% function hArrow = arrowPlot(initPoints, finishPoints, color)
% draw N arrow(s) using #d surfaces, from coordinate(s) |initPoints| (3 column x N rows)
% to coordinate |finishPoints| (coordinates in cartesian).
% |color| is optional, it is a 3 element row (1 color for all arrows) or a 3 columns by
% N rows array where N is the number of arrows (and incidently the number of rows for
% initPoints and finishPoints).
% Note : color has implementation problems when colored surfaces are already presents.
% might mess up the colormap => might need to be desactivated!!
%
%
% Examples:
%
% sphere(20);
% hold on;
% axis equal;
% arrowPlot([0, 0, 1.2], [0+0.8, 0, 1.2], [1, 0, 0]);
% arrowPlot([0, 0, 1.2], [0, 0+0.8, 1.2], [0, 1, 0]);
% arrowPlot([0, 0, 1.2], [0, 0, 1.2+0.8], [0, 0, 1]);
% set(gca,'zlim', [-1, 2])
%
%
% Draw a kind of reference frame centered on position [0, 0, 1.2]
% above a colored sphere centered on [0,0,0] with radius 1,
% The 3 reference axis are along X, Y, Z of the figure, with length 0.8 and
% have each a different color.
%
% sphere(20);
% hold on;
% axis equal;
% arrowPlot([[0, 0, 1.2]; [0, 0, 1.2]; [0, 0, 1.2]], ...
% [[0+0.8, 0, 1.2];[0, 0+0.8, 1.2] ; [0, 0, 1.2+0.8]], ...
% [[1, 0, 0]; [0, 1, 0] ; [0, 0, 1] ]);
% set(gca,'zlim', [-1, 2])
%
% Does the same as previous example, but arrowPlots uses an array for the 3 vectors.
%
%
% TODO : allow for different input type, i.e. origin point & incidence, azimuth and
% length of the arrow from this point.
% Change aspect ratio for the arrow parts
%
% Author : Emmanuel P. Dinnat
%
% Date : 2005
%
function hArrow = arrowPlot(initPoints, finishPoints, varargin)
if length(varargin) == 1
colorPoints = varargin{1};
else
colorPoints = [0.1,0.1,0.1];
end
lineWidth = 0.01;
for iPoint = 1:size(initPoints, 1)
init = initPoints(iPoint,:);
finish = finishPoints(iPoint,:);
color = colorPoints(min([iPoint, size(colorPoints, 1)]),:);
%% make surface for the line of the arrow with a cylinder of height = 0.9 and width = lineWidth
[xc, yc, zc] = cylinder(lineWidth);
zc = zc*0.9;
%% make surface for the tip of the arrow
% make a cone with a base 300% larger than the line and a tip = 0
[xt, yt, zt] = cylinder(lineWidth*3 - [0:0.1:1]*lineWidth*3);
% decrease the tip height to be 10% of the total arrow height
zt = zt/10;
%% join both part, putting tip above line, to make arrow object
xa = [xc; xt];
ya = [yc; yt];
za = [zc; zt + 0.9];
%% rotate, resize and translate arrow
lengthArrow = norm(finish - init);
xa = xa*lengthArrow;
ya = ya*lengthArrow;
za = za*lengthArrow;
% bring the asked arrow coordinates to origin
finish_temp = finish - init;
% derive rotation angles
[phi_rot, th_rot, R] = cart2sph(finish_temp(1), finish_temp(2), finish_temp(3));
th_rot = pi/2 - th_rot;
% apply rotations to arrow
% rotation around Y-axis
[phiArrowZX, R] = cart2pol(za, xa);
phiArrowZX = phiArrowZX + th_rot;
[za2, xa2] = pol2cart(phiArrowZX, R);
ya2 = ya;
% rotation around Z-axis
[phiArrowXY, R] = cart2pol(xa2, ya2);
phiArrowXY = phiArrowXY + phi_rot;
[xa3, ya3] = pol2cart(phiArrowXY, R);
za3 = za2;
% apply translation to arrow
xa3 = xa3 + init(1);
ya3 = ya3 + init(2);
za3 = za3 + init(3);
%% plot arrow
hArrow = surf(xa3, ya3, za3);
set(hArrow, 'facecolor', color, 'edgecolor', 'none', ...
'diffuseStrength', 0.5, 'AmbientStrength',0.5, ...
'SpecularStrength', 1,...
'meshstyle', 'row')
hold on
% let's try to restore original colors to already existing colored surfaces !!
climval = get(gca, 'clim');
set(hArrow, 'Cdata', zeros(13,21)+climval(1));
end
