Fixing my code to get proper output.

Hello All,

Please note I need to construct Delaunays disc in matlab. I tried to do it in following way but its not working properly. Can someone help me in fixing this code? Any help will be greatly appreciated. You are free to take any value of n, it doesnt matter. :) :P

% Script for delaunay's disc
 
clc
close all
figure
axis equal off
hold on
n=50;            % Declaring the value of n 
 
% Calculation of concentric circles
x = linspace(0,n,1000);
y1 = sqrt(n^2-x.^2);              % Calculation of circle equation for the top circle
y2 = -y1;                         % Constructing the Bottom circle
fill([x 0],[y1 0],rand(1,3))      % Filling the top circle with red color
fill([x 0],[y2 0],rand(1,3))

for k=n:-1:1
    x=linspace(-k,k,1000);
    y1 = sqrt(k^2-x.^2);
    y2= -y1;   
  
    if(mod(k,2)==0)
        fill(x,y1,rand(1,3))
        fill(x,y2,rand(1,3))   
    else
        fill(x,y1,rand(1,3))
        fill(x,y2,rand(1,3))
end
end

title('Delaunays disc')

hold off
shg

Below is the output I am getting when I am running this code.

However, I am supposed to get below output:

Please help me out with this.

Answer 1

[BhaTTa]

Hey @Ashis Jana, please refer to the below code:

% Script for a custom "Delaunay-like" disc with quadrant coloring
 
clc           % Clear the command window
close all     % Close all open figures
figure        % Create a new figure
axis equal off % Set equal aspect ratio and turn off axes ticks/labels
hold on       % Hold the current plot so we can draw multiple shapes

n = 50;       % Declaring the value of n (outermost radius)

% Define a high number of points for smooth arcs
num_points_per_quad = 100; 

% Loop from the largest radius (n) down to 1
for k = n:-1:1
    % --- Define Angles for Each Quadrant ---
    theta_q1 = linspace(0, pi/2, num_points_per_quad);       % Q1: 0 to 90 degrees
    theta_q2 = linspace(pi/2, pi, num_points_per_quad);      % Q2: 90 to 180 degrees
    theta_q3 = linspace(pi, 3*pi/2, num_points_per_quad);    % Q3: 180 to 270 degrees
    theta_q4 = linspace(3*pi/2, 2*pi, num_points_per_quad);  % Q4: 270 to 360 degrees

    % --- Generate Coordinates for Each Quadrant's Arc ---
    x_q1_arc = k * cos(theta_q1);
    y_q1_arc = k * sin(theta_q1);

    x_q2_arc = k * cos(theta_q2);
    y_q2_arc = k * sin(theta_q2);

    x_q3_arc = k * cos(theta_q3);
    y_q3_arc = k * sin(theta_q3);

    x_q4_arc = k * cos(theta_q4);
    y_q4_arc = k * sin(theta_q4);
    
    % --- Fill Each Quadrant with a NEW Random Color ---
    % For each fill, we create a closed polygon by combining the arc points with the origin (0,0)
    
    % Quadrant 1 (Top-Right)
    fill([x_q1_arc, 0], [y_q1_arc, 0], rand(1,3)); % rand(1,3) generates a new random color for R, G, B

    % Quadrant 2 (Top-Left)
    fill([x_q2_arc, 0], [y_q2_arc, 0], rand(1,3));

    % Quadrant 3 (Bottom-Left)
    fill([x_q3_arc, 0], [y_q3_arc, 0], rand(1,3));

    % Quadrant 4 (Bottom-Right)
    fill([x_q4_arc, 0], [y_q4_arc, 0], rand(1,3));
end

title('Delaunays Disc (Quadrant-Colored)'); % Updated title for clarity

hold off      % Release the plot to prevent further additions
shg           % Show the figure (bring to front)

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