Code covered by the BSD License

# geom3d

### David Legland (view profile)

19 Jun 2009 (Updated )

Library to handle 3D geometric primitives: create, intersect, display, and make basic computations

### Editor's Notes:

This file was selected as MATLAB Central Pick of the Week

drawCircleArc3d(arc, varargin)
```function varargout = drawCircleArc3d(arc, varargin)
%DRAWCIRCLEARC3D Draw a 3D circle arc
%
%   drawCircleArc3d([XC YC ZC R THETA PHI PSI START EXTENT])
%   [XC YC ZC]  : coordinate of arc center
%   [THETA PHI] : orientation of arc normal, in degrees (theta: 0->180).
%   PSI         : roll of arc (rotation of circle origin)
%   START       : starting angle of arc, from arc origin, in degrees
%   EXTENT      : extent of circle arc, in degrees (can be negative)
%
%   Drawing options can be specified, as for the plot command.
%
%   angles3, circles3d, drawCircle3d, drawCircleArc
%
%
%   ---------
%   author : David Legland
%   INRA - TPV URPOI - BIA IMASTE
%   created the 21/02/2005
%

%   HISTORY
%   2007-06-27 change 3D angle convention
%   2010-03-08 use drawPolyline3d
%   2011-06-21 use angles in degrees

if iscell(arc)
h = [];
for i = 1:length(arc)
h = [h drawCircleArc3d(arc{i}, varargin{:})]; %#ok<AGROW>
end
if nargout > 0
varargout = {h};
end
return;
end

if size(arc, 1) > 1
h = [];
for i = 1:size(arc, 1)
h = [h drawCircleArc3d(arc(i,:), varargin{:})]; %#ok<AGROW>
end
if nargout > 0
varargout = {h};
end
return;
end

xc  = arc(:,1);
yc  = arc(:,2);
zc  = arc(:,3);
r   = arc(:,4);

% get angle of normal
theta   = arc(:,5);
phi     = arc(:,6);
psi     = arc(:,7);

% get starting angle and angle extent of arc
start   = arc(:,8);
extent  = arc(:,9);

% positions on circle arc
N       = 60;
t       = linspace(start, start+extent, N+1) * pi / 180;

% compute coordinate of points
x       = r*cos(t)';
y       = r*sin(t)';
z       = zeros(length(t), 1);
curve   = [x y z];

% compute transformation from local basis to world basis
trans   = localToGlobal3d(xc, yc, zc, theta, phi, psi);

% transform circle arc
curve   = transformPoint3d(curve, trans);

% draw the curve with specified options
h = drawPolyline3d(curve, varargin{:});

if nargout > 0
varargout = {h};
end

```