39.8. "gl" — *Graphics Library* interface
*****************************************

Obsoleto desde a versão 2.6: The "gl" module has been removed in
Python 3.

This module provides access to the Silicon Graphics *Graphics
Library*. It is available only on Silicon Graphics machines.

Aviso: 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:

* All (short, long, unsigned) int values are represented by Python
  integers.

* All float and double values are represented by Python floating
  point numbers. In most cases, Python integers are also allowed.

* All arrays are represented by one-dimensional Python lists. In
  most cases, tuples are also allowed.

* All string and character arguments are represented by Python
  strings, for instance, "winopen('Hi There!')" and "rotate(900,
  'z')".

* 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

     lmdef(deftype, index, np, props)

  is translated to Python as

     lmdef(deftype, index, props)

* 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

     getmcolor(i, &red, &green, &blue)

  is translated to Python as

     red, green, blue = getmcolor(i)

The following functions are non-standard or have special argument
conventions:

gl.varray(argument)

   Equivalent to but faster than a number of "v3d()" calls. The
   *argument* is a list (or tuple) of points. Each point must be a
   tuple of coordinates "(x, y, z)" or "(x, 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 "z = 0.0" if necessary (as
   indicated in the man page), and for each point "v3d()" is called.

gl.nvarray()

   Equivalent to but faster than a number of "n3f" and "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 "(x, y,
   z)". Three coordinates must be given. Float and int values may be
   mixed. For each pair, "n3f()" is called for the normal, and then
   "v3f()" is called for the point.

gl.vnarray()

   Similar to  "nvarray()" but the pairs have the point first and the
   normal second.

gl.nurbssurface(s_k, t_k, ctl, s_ord, t_ord, type)

   Defines a nurbs surface. The dimensions of "ctl[][]" are computed
   as follows: "[len(s_k) - s_ord]", "[len(t_k) - t_ord]".

gl.nurbscurve(knots, ctlpoints, order, type)

   Defines a nurbs curve. The length of ctlpoints is "len(knots) -
   order".

gl.pwlcurve(points, type)

   Defines a piecewise-linear curve. *points* is a list of points.
   *type* must be "N_ST".

gl.pick(n)
gl.select(n)

   The only argument to these functions specifies the desired size of
   the pick or select buffer.

gl.endpick()
gl.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.

Here is a tiny but complete example GL program in Python:

   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()

Ver também:

  PyOpenGL: The Python OpenGL Binding
     An interface to OpenGL is also available; see information about
     the **PyOpenGL** project online at
     http://pyopengl.sourceforge.net/.  This may be a better option if
     support for SGI hardware from before about 1996 is not required.


39.9. "DEVICE" — Constants used with the "gl" module
****************************************************

Obsoleto desde a versão 2.6: The "DEVICE" module has been removed in
Python 3.

This modules defines the constants used by the Silicon Graphics
*Graphics Library* that C programmers find in the header file
"<gl/device.h>". Read the module source file for details.


39.10. "GL" — Constants used with the "gl" module
*************************************************

Obsoleto desde a versão 2.6: The "GL" module has been removed in
Python 3.

This module contains constants used by the Silicon Graphics *Graphics
Library* from the C header file "<gl/gl.h>". Read the module source
file for details.
