How to rotate?

Question

han han 2020-5-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/538091-how-to-rotate

编辑： han han 2020-5-30

采纳的回答： Image Analyst

在 MATLAB Online 中打开

I want to modify the following program like the following figure.

a=0.5; 
b=2; 
m = 1000;
x = zeros(m,1);
y = zeros(m,1);
theta = linspace(0,2*pi,m);
for k = 1:m
        x(k) = a * cos(theta(k));
        y(k) = b * sin(theta(k));
end
for a=0:0.5:1
    for xc = 1:-1:0
R  = [cos(a) -sin(a); ...
      sin(a)  cos(a)];
rCoords = R*[x' ; y'];   
xr = rCoords(1,:)';      
yr = rCoords(2,:)';  
yc = 1;
grid on;
axis equal;
    end
     hold on
 plot(xr+xc,yr+yc,'b');
end

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Ameer Hamza 2020-5-30

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Answer 1

Image Analyst 2020-5-30

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/538091-how-to-rotate#answer_443015

在 MATLAB Online 中打开

han han, I have not heard back from you so I assume you had trouble adapting my demos. So I did the thing 100% for you to give you exactly what you showed:

% Demo to rotate an ellipse about a center that also rotates around a circle.
% By ImageAnalyst
clc;    % Clear the command window.
clearvars;
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
fontSize = 14;
xCenter = 23.5;
yCenter = 0.5;
a = 2.0;
b = 0.5;
r = a;
% First get an ellipse centered at the origin of the proper size and shape.
hEllipse = imellipse(gca,[-a, -b, 2*a, 2*b]); % Second argument defines ellipse shape and position.
% Get (x,y) coordinates from the ellipse.
disp(hEllipse);
xy = hEllipse.getVertices();
% Clear original ellipse from axes.
axesHandlesToChildObjects = findobj(gca, 'Type', 'line');
if ~isempty(axesHandlesToChildObjects)
	delete(axesHandlesToChildObjects);
end
x = xy(:,1);
y = xy(:,2);
% plot(x, y, 'r-');
xy = [x y];
% Now rotate the ellipse through other angles and centers.
angles = 0 : 22.5 : 360 - 22.5;
for k = 1 : length(angles)
	theta = angles(k);
	rotationArray = [cosd(theta) sind(theta); -sind(theta) cosd(theta)];
	% Make a rotated ellipse about the origin.
	rotated_xy = xy * rotationArray;
	% Now shift its center.
	xCenter2 = xCenter + (r - 0.25) * cosd(theta);
	yCenter2 = yCenter + (r - 0.25) * sind(theta);
	x = rotated_xy(:,1) + xCenter2;
	y = rotated_xy(:,2) + yCenter2;
	% Now plot the rotated ellipse.
	plot(x, y, 'color', 'b', 'LineWidth', 2);
	if k == 1
		axis square;
		grid on;
		hold on;
	end
end
title('Demo Specially Made for han han', 'FontSize', 30);

If this does what you want, can you Accept this answer (since it seems no one else is going to offer a different working solution). Thanks in advance.