MATLAB: How to Draw an Ellipse Flower like this

ellipse

I need to draw 8 ellipses on the same grid and the angle of deviation between each of them must be pi/8. I have attached a flower with 18 leaves and I need to make one with 8 leaves. Each 'leave' is an ellipse.

Thanks in advance and greetings

Best Answer

My attached demo does exactly that. Just adapt it to change the angle increment and center point.

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MATLAB: How to obtain an angular segment with its vertex on the center from a circular image

See the third example in the FAQ http://matlab.wikia.com/wiki/FAQ#How_do_I_create_a_circle.3F

xCenter = 12;
yCenter = 10;
theta = 0 : 0.01 : 2*pi;
radius = 5;
x = radius * cos(theta) + xCenter;
y = radius * sin(theta) + yCenter;
plot(x, y);
axis square;
xlim([0 20]);
ylim([0 20]);
grid on;

Adjust the starting and ending theta to be what you need them to be, then pass x and y into poly2mask() to get a binary image which can then multiply by your image.

mask = poly2mask(x,y,size(rgbImage, 1), size(rgbImage, 2));
% Mask the image using bsxfun() function
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, class(rgbImage)));

MATLAB: How to clear this plot

You should probably make your code into a function instead of copy-pasting it. That would highlight that you didn't define angles_Panel_0 or angles and used xy1 where you probably meant xy.

It would also show you that you forgot to do

delete(hEllipse1)

So the ellipse is still there.

You can use the code below, although you should add documentation for that function, and you should expain what you code is doing with comments.

angles_Panel_0=0;
xUECenter=5;
yUECenter=5;
a = 3;
b = 3;
r = a;
LineSpec='b';
plot_ellipse(a,b,r,xUECenter,yUECenter,angles_Panel_0,LineSpec)
angles=0;
xNodeCenter=6;
yNodeCenter=6;
a = 3;
b = 0.5;
r =  a;
LineSpec='m';
hold on;
plot_ellipse(a,b,r,xNodeCenter,yNodeCenter,angles,LineSpec)
hold off;
function plot_ellipse(a,b,r,xNodeCenter,yNodeCenter,angles,LineSpec)
%write documentation here explaing inputs and usage
hEllipse = imellipse(gca,[-a, -b, 2*a, 2*b]);  %#ok<IMELLPS>
xy = hEllipse.getVertices();
delete(hEllipse)
x = xy(:,1);
y = xy(:,2);
xy = [x y];
for k = 1 : length(angles)
    theta = angles(k);
    rotationArray = [cosd(theta) sind(theta); -sind(theta) cosd(theta)];
    rotated_xy = xy * rotationArray;
    xCenter = xNodeCenter + (r - 0.25) * cosd(theta);
    yCenter = yNodeCenter + (r - 0.25) * sind(theta);
    x = rotated_xy(:,1) + xCenter;
    y = rotated_xy(:,2) + yCenter;
    plot(x, y, LineSpec);
    if k == 1
        grid on;
        hold on;
    end
end
end

Best Answer

Related Solutions

MATLAB: How to obtain an angular segment with its vertex on the center from a circular image

MATLAB: How to clear this plot

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