]
          (-wpyr/2,-wpyr/2,zpyr) -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (wpyr/2,-wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!50,fill opacity=0.5] (wpyr/2,-wpyr/2,zpyr)
          -- (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (wpyr/2,wpyr/2,zpyr)
          -- cycle;
          draw[fill=gray!20,fill opacity=0.5]
          (wtop/2,-wtop/2,zpyr+hpyr-hremoved)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- cycle;
          pgfmathsetmacro{whpyr}{wpyr-(waterlevel-zpyr)*wpyr/hpyr} % width of pyramid at water level
          begin{scope}
          pgfmathtruncatemacro{itest}{sign(-(waterlevel-zpyr)+(hpyr-hremoved))}
          ifnumitest=1
          clip (-whpyr/2,-whpyr/2,waterlevel)
          -- (whpyr/2,-whpyr/2,waterlevel) -- (whpyr/2,whpyr/2,waterlevel)
          -- (wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,wtop/2,zpyr+hpyr-hremoved)
          -- (-wtop/2,-wtop/2,zpyr+hpyr-hremoved) -- (-whpyr/2,-whpyr/2,waterlevel)
          [reverseclip];
          fi
          fill[blue,opacity=0.2]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi+360] ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel);
          end{scope}
          fill[blue,opacity=0.4]
          plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},waterlevel)
          --
          plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi]
          ({rcyl*cos(t)},{rcyl*sin(t)},0);
          draw plot[smooth,variable=t,domain=tdplotmainphi:tdplotmainphi-180]
          ({rcyl*cos(t)},{rcyl*sin(t)},0)
          -- plot[smooth,variable=t,domain=tdplotmainphi-180:tdplotmainphi+180] ({rcyl*cos(t)},{rcyl*sin(t)},hcyl)
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},0) --
          ({rcyl*cos(tdplotmainphi)},{rcyl*sin(tdplotmainphi)},hcyl);
          draw (hang) -- (0,0,zpyr+hpyr-hremoved);
          % node[anchor=north west,tdplot_screen_coords,align=right]
          % at (1,7.75){waterlevel\ zpyr};
          end{tikzpicture}}
          end{document}


          enter image description here







          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Feb 6 at 15:22

























          answered Feb 4 at 6:22









          marmotmarmot

          118k6151284




          118k6151284













          • The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

            – Thumbolt
            Feb 4 at 6:28






          • 3





            Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

            – user31729
            Feb 4 at 9:28






          • 1





            @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

            – Servaes
            Feb 4 at 12:09






          • 2





            @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

            – marmot
            Feb 4 at 15:31






          • 1





            @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

            – Circumscribe
            Feb 6 at 15:31



















          • The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

            – Thumbolt
            Feb 4 at 6:28






          • 3





            Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

            – user31729
            Feb 4 at 9:28






          • 1





            @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

            – Servaes
            Feb 4 at 12:09






          • 2





            @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

            – marmot
            Feb 4 at 15:31






          • 1





            @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

            – Circumscribe
            Feb 6 at 15:31

















          The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

          – Thumbolt
          Feb 4 at 6:28





          The top of the pyramid should be removed so that the resulting cross-section is a square. The rope is attached to the center of that square.

          – Thumbolt
          Feb 4 at 6:28




          3




          3





          Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

          – user31729
          Feb 4 at 9:28





          Well, the pyramid is apparently full of holes -- the water level does not rise during the lowering of the pyramid. ;-)

          – user31729
          Feb 4 at 9:28




          1




          1





          @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

          – Servaes
          Feb 4 at 12:09





          @ChristianHupfer Perhaps the dotted line at the bottom suggests an infinitely long cilinder?

          – Servaes
          Feb 4 at 12:09




          2




          2





          @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

          – marmot
          Feb 4 at 15:31





          @ChristianHupfer That's a so-called well-tempered pyramid, which changes the water temperature in such a way that the water level remains constant. ;-)

          – marmot
          Feb 4 at 15:31




          1




          1





          @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

          – Circumscribe
          Feb 6 at 15:31





          @marmot: Yeah, that's probably wise, since it'd be hard to notice the difference. The change in water level looks more realistic now, but also less impressive somehow :).

          – Circumscribe
          Feb 6 at 15:31


















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