Pgfplots: enlargelimits = false no comportamento inconsistente do addplot3

Question

Tento plotar algumas coisas em 3D. Eu uso enlargelimits=falsekey na pgfplotssetdefinição e restrinjo a domain-1:1.

Ao traçar a primeira função, tudo funciona bem. O eixo atinge exatamente de -1 a 1:

Porém, quando uso o mesmo estilo para outra foto, parece que enlargelimits=falsenão tem efeito:

Alguém pode explicar por que isso acontece e o que posso fazer para evitar esse comportamento?

---

MWE

\documentclass{standalone}

\usepackage{pgfplots}

\pgfplotsset{%
  shapefunctionaxis/.style={%
    domain=-1.0:1.0,
    domain y=-1.0:1.0,
    enlargelimits=false,
    axis equal,
    xlabel=$\xi$,
    ylabel=$\eta$,
    zlabel=$N_{\i}$,
    zlabel style={rotate=-90},
    xtick distance={1.0},
    ytick distance={1.0},
    ztick distance={1.0},
    view={25}{30},% default is {25}{30}, pgfplots manual section 4.11.1
  }%
}

\begin{document}

% This works as expected:
\def\i{5}
\def\xii{0}
\def\etai{1.0}
% This does not work as expected:
%\def\i{4}
%\def\xii{-1.0}
%\def\etai{1.0}
\begin{tikzpicture}
  \begin{axis}[
    width=10cm,
    shapefunctionaxis,
  ]
    % Corner nodes
    \ifnum\ifnum\i=1 1\else\ifnum\i=2 1\else\ifnum\i=3 1\else\ifnum\i=4 1\else0\fi\fi\fi\fi%
      =1 %
      \addplot3[surf]{0.25*(1.0+\xii*x)*(1.0+\etai*y)*(\xii*x+\etai*y-1)};
    \else\fi
    % xi-edge middle nodes
    \ifnum\ifnum\i=5 1\else\ifnum\i=7 1\else0\fi\fi%
      =1 %
      \addplot3[surf]{0.5*(1.0-x*x)*(1.0+\etai*y)};
    \else\fi
    % eta-edge middle nodes
    \ifnum\ifnum\i=6 1\else\ifnum\i=8 1\else0\fi\fi%
      =1 %
      \addplot3[surf]{0.5*(1.0+\xii*x)*(1.0-y*y)};
    \else\fi
  \end{axis}
\end{tikzpicture}

\end{document}

Answer 1

De acordo com o manual

/pgfplots/axis equal={⟨true,false⟩}(inicialmente false)
Cada vetor unitário é definido com o mesmo comprimento enquanto as dimensões do eixo permanecem constantes. Depois, as proporções de tamanho para cada unidade em x e y serão as mesmas.
Os limites do eixo serão ampliados para compensar o efeito de escala.

---

Editado por krtek

A opção unit rescale keep size=truefoi exatamente a dica certa. Obrigado.

\documentclass{standalone}

\usepackage{pgfplots}

\pgfplotsset{%
  shapefunctionaxis/.style={%
    domain=-1.0:1.0,
    domain y=-1.0:1.0,
    enlargelimits=false,
    %axis equal,
    unit rescale keep size=true,
    xlabel=$\xi$,
    ylabel=$\eta$,
    zlabel=$N_{\i}$,
    zlabel style={rotate=-90},
    xtick distance={1.0},
    ytick distance={1.0},
    ztick distance={1.0},
    view={25}{30},% default is {25}{30}, pgfplots manual section 4.11.1
  }%
}

\begin{document}

% This works as expected:
%\def\i{5}
%\def\xii{0}
%\def\etai{1.0}
% These does not work as expected:
\def\i{4}
\def\xii{-1.0}
\def\etai{1.0}
\begin{tikzpicture}
  \begin{axis}[
    width=10cm,
    shapefunctionaxis,
  ]
    % Corner nodes
    \ifnum\ifnum\i=1 1\else\ifnum\i=2 1\else\ifnum\i=3 1\else\ifnum\i=4 1\else0\fi\fi\fi\fi%
      =1 %
      \addplot3[surf]{0.25*(1.0+\xii*x)*(1.0+\etai*y)*(\xii*x+\etai*y-1)};
    \else\fi
    % xi-edge middle nodes
    \ifnum\ifnum\i=5 1\else\ifnum\i=7 1\else0\fi\fi%
      =1 %
      \addplot3[surf]{0.5*(1.0-x*x)*(1.0+\etai*y)};
    \else\fi
    % eta-edge middle nodes
    \ifnum\ifnum\i=6 1\else\ifnum\i=8 1\else0\fi\fi%
      =1 %
      \addplot3[surf]{0.5*(1.0+\xii*x)*(1.0-y*y)};
    \else\fi
  \end{axis}
\end{tikzpicture}

\end{document}