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使用 Postscript 符号生成新颜色或更改线条颜色

tag-icon • tag-icon color pstricks postscript
使用 Postscript 符号生成新颜色或更改线条颜色

我想使用

\psset{linecolor = blue!\mapDFVtoColor}

而\mapDFVtoColor定义为

\def\mapDFVtoColor{20 40 add 3.5 div}

下面是一个较长但精简的示例

\documentclass[dvips]{standalone}
\usepackage{pstricks, pstricks-add}

\begin{document}
\begin{pspicture}[showgrid = true](-4.5, -4.5)(4.5, 5)
    \def\radius{4\space}
    \def\Adeg{68\space}
    \def\Bdeg{30\space}

    \def\xp{2\space}
    \def\yp{1\space}
    \def\zp{1\space}

    \def\DistanceFromViewer{%
    \radius \Bdeg cos \Adeg sin mul mul \xp mul %
    \radius \Adeg cos \Bdeg cos mul mul \yp mul add %
    \radius \Bdeg sin mul \zp mul add %
    \radius dup mul sub abs %
    \radius div\space}

    \def\MinDist{0\space}
    \def\MaxDist{\radius 2 mul\space}
    \def\MinColor{40\space}
    \def\MaxColor{100\space}

    \def\mapDFVtoColor{%
    \DistanceFromViewer \MinDist sub %
    \MaxColor \MinColor sub mul %
    \MaxDist \MinDist sub div %
    \MinColor add}

    \rput(1, 1){Distance: \psPrintValue{\DistanceFromViewer}}
    \rput(1, 0){Map: \psPrintValue{\mapDFVtoColor}}

    \psset{linecolor = blue!\mapDFVtoColor}

\end{pspicture}
\end{document}

我的想法是，我想根据与观察者的距离缩放 3D 中某个点的颜色。感谢您的评论。

答案1

以下是我对 egreg 评论的回答：

\documentclass[dvips]{standalone}
\usepackage{pstricks, pstricks-add}
\usepackage{fp}

\begin{document}
\begin{pspicture}[showgrid = true](-4.5, -4.5)(4.5, 5)
    \def\radius{4\space}
    \def\Adeg{68\space}
    \def\Bdeg{30\space}

    \def\xp{2\space}
    \def\yp{1\space}
    \def\zp{1\space}

    \def\DistanceFromViewer{%
    \radius \Bdeg cos \Adeg sin mul mul \xp mul %
    \radius \Adeg cos \Bdeg cos mul mul \yp mul add %
    \radius \Bdeg sin mul \zp mul add %
    \radius dup mul sub abs %
    \radius div\space}

    \FPeval{\resultDistanceFromViewer}{%
    abs(\radius * cos(\FPpi * \Bdeg / 180) * sin(\FPpi * \Adeg / 180) * \xp + %
    \radius * cos(\FPpi * \Adeg / 180) * cos(\FPpi * \Bdeg / 180) * \yp + %
    \radius * sin(\FPpi * \Bdeg / 180) * \zp - %
    \radius * \radius) / (\radius)}

    \def\MinDist{0\space}
    \def\MaxDist{\radius 2 mul\space}
    \def\MinColor{40\space}
    \def\MaxColor{100\space}

    \def\mapDFVtoColor{%
    \DistanceFromViewer \MinDist sub %
    \MaxColor \MinColor sub mul %
    \MaxDist \MinDist sub div %
    \MinColor add}

    \FPeval{\resulmapDFVtoColor}{%
    (\resultDistanceFromViewer - \MinDist) * %
    (\MaxColor - \MinColor) / (\MaxDist - \MinDist) + \MinColor}

    \rput(1, 1){Distance: \psPrintValue{\DistanceFromViewer}}
    \rput(1, 0){Map: \psPrintValue{\mapDFVtoColor}}
    \rput(1, -1){Distance: \resultDistanceFromViewer}
    \rput(1, -2){Map: \resulmapDFVtoColor}

\end{pspicture}
\end{document}

它还显示了您从 postscript 代码和数字运算中获得的结果之间的比较fp。调用\psset{linecolor = blue!\resulmapDFVtoColor}也适用于此。

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