How to obtain union of three shapes given the coordinates
5 views (last 30 days)
Show older comments
Oluwaseyi Ogun
on 13 Dec 2021
Commented: Oluwaseyi Ogun
on 13 Dec 2021
I am trying to obtain the union of shapes comprising of 2 rectangles and a circle. Please does anyone know how to get the union coordinates? .Below is the matlab code, and the corresponding figure.
cy_l=0.3; length of rectangle outside the circle
r=0.5; % radius of circle
a=0.3; % width of rectangle
b=2*r+2*cy_l; % length of rectangle
centre=[0.5 0.3]; %circle centre
theta=0:2*pi/360:2*pi;
circ=[r*cos(theta')+centre(1) r*sin(theta')+centre(2)]; % circle coordinates
%% rectangle
xy=[centre(1)-(r+cy_l), centre(2)+a/2]; % top left coordinates of rectangle1
xy1=[centre(1)-a/2, centre(2)+(r+cy_l)]; %top left coordinate of rectangle2
R1=[xy(1), xy(1), xy(1)+b, xy(1)+b, xy(1);
xy(2)-a, xy(2), xy(2), xy(2)-a, xy(2)-a]; % coordinates of rectangle 1
R2= [ xy1(1), xy1(1), xy1(1)+a, xy1(1)+a, xy1(1);
xy1(2)-b, xy1(2), xy1(2), xy1(2)-b, xy1(2)-b]; %coordinates of rectangle 2
plot(circ(:,1), circ(:,2), 'k', R1(1,:), R1(2,:),'k', R2(1,:), R2(2,:), 'k', 'LineWidth', 2)
grid on
axis equal
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/832770/image.png)
0 Comments
Accepted Answer
Steven Lord
on 13 Dec 2021
I'd use polyshape.
cy_l=0.3; % length of rectangle outside the circle
r=0.5; % radius of circle
a=0.3; % width of rectangle
b=2*r+2*cy_l; % length of rectangle
centre=[0.5 0.3]; %circle centre
theta=0:2*pi/360:2*pi;
circ=polyshape(r*cos(theta')+centre(1), r*sin(theta')+centre(2)); % Circle
%% rectangle
xy=[centre(1)-(r+cy_l), centre(2)+a/2]; % top left coordinates of rectangle1
xy1=[centre(1)-a/2, centre(2)+(r+cy_l)]; %top left coordinate of rectangle2
R1=polyshape([xy(1), xy(1), xy(1)+b, xy(1)+b, xy(1)], ...
[xy(2)-a, xy(2), xy(2), xy(2)-a, xy(2)-a]); % rectangle 1
R2= polyshape([xy1(1), xy1(1), xy1(1)+a, xy1(1)+a, xy1(1)], ...
[xy1(2)-b, xy1(2), xy1(2), xy1(2)-b, xy1(2)-b]); % rectangle 2
plot([circ, R1, R2])
axis equal
% Show the union in a separate figure for comparison
figure
plot(union([circ, R1, R2]), 'FaceColor', 'g')
axis equal
More Answers (2)
Alex Alex
on 13 Dec 2021
Edited: Alex Alex
on 13 Dec 2021
may be command "polyxpoly" help you
[xi1,yi1] = polyxpoly(circ(:,1), circ(:,2), R1(1,:), R1(2,:))
[xi2,yi2] = polyxpoly(circ(:,1), circ(:,2), R2(1,:), R2(2,:))
[xi3,yi3] = polyxpoly(R1(1,:), R1(2,:), R2(1,:), R2(2,:))
plot(xi1,yi1, 'o')
plot(xi2,yi2, 'o')
plot(xi3,yi3, 'o')
John D'Errico
on 13 Dec 2021
Tivial.
- generate the three objects as polyshapes.
- Compute the union.
For example...
cy_l=0.3; % length of rectangle outside the circle
r=0.5; % radius of circle
a=0.3; % width of rectangle
b=2*r+2*cy_l; % length of rectangle
centre=[0.5 0.3]; %circle centre
theta=0:2*pi/360:2*pi;
circ=[r*cos(theta')+centre(1) r*sin(theta')+centre(2)]; % circle coordinates
%% rectangle
xy=[centre(1)-(r+cy_l), centre(2)+a/2]; % top left coordinates of rectangle1
xy1=[centre(1)-a/2, centre(2)+(r+cy_l)]; %top left coordinate of rectangle2
R1=[xy(1), xy(1), xy(1)+b, xy(1)+b, xy(1);
xy(2)-a, xy(2), xy(2), xy(2)-a, xy(2)-a]; % coordinates of rectangle 1
R2= [ xy1(1), xy1(1), xy1(1)+a, xy1(1)+a, xy1(1);
xy1(2)-b, xy1(2), xy1(2), xy1(2)-b, xy1(2)-b]; %coordinates of rectangle 2
PSc = polyshape(circ(:,1),circ(:,2));
PSr1 = polyshape(R1(1,:),R1(2,:));
PSr2 = polyshape(R2(1,:),R2(2,:));
PSu = union(union(PSc,PSr1),PSr2);
plot(PSu)
0 Comments
See Also
Categories
Find more on Elementary Polygons in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!