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########################################################################
##
## Copyright (C) 2007-2025 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## This file is part of Octave.
##
## Octave is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING. If not, see
## <https://www.gnu.org/licenses/>.
##
########################################################################
## -*- texinfo -*-
## @deftypefn {} {} view (@var{azimuth}, @var{elevation})
## @deftypefnx {} {} view ([@var{azimuth} @var{elevation}])
## @deftypefnx {} {} view ([@var{x} @var{y} @var{z}])
## @deftypefnx {} {} view (2)
## @deftypefnx {} {} view (3)
## @deftypefnx {} {} view (@var{hax}, @dots{})
## @deftypefnx {} {[@var{azimuth}, @var{elevation}] =} view ()
## Query or set the viewpoint for the current axes.
##
## The parameters @var{azimuth} and @var{elevation} can be given as two
## arguments or as 2-element vector. The viewpoint can also be specified with
## Cartesian coordinates @var{x}, @var{y}, and @var{z}.
##
## The call @code{view (2)} sets the viewpoint to
## @w{@var{azimuth} = 0}@ and @w{@var{elevation} = 90}, which is the default
## for 2-D graphs.
##
## The call @code{view (3)} sets the viewpoint to
## @w{@var{azimuth} = -37.5}@ and @w{@var{elevation} = 30}, which is the
## default for 3-D graphs.
##
## If the first argument @var{hax} is an axes handle, then operate on
## this axes rather than the current axes returned by @code{gca}.
##
## If no inputs are given, return the current @var{azimuth} and
## @var{elevation}.
## @end deftypefn
function [azimuth, elevation] = view (varargin)
[hax, varargin, nargin] = __plt_get_axis_arg__ ("view", varargin{:});
if (nargin > 2)
print_usage ();
endif
if (nargout > 0 && nargin > 0)
error ("view: cannot simultaneously get and set viewpoint");
endif
if (isempty (hax))
hax = gca ();
endif
if (nargin == 0)
vw = get (hax, "view");
az = vw(1);
el = vw(2);
elseif (numel (varargin) == 1)
x = varargin{1};
if (numel (x) == 2)
az = x(1);
el = x(2);
elseif (numel (x) == 3)
if (x(2) == 0)
## special case for negative 0
[az, el] = cart2sph (x(2), x(1), x(3));
if (x(1) == 0)
## Matlab Compatibility: Force +0 azimuth instead of +/-0 or
## +/-180deg azimuth for z-aligned vector.
az = 0;
endif
else
[az, el] = cart2sph (-x(2), x(1), x(3));
endif
az *= 180/pi;
el *= 180/pi;
elseif (x == 2)
az = 0;
el = 90;
elseif (x == 3)
az = -37.5;
el = 30;
else
print_usage ();
endif
elseif (numel (varargin) == 2)
az = varargin{1};
el = varargin{2};
endif
if (nargin > 0)
set (hax, "view", [az, el]);
else
if (nargout == 1)
azimuth = [az, el];
elseif (nargout == 2)
azimuth = az;
elevation = el;
endif
endif
endfunction
%!test
%! hf = figure ("visible", "off");
%! unwind_protect
%! plot3 ([0,1], [0,1], [0,1]);
%! [az, el] = view ();
%! assert ([az, el], [-37.5, 30], eps);
%! view (2);
%! [az, el] = view ();
%! assert ([az, el], [0, 90], eps);
%! view ([1 1 0]);
%! [az, el] = view ();
%! assert ([az, el], [135, 0], eps);
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
%!test
%! hf = figure ("visible", "off");
%! unwind_protect
%! line ();
%! [az, el] = view ();
%! assert ([az, el], [0, 90], eps);
%! view (3);
%! [az, el] = view ();
%! assert ([az, el], [-37.5, 30], eps);
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
%!test <*57800>
%! hf = figure ("visible", "off");
%! unwind_protect
%! plot3 ([0,1], [0,1], [0,1]);
%! view ([0, 0, 1]);
%! [az, el] = view ();
%! assert ([az, el], [0, 90], eps);
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
%!test <*65641>
%! hf = figure ("visible", "off");
%! unwind_protect
%! plot3 ([0,1], [0,1], [0,1]);
%! view ([1, 0, 0]);
%! [az, el] = view ();
%! assert ([az, el], [90, 0], eps);
%! view ([-1, 0, 0]);
%! [az, el] = view ();
%! assert ([az, el], [-90, 0], eps);
%! view ([0, 1, 0]);
%! [az, el] = view ();
%! assert ([az, el], [180, 0], eps);
%! view ([0, -1, 0]);
%! [az, el] = view ();
%! assert ([az, el], [0, 0], eps);
%! view ([0, 0, 1]);
%! [az, el] = view ();
%! assert ([az, el], [0, 90], eps);
%! view ([0, 0, -1]);
%! [az, el] = view ();
%! assert ([az, el], [0, -90], eps);
%! view ([1, 0.001, 0]);
%! [az, el] = view ();
%! assert ([az, el], [90 + 0.001*180/pi, 0], eps ("single"));
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
%!test <*65641> # Verify compatible z-vector viewpoint.
%! hf = figure ("visible", "off");
%! unwind_protect
%! ml_out = [0, 90, Inf] .* ones (8, 1);
%! ml_out(1:2:end-1, 2) = -90;
%! output = NaN (8, 3);
%! plot3 ([0,1], [0,1], [0,1]);
%! idx = 1;
%! for x1 = [-0, 0]
%! for x2 = [-0, 0]
%! for x3 = [-1, 1]
%! view ([x1, x2, x3]);
%! [az, el] = view ();
%! output(idx, :) = [az, el, 1/az];
%! idx++;
%! endfor
%! endfor
%! endfor
%! assert (isequaln (output, ml_out));
%! unwind_protect_cleanup
%! close (hf);
%! end_unwind_protect
## Test input validation
%!error <Invalid call> view (0, 0, 1)
%!error <cannot simultaneously get and set> [a, b] = view ([1, 1, 1])
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