doc-en/par-datfile-en.tex

   1 \section{Using the data file types \texttt{.obj} and \texttt{.off}}
   2
   3 Sometimes it will helpful to use external files, either for reading or writing.
   4 When there is a solid which needs a long time to be calculated and which
   5 will be tested in different views or different colors, it is very
   6 interesting to save them externally and then only reread them by
   7 avoiding the time expensive recalculations. In particular, this technique
   8 is often used to generate some animations.
   9 One can also export a solid by that method to reuse with another software.
  10
  11 For \texttt{pst-solides3d}, all the procedures of reading$/$writing are
  12 delegated to the  PostScript interpreter (and not to \TeX {} or \LaTeX).
  13  Consequently it is not the \LaTeX{} compilation that will cause the
  14  execution of reading$/$writing, but the visualisation of the PostScript
  15  file that is produced.
  16
  17 Generally the reading of external files by a PostScript interpreter doesn't
  18 cause any trouble normally. The writing of files however, can cause some
  19 security problems and it is often the case that the PostScript viewer forbids
  20 the writing by default. So the system must be configured  to get authorisation for that writing.
  21
  22 \encadre{By default, under Windows and Linux, the security of files on the
  23 hard drive is activated and doesn't allow to write on the drive.
  24 To deactivate that security option, more or less temporarily, here the two
  25 corresponding procedures:
  26
  27 \begin{description}
  28
  29   \item[Linux:] The advice from Jean-Michel \textsc{Sarlat}: the simplest will
  30   be to use GhostScript directly, within the console. As there is no image to wait for:
  31
  32 \$$>$ gs  -dNOSAFER  monfichier.ps quit.ps
  33   \item[Windows:] Within the menue \texttt{Options}, the option
  34     \textsf{Security of files} must be turned to unchecked.
  35 \end{description}}
  36
  37
  38 \subsection{\texttt{\Index{.dat}} files (specific to \texttt{pst-solides3d})}
  39
  40 In \texttt{pst-solides3d}, the data structure used for a solid has 4 fields.
  41 It can be stored in a set of $4$
  42 \texttt{.dat} files.
  43
  44
  45 \subsubsection{Writing \texttt{.dat} files}
  46
  47 One uses the action \Lkeyword{writesolid} within \Lcs{psSolid}, and one
  48 uses the option \Lkeyword{file} to specify the name of the file.
  49
  50 For example, let's look at the code below:
  51 \begin{verbatim}
  52 \psSolid[object=tore,
  53    file=montore,
  54    action=writesolid]
  55 \end{verbatim}
  56
  57 The command chain
  58 \Cadre{LaTeX->dvips->GSview (Windows) or gv (Linux)}
  59 first compiles, then transforms into PostScript to finally get
  60 visualised.
  61
  62 That last operation creates 4 files:
  63 \begin{compactitem}
  64   \item \texttt{montore-sommets.dat  } $\rightarrow$ the list of the vertices;
  65   \item \texttt{montore-faces.dat    } $\rightarrow$ the list of the faces;
  66   \item \texttt{montore-couleurs.dat } $\rightarrow$ the colors of the faces;
  67   \item \texttt{montore-io.dat       } $\rightarrow$ the limits of the indices
  68   of the external and internal faces.
  69 \end{compactitem}
  70 \encadre{All these four files will automatically be saved within the same folder as the generating file.}
  71
  72 \subsubsection{Reading \texttt{.dat} files}
  73
  74 We use the object \Lkeyword{datfile} of \Lcs{psSolid}, with the argument
  75 \Lkeyword{file} to specify the name.
  76 Now the code
  77 \begin{verbatim}
  78 \psSolid[object=datfile, file=montore]
  79 \end{verbatim}
  80 will allow us to use the object---now saved in the \texttt{.dat} files generated---
  81 as described in the previous paragraph.
  82
  83 \subsection{\texttt{.obj} files}
  84
  85 We use only a simplified form of the \texttt{.obj} format. In particular, the
  86 files should not contain a character like
  87 \verb+#+ (the character for a comment in that format).
  88
  89 This format just uses a single file and permits within this file to specify
  90 the vertices and the faces.
  91
  92 \subsubsection{Writing \texttt{\Index{.obj}} files}
  93
  94 One uses the action \Lkeyword{writeobj} in \Lcs{psSolid}, and one uses
  95 the option \Lkeyword{file} to specify the name of the file.
  96
  97 For example, the code below:
  98 \begin{verbatim}
  99 \psSolid[object=tore,
 100    file=montore,
 101    action=writeobj]
 102 \end{verbatim}
 103 will produce a single file \texttt{montore.obj} (after compilation and
 104 visualisation of the \texttt{.ps} that was produced).
 105
 106 \subsubsection{Reading \texttt{.obj} files}
 107
 108 One uses the option \Lkeyword{objfile} of \Lcs{psSolid}, with the argument
 109 \Lkeyword{file} to specify the name of the file.
 110 Now the following code
 111 \begin{verbatim}
 112 \psSolid[object=objfile, file=montore]
 113 \end{verbatim}
 114 will allow to use the object---now saved in the \texttt{.obj} file generated---as
 115 described in the previous paragraph.
 116
 117 \begin{LTXexample}[width=6cm]
 118 \psset{viewpoint=20 15 10 rtp2xyz,Decran=20}
 119 \begin{pspicture}(-3,-4)(3,3)
 120 \psframe*[linecolor=cyan!50](-3,-4)(1,3)
 121 \psSolid[object=objfile,
 122          unit=20,RotX=60,
 123          file=./rocket]%
 124 \end{pspicture}
 125 \end{LTXexample}
 126
 127
 128
 129 \subsection{\texttt{.off} files}
 130
 131 We use only a simplified form of the \texttt{.off} format. In particular, these
 132 files only comprise \verb+v+ and \verb+f+ entries.
 133
 134 This format just uses a single file and permits within this file to specify the
 135 vertices and the faces.
 136
 137 \subsubsection{Writing \texttt{\Index{.off}} files}
 138
 139 We use the action \Lkeyword{writeobj} in \Lcs{psSolid}, and we use the option
 140  \Lkeyword{file} to specify the name of the file.
 141
 142 For example the code below:
 143 \begin{verbatim}
 144 \psSolid[object=tore,
 145    file=montore,
 146    action=writeoff]
 147 \end{verbatim}
 148 will produce the \texttt{montore.off} file (after compilation and
 149 visualisation of the \texttt{.ps} that was produced).
 150
 151 \subsubsection{Reading.off files}
 152
 153 We use the option \Lkeyword{offfile} of \Lcs{psSolid}, with the argument
 154 \Lkeyword{file} to specify the name of the file.
 155 Now the following code
 156 \begin{verbatim}
 157 \psSolid[object=offfile, file=montore]
 158 \end{verbatim}
 159 will allow to use the object---now saved in the \texttt{.off} file
 160 generated---like described in the previous paragraph.
 161
 162 \endinput