TikZ specifying barycentric coordinates using just lists of numbers












5














Here's what I currently have to type:



documentclass{standalone}

usepackage{tikz}

begin{document}
begin{tikzpicture}
coordinate (a) at (90:3cm);
coordinate (b) at (210:3cm);
coordinate (c) at (-30:3cm);

node [above] at (a) {$a$};
node [below left] at (b) {$b$};
node [below right] at (c) {$c$};

draw [thick,green, fill=green,opacity=0.5]
(barycentric cs:a=1,b=0,c=0) --
(barycentric cs:a=1,b=0,c=1) --
(barycentric cs:a=1,b=1,c=0) -- cycle;

draw [ultra thick] (a) -- (b) -- (c) --cycle;
end{tikzpicture}
end{document}


This is a little tedious. Since I'll want to draw lots of shapes using the same a,b,c-based barycentric coordinates. Is there a way to pass an option to scope for example that would allow me to have (1,0,1) evaluate as (barycentric cs:a=1,b=0,c=1)?










share|improve this question



























    5














    Here's what I currently have to type:



    documentclass{standalone}

    usepackage{tikz}

    begin{document}
    begin{tikzpicture}
    coordinate (a) at (90:3cm);
    coordinate (b) at (210:3cm);
    coordinate (c) at (-30:3cm);

    node [above] at (a) {$a$};
    node [below left] at (b) {$b$};
    node [below right] at (c) {$c$};

    draw [thick,green, fill=green,opacity=0.5]
    (barycentric cs:a=1,b=0,c=0) --
    (barycentric cs:a=1,b=0,c=1) --
    (barycentric cs:a=1,b=1,c=0) -- cycle;

    draw [ultra thick] (a) -- (b) -- (c) --cycle;
    end{tikzpicture}
    end{document}


    This is a little tedious. Since I'll want to draw lots of shapes using the same a,b,c-based barycentric coordinates. Is there a way to pass an option to scope for example that would allow me to have (1,0,1) evaluate as (barycentric cs:a=1,b=0,c=1)?










    share|improve this question

























      5












      5








      5







      Here's what I currently have to type:



      documentclass{standalone}

      usepackage{tikz}

      begin{document}
      begin{tikzpicture}
      coordinate (a) at (90:3cm);
      coordinate (b) at (210:3cm);
      coordinate (c) at (-30:3cm);

      node [above] at (a) {$a$};
      node [below left] at (b) {$b$};
      node [below right] at (c) {$c$};

      draw [thick,green, fill=green,opacity=0.5]
      (barycentric cs:a=1,b=0,c=0) --
      (barycentric cs:a=1,b=0,c=1) --
      (barycentric cs:a=1,b=1,c=0) -- cycle;

      draw [ultra thick] (a) -- (b) -- (c) --cycle;
      end{tikzpicture}
      end{document}


      This is a little tedious. Since I'll want to draw lots of shapes using the same a,b,c-based barycentric coordinates. Is there a way to pass an option to scope for example that would allow me to have (1,0,1) evaluate as (barycentric cs:a=1,b=0,c=1)?










      share|improve this question













      Here's what I currently have to type:



      documentclass{standalone}

      usepackage{tikz}

      begin{document}
      begin{tikzpicture}
      coordinate (a) at (90:3cm);
      coordinate (b) at (210:3cm);
      coordinate (c) at (-30:3cm);

      node [above] at (a) {$a$};
      node [below left] at (b) {$b$};
      node [below right] at (c) {$c$};

      draw [thick,green, fill=green,opacity=0.5]
      (barycentric cs:a=1,b=0,c=0) --
      (barycentric cs:a=1,b=0,c=1) --
      (barycentric cs:a=1,b=1,c=0) -- cycle;

      draw [ultra thick] (a) -- (b) -- (c) --cycle;
      end{tikzpicture}
      end{document}


      This is a little tedious. Since I'll want to draw lots of shapes using the same a,b,c-based barycentric coordinates. Is there a way to pass an option to scope for example that would allow me to have (1,0,1) evaluate as (barycentric cs:a=1,b=0,c=1)?







      tikz-pgf diagrams coordinates






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked yesterday









      Seamus

      45k35216332




      45k35216332






















          3 Answers
          3






          active

          oldest

          votes


















          4














          You can define



          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}


          and then use it as



            draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;


          or combine with another command with 9 parameters



          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }


          and use as



          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}


          enter image description here



          MWE



          documentclass{standalone}

          usepackage{tikz}
          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}
          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }
          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;

          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer

















          • 1




            +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
            – Kpym
            yesterday





















          4














          If it is ok for you to use normalized barycentric coordinates, ie (x,y,z) such that x+y+z=1, then you can simply set x=(a),y=(b),z=(c). So in place of (1,1,0) you should use (.5,.5,0).



          documentclass{standalone}
          usepackage{tikz}

          begin{document}
          begin{tikzpicture}
          path
          (90:3cm) coordinate (a) node[above] {$a$}
          (210:3cm) coordinate (b) node[below left] {$b$}
          (-30:3cm) coordinate (c) node[below right] {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          (barycentric cs:a=1,b=0,c=0) --
          (barycentric cs:a=1,b=0,c=1) --
          (barycentric cs:a=1,b=1,c=0) -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;

          % set x=(a),y=(b),z=(c) and use normalized barycentric coordinates
          draw[ultra thick, red, dashed, x=(a),y=(b),z=(c)]
          (1,0,0) -- (.5,0,.5) -- (.5,.5,0) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here






          share|improve this answer





















          • Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
            – Seamus
            yesterday






          • 1




            When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
            – Kpym
            yesterday










          • @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
            – marmot
            yesterday



















          4














          You can also use insert path to abbreviate the coordinates.



          documentclass{standalone}

          usepackage{tikz}

          begin{document}
          begin{tikzpicture}[bcs/.style args={#1|#2|#3}{insert path={--(barycentric
          cs:a=#1,b=#2,c=#3)}}]
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5] (a)
          [bcs={1|0|1},bcs={1|1|0}] -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here



          Another thing you could do is to locally change the TikZ parser. Then the whole path really boils down to



            begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}


          where bary={a}{b}{c} install the barycentric coordinate system in the scope (we don't want it everywhere) and you really just have to specify the three numbers.



          documentclass[tikz,border=3.14mm]{standalone}

          makeatletter % https://tex.stackexchange.com/a/365418/121799
          tikzset{bary/.code n args={3}{
          deftikz@parse@splitxyz##1##2##3,##4,{%
          def@next{tikz@scan@one@point##1(barycentric cs:#1=##2,#2=##3,#3=##4)}%
          }}}
          makeatother

          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};
          begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}
          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer























          • Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
            – Sigur
            yesterday










          • @Sigur This impression never fades away, regardless how long you read it. ;-)
            – marmot
            yesterday










          • I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
            – Kpym
            yesterday










          • @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
            – marmot
            yesterday











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          3 Answers
          3






          active

          oldest

          votes








          3 Answers
          3






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          4














          You can define



          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}


          and then use it as



            draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;


          or combine with another command with 9 parameters



          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }


          and use as



          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}


          enter image description here



          MWE



          documentclass{standalone}

          usepackage{tikz}
          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}
          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }
          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;

          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer

















          • 1




            +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
            – Kpym
            yesterday


















          4














          You can define



          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}


          and then use it as



            draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;


          or combine with another command with 9 parameters



          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }


          and use as



          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}


          enter image description here



          MWE



          documentclass{standalone}

          usepackage{tikz}
          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}
          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }
          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;

          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer

















          • 1




            +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
            – Kpym
            yesterday
















          4












          4








          4






          You can define



          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}


          and then use it as



            draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;


          or combine with another command with 9 parameters



          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }


          and use as



          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}


          enter image description here



          MWE



          documentclass{standalone}

          usepackage{tikz}
          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}
          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }
          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;

          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer












          You can define



          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}


          and then use it as



            draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;


          or combine with another command with 9 parameters



          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }


          and use as



          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}


          enter image description here



          MWE



          documentclass{standalone}

          usepackage{tikz}
          newcommand{foo}[3]{(barycentric cs:a=#1,b=#2,c=#3)}
          newcommand{faa}[9]{
          draw [thick,green, fill=green,opacity=0.5]
          foo{#1}{#2}{#3} --
          foo{#4}{#5}{#6} --
          foo{#7}{#8}{#9} -- cycle;
          }
          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          foo{1}{0}{0} --
          foo{1}{0}{1} --
          foo{1}{1}{0} -- cycle;

          faa{1}{0}{0}{1}{0}{1}{1}{1}{1}

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered yesterday









          Sigur

          24.1k355137




          24.1k355137








          • 1




            +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
            – Kpym
            yesterday
















          • 1




            +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
            – Kpym
            yesterday










          1




          1




          +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
          – Kpym
          yesterday






          +1. Suggestion : use def in place of newcommand to make more "friendly" interface. For example defbc(#1:#2:#3){(barycentric cs:a=#1,b=#2,c=#3)} can be used after as bc(1:0:0).
          – Kpym
          yesterday













          4














          If it is ok for you to use normalized barycentric coordinates, ie (x,y,z) such that x+y+z=1, then you can simply set x=(a),y=(b),z=(c). So in place of (1,1,0) you should use (.5,.5,0).



          documentclass{standalone}
          usepackage{tikz}

          begin{document}
          begin{tikzpicture}
          path
          (90:3cm) coordinate (a) node[above] {$a$}
          (210:3cm) coordinate (b) node[below left] {$b$}
          (-30:3cm) coordinate (c) node[below right] {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          (barycentric cs:a=1,b=0,c=0) --
          (barycentric cs:a=1,b=0,c=1) --
          (barycentric cs:a=1,b=1,c=0) -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;

          % set x=(a),y=(b),z=(c) and use normalized barycentric coordinates
          draw[ultra thick, red, dashed, x=(a),y=(b),z=(c)]
          (1,0,0) -- (.5,0,.5) -- (.5,.5,0) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here






          share|improve this answer





















          • Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
            – Seamus
            yesterday






          • 1




            When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
            – Kpym
            yesterday










          • @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
            – marmot
            yesterday
















          4














          If it is ok for you to use normalized barycentric coordinates, ie (x,y,z) such that x+y+z=1, then you can simply set x=(a),y=(b),z=(c). So in place of (1,1,0) you should use (.5,.5,0).



          documentclass{standalone}
          usepackage{tikz}

          begin{document}
          begin{tikzpicture}
          path
          (90:3cm) coordinate (a) node[above] {$a$}
          (210:3cm) coordinate (b) node[below left] {$b$}
          (-30:3cm) coordinate (c) node[below right] {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          (barycentric cs:a=1,b=0,c=0) --
          (barycentric cs:a=1,b=0,c=1) --
          (barycentric cs:a=1,b=1,c=0) -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;

          % set x=(a),y=(b),z=(c) and use normalized barycentric coordinates
          draw[ultra thick, red, dashed, x=(a),y=(b),z=(c)]
          (1,0,0) -- (.5,0,.5) -- (.5,.5,0) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here






          share|improve this answer





















          • Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
            – Seamus
            yesterday






          • 1




            When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
            – Kpym
            yesterday










          • @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
            – marmot
            yesterday














          4












          4








          4






          If it is ok for you to use normalized barycentric coordinates, ie (x,y,z) such that x+y+z=1, then you can simply set x=(a),y=(b),z=(c). So in place of (1,1,0) you should use (.5,.5,0).



          documentclass{standalone}
          usepackage{tikz}

          begin{document}
          begin{tikzpicture}
          path
          (90:3cm) coordinate (a) node[above] {$a$}
          (210:3cm) coordinate (b) node[below left] {$b$}
          (-30:3cm) coordinate (c) node[below right] {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          (barycentric cs:a=1,b=0,c=0) --
          (barycentric cs:a=1,b=0,c=1) --
          (barycentric cs:a=1,b=1,c=0) -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;

          % set x=(a),y=(b),z=(c) and use normalized barycentric coordinates
          draw[ultra thick, red, dashed, x=(a),y=(b),z=(c)]
          (1,0,0) -- (.5,0,.5) -- (.5,.5,0) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here






          share|improve this answer












          If it is ok for you to use normalized barycentric coordinates, ie (x,y,z) such that x+y+z=1, then you can simply set x=(a),y=(b),z=(c). So in place of (1,1,0) you should use (.5,.5,0).



          documentclass{standalone}
          usepackage{tikz}

          begin{document}
          begin{tikzpicture}
          path
          (90:3cm) coordinate (a) node[above] {$a$}
          (210:3cm) coordinate (b) node[below left] {$b$}
          (-30:3cm) coordinate (c) node[below right] {$c$};

          draw [thick,green, fill=green,opacity=0.5]
          (barycentric cs:a=1,b=0,c=0) --
          (barycentric cs:a=1,b=0,c=1) --
          (barycentric cs:a=1,b=1,c=0) -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;

          % set x=(a),y=(b),z=(c) and use normalized barycentric coordinates
          draw[ultra thick, red, dashed, x=(a),y=(b),z=(c)]
          (1,0,0) -- (.5,0,.5) -- (.5,.5,0) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered yesterday









          Kpym

          15.7k23985




          15.7k23985












          • Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
            – Seamus
            yesterday






          • 1




            When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
            – Kpym
            yesterday










          • @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
            – marmot
            yesterday


















          • Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
            – Seamus
            yesterday






          • 1




            When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
            – Kpym
            yesterday










          • @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
            – marmot
            yesterday
















          Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
          – Seamus
          yesterday




          Aha! I was wondering about this. So $x=(a)$ just sets the "x" coordinate in xyz coordinates to be the vector to (a)?
          – Seamus
          yesterday




          1




          1




          When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
          – Kpym
          yesterday




          When you set x=(a),y=(b),z=(c) than (x,y,z) is a point with coordinates x.a+y.b+z.c. That's all.
          – Kpym
          yesterday












          @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
          – marmot
          yesterday




          @Kpym I am not angry and would like to see your other, nice answer revived. The only thing I am advocating is to refer to earlier posts by others, if they are related, something that you usually do.
          – marmot
          yesterday











          4














          You can also use insert path to abbreviate the coordinates.



          documentclass{standalone}

          usepackage{tikz}

          begin{document}
          begin{tikzpicture}[bcs/.style args={#1|#2|#3}{insert path={--(barycentric
          cs:a=#1,b=#2,c=#3)}}]
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5] (a)
          [bcs={1|0|1},bcs={1|1|0}] -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here



          Another thing you could do is to locally change the TikZ parser. Then the whole path really boils down to



            begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}


          where bary={a}{b}{c} install the barycentric coordinate system in the scope (we don't want it everywhere) and you really just have to specify the three numbers.



          documentclass[tikz,border=3.14mm]{standalone}

          makeatletter % https://tex.stackexchange.com/a/365418/121799
          tikzset{bary/.code n args={3}{
          deftikz@parse@splitxyz##1##2##3,##4,{%
          def@next{tikz@scan@one@point##1(barycentric cs:#1=##2,#2=##3,#3=##4)}%
          }}}
          makeatother

          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};
          begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}
          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer























          • Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
            – Sigur
            yesterday










          • @Sigur This impression never fades away, regardless how long you read it. ;-)
            – marmot
            yesterday










          • I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
            – Kpym
            yesterday










          • @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
            – marmot
            yesterday
















          4














          You can also use insert path to abbreviate the coordinates.



          documentclass{standalone}

          usepackage{tikz}

          begin{document}
          begin{tikzpicture}[bcs/.style args={#1|#2|#3}{insert path={--(barycentric
          cs:a=#1,b=#2,c=#3)}}]
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5] (a)
          [bcs={1|0|1},bcs={1|1|0}] -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here



          Another thing you could do is to locally change the TikZ parser. Then the whole path really boils down to



            begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}


          where bary={a}{b}{c} install the barycentric coordinate system in the scope (we don't want it everywhere) and you really just have to specify the three numbers.



          documentclass[tikz,border=3.14mm]{standalone}

          makeatletter % https://tex.stackexchange.com/a/365418/121799
          tikzset{bary/.code n args={3}{
          deftikz@parse@splitxyz##1##2##3,##4,{%
          def@next{tikz@scan@one@point##1(barycentric cs:#1=##2,#2=##3,#3=##4)}%
          }}}
          makeatother

          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};
          begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}
          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer























          • Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
            – Sigur
            yesterday










          • @Sigur This impression never fades away, regardless how long you read it. ;-)
            – marmot
            yesterday










          • I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
            – Kpym
            yesterday










          • @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
            – marmot
            yesterday














          4












          4








          4






          You can also use insert path to abbreviate the coordinates.



          documentclass{standalone}

          usepackage{tikz}

          begin{document}
          begin{tikzpicture}[bcs/.style args={#1|#2|#3}{insert path={--(barycentric
          cs:a=#1,b=#2,c=#3)}}]
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5] (a)
          [bcs={1|0|1},bcs={1|1|0}] -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here



          Another thing you could do is to locally change the TikZ parser. Then the whole path really boils down to



            begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}


          where bary={a}{b}{c} install the barycentric coordinate system in the scope (we don't want it everywhere) and you really just have to specify the three numbers.



          documentclass[tikz,border=3.14mm]{standalone}

          makeatletter % https://tex.stackexchange.com/a/365418/121799
          tikzset{bary/.code n args={3}{
          deftikz@parse@splitxyz##1##2##3,##4,{%
          def@next{tikz@scan@one@point##1(barycentric cs:#1=##2,#2=##3,#3=##4)}%
          }}}
          makeatother

          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};
          begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}
          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}





          share|improve this answer














          You can also use insert path to abbreviate the coordinates.



          documentclass{standalone}

          usepackage{tikz}

          begin{document}
          begin{tikzpicture}[bcs/.style args={#1|#2|#3}{insert path={--(barycentric
          cs:a=#1,b=#2,c=#3)}}]
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};

          draw [thick,green, fill=green,opacity=0.5] (a)
          [bcs={1|0|1},bcs={1|1|0}] -- cycle;

          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}


          enter image description here



          Another thing you could do is to locally change the TikZ parser. Then the whole path really boils down to



            begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}


          where bary={a}{b}{c} install the barycentric coordinate system in the scope (we don't want it everywhere) and you really just have to specify the three numbers.



          documentclass[tikz,border=3.14mm]{standalone}

          makeatletter % https://tex.stackexchange.com/a/365418/121799
          tikzset{bary/.code n args={3}{
          deftikz@parse@splitxyz##1##2##3,##4,{%
          def@next{tikz@scan@one@point##1(barycentric cs:#1=##2,#2=##3,#3=##4)}%
          }}}
          makeatother

          begin{document}
          begin{tikzpicture}
          coordinate (a) at (90:3cm);
          coordinate (b) at (210:3cm);
          coordinate (c) at (-30:3cm);

          node [above] at (a) {$a$};
          node [below left] at (b) {$b$};
          node [below right] at (c) {$c$};
          begin{scope}[bary={a}{b}{c}]
          draw [thick,green, fill=green,opacity=0.5]
          (1,0,0) -- (1,0,1) -- (1,1,0) -- cycle;
          end{scope}
          draw [ultra thick] (a) -- (b) -- (c) --cycle;
          end{tikzpicture}
          end{document}






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited yesterday

























          answered yesterday









          marmot

          88.9k4102191




          88.9k4102191












          • Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
            – Sigur
            yesterday










          • @Sigur This impression never fades away, regardless how long you read it. ;-)
            – marmot
            yesterday










          • I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
            – Kpym
            yesterday










          • @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
            – marmot
            yesterday


















          • Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
            – Sigur
            yesterday










          • @Sigur This impression never fades away, regardless how long you read it. ;-)
            – marmot
            yesterday










          • I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
            – Kpym
            yesterday










          • @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
            – marmot
            yesterday
















          Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
          – Sigur
          yesterday




          Every time I read your answers on TikZ I say to myself I have to study the user guide. I'm afraid the amount of new tools there I never read about!!
          – Sigur
          yesterday












          @Sigur This impression never fades away, regardless how long you read it. ;-)
          – marmot
          yesterday




          @Sigur This impression never fades away, regardless how long you read it. ;-)
          – marmot
          yesterday












          I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
          – Kpym
          yesterday




          I was thinking about this too, but using insert path={(barycentric cs:a=#1,b=#2,c=#3)} do not work at the end of the path. For this reason you added -- in the insert path, I suppose. But now you can only draw straight lines :(
          – Kpym
          yesterday












          @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
          – marmot
          yesterday




          @Kpym Yes, that's true. This great answer comes with a sort of coordinate system parser, which one may adopt to this situation here. Anyway, I added yet another possibility that changes the TikZ parser locally.
          – marmot
          yesterday


















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