How to a creat a sweeping radius, like that of a radar.

For my university assignment I have to create a projectile simulator in the form of a radar, and I am struggling to create a radius that sweeps through the circle and was wondering if anyone could help, thanks very much.

Answer 1

[Wayne King]

It's easy enough to simulate that, but are you just interested in something for visual effect? In other words, not tied to any underlying computation.

theta=0:.01:2*pi;
y=exp(1i*theta);

        for j=1:length(theta)
            h=compass(real(y(j)),imag(y(j)));
            set(h,'linewidth',2);
            set(h,'color',[0 0 0])
            title('(cos(\theta),sin(\theta))','fontsize',18);
            pause(.01);
        end

Answer 2

[Alex]

Thanks for the quick reply, not exactly what I was hoping for, I was thinking more of just a visual effect, that serves no real purpose other than to make it look more interesting for the code:

clear %Clear Command Workspace

clc %Clear Command Window

x_data=[15.88,18.81,21.76,24.88,27.67]; %x data values

y_data=[5.55,10.61,14.30,17.35,19.26]; %y data values

p=polyfit(x_data,y_data,2) %Plot line of best fit

for i=13:52 %For the range given

    x(i)=i;

    y(i)=p(1)*x(i)^2+p(2)*x(i)+p(3);

end

figure(1)

clf %Clear Figure 1

plot(x_data,y_data,'r*') %Plots points

hold on

plot(x,y) %Plots points

axis([-60,60,-60,60]) %Set axis limits

set(gca,'color','black') %Set grid area colour to black

set(gcf,'color','black') %Set grid out area colour to black

set(gca,'xcolor','w') %Set x axits colur to white

set(gca,'ycolor','w') %Set y axis colour to white

grid on %Turns Gridlines on

%Plots radar isolines

plot(0,0,'go', 'MarkerSize', 110)

plot(0,0,'go', 'MarkerSize', 220)

plot(0,0,'go', 'MarkerSize', 330)

plot(0,0,'go', 'MarkerSize', 440)

plot(0,0,'go', 'MarkerSize', 550)

plot(0,0,'go', 'MarkerSize', 660)

plot(0,0,'go', 'MarkerSize', 770)

a=p(1) %Value for a

b=p(2) %Value for b

c=p(3) %Value for c

d = sqrt(b^2 - 4*a*c); %Quadratic formula discriminant

x(1) = ( -b + d )/(2*a) %Solution 1

x(2) = ( -b - d )/(2*a) %Solution 2

Thanks again

Answer 3

[Iain]

This is NOT the full answer, but it should get you started.

 a = plot([0 xmax],[0 0],'r-');
 hold on
 b = plot(x,y,'bx');
 c = plot(x1,y1,'cx');

 for i = 0:360
  set(a,'XData',[0, xmax],'YData',[0 ymax*sin(i*pi/180)])

% figure out how close the line is to passing a marker, and if its close enough
set(b,'Markersize',BIG)

% and if it's not...
set(c,'Markersize',small)
pause(0.1)
end