# cpython-withatomic / Doc / libgl.tex

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 \section{Built-in Module \sectcode{gl}} \bimodindex{gl} This module provides access to the Silicon Graphics {\em Graphics Library}. It is available only on Silicon Graphics machines. \strong{Warning:} Some illegal calls to the GL library cause the Python interpreter to dump core. In particular, the use of most GL calls is unsafe before the first window is opened. The module is too large to document here in its entirety, but the following should help you to get started. The parameter conventions for the C functions are translated to Python as follows: \begin{itemize} \item All (short, long, unsigned) int values are represented by Python integers. \item All float and double values are represented by Python floating point numbers. In most cases, Python integers are also allowed. \item All arrays are represented by one-dimensional Python lists. In most cases, tuples are also allowed. \item \begin{sloppypar} All string and character arguments are represented by Python strings, for instance, \code{winopen('Hi There!')} and \code{rotate(900, 'z')}. \end{sloppypar} \item All (short, long, unsigned) integer arguments or return values that are only used to specify the length of an array argument are omitted. For example, the C call \bcode\begin{verbatim} lmdef(deftype, index, np, props) \end{verbatim}\ecode is translated to Python as \bcode\begin{verbatim} lmdef(deftype, index, props) \end{verbatim}\ecode \item Output arguments are omitted from the argument list; they are transmitted as function return values instead. If more than one value must be returned, the return value is a tuple. If the C function has both a regular return value (that is not omitted because of the previous rule) and an output argument, the return value comes first in the tuple. Examples: the C call \bcode\begin{verbatim} getmcolor(i, &red, &green, &blue) \end{verbatim}\ecode is translated to Python as \bcode\begin{verbatim} red, green, blue = getmcolor(i) \end{verbatim}\ecode \end{itemize} The following functions are non-standard or have special argument conventions: \renewcommand{\indexsubitem}{(in module gl)} \begin{funcdesc}{varray}{argument} %JHXXX the argument-argument added Equivalent to but faster than a number of \code{v3d()} calls. The \var{argument} is a list (or tuple) of points. Each point must be a tuple of coordinates \code{(\var{x}, \var{y}, \var{z})} or \code{(\var{x}, \var{y})}. The points may be 2- or 3-dimensional but must all have the same dimension. Float and int values may be mixed however. The points are always converted to 3D double precision points by assuming \code{\var{z} = 0.0} if necessary (as indicated in the man page), and for each point \code{v3d()} is called. \end{funcdesc} \begin{funcdesc}{nvarray}{} Equivalent to but faster than a number of \code{n3f} and \code{v3f} calls. The argument is an array (list or tuple) of pairs of normals and points. Each pair is a tuple of a point and a normal for that point. Each point or normal must be a tuple of coordinates \code{(\var{x}, \var{y}, \var{z})}. Three coordinates must be given. Float and int values may be mixed. For each pair, \code{n3f()} is called for the normal, and then \code{v3f()} is called for the point. \end{funcdesc} \begin{funcdesc}{vnarray}{} Similar to \code{nvarray()} but the pairs have the point first and the normal second. \end{funcdesc} \begin{funcdesc}{nurbssurface}{s_k\, t_k\, ctl\, s_ord\, t_ord\, type} % XXX s_k[], t_k[], ctl[][] %\itembreak Defines a nurbs surface. The dimensions of \code{\var{ctl}[][]} are computed as follows: \code{[len(\var{s_k}) - \var{s_ord}]}, \code{[len(\var{t_k}) - \var{t_ord}]}. \end{funcdesc} \begin{funcdesc}{nurbscurve}{knots\, ctlpoints\, order\, type} Defines a nurbs curve. The length of ctlpoints is \code{len(\var{knots}) - \var{order}}. \end{funcdesc} \begin{funcdesc}{pwlcurve}{points\, type} Defines a piecewise-linear curve. \var{points} is a list of points. \var{type} must be \code{N_ST}. \end{funcdesc} \begin{funcdesc}{pick}{n} \funcline{select}{n} The only argument to these functions specifies the desired size of the pick or select buffer. \end{funcdesc} \begin{funcdesc}{endpick}{} \funcline{endselect}{} These functions have no arguments. They return a list of integers representing the used part of the pick/select buffer. No method is provided to detect buffer overrun. \end{funcdesc} Here is a tiny but complete example GL program in Python: \bcode\begin{verbatim} import gl, GL, time def main(): gl.foreground() gl.prefposition(500, 900, 500, 900) w = gl.winopen('CrissCross') gl.ortho2(0.0, 400.0, 0.0, 400.0) gl.color(GL.WHITE) gl.clear() gl.color(GL.RED) gl.bgnline() gl.v2f(0.0, 0.0) gl.v2f(400.0, 400.0) gl.endline() gl.bgnline() gl.v2f(400.0, 0.0) gl.v2f(0.0, 400.0) gl.endline() time.sleep(5) main() \end{verbatim}\ecode \section{Standard Modules \sectcode{GL} and \sectcode{DEVICE}} \stmodindex{GL} \stmodindex{DEVICE} These modules define the constants used by the Silicon Graphics {\em Graphics Library} that C programmers find in the header files \file{} and \file{}. Read the module source files for details.