How can I change the color between the two circles?

Question

shreen elsapa 2024-11-8，17:28

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2165003-how-can-i-change-the-color-between-the-two-circles

评论： Voss 2024-11-8，21:11

采纳的回答： Voss

在 MATLAB Online 中打开

% Parameters for the inner and outer circles

radius_inner = 1; % Radius of the inner (solid sphere)

radius_outer = 1.5; % Radius of the outer (porous shell)

% Create a figure

figure;

hold on;

axis equal;

% Generate points for the circles

theta = linspace(0, 2*pi, 100);

% Coordinates for the inner circle

x_inner = radius_inner * cos(theta);

y_inner = radius_inner * sin(theta);

% Coordinates for the outer circle

x_outer = radius_outer * cos(theta);

y_outer = radius_outer * sin(theta);

% Plot the outer circle and fill the area between circles with a color

fill([x_outer, fliplr(x_inner)], [y_outer, fliplr(y_inner)], [0.9, 0.9, 0.9], 'EdgeColor', 'k', 'FaceAlpha', 0.5); % Light gray color for the porous shell

% Plot the inner circle with a different color

fill(x_inner, y_inner, [0.8, 0.8, 0.8], 'EdgeColor', 'k'); % Darker gray color for solid sphere

% Set axis limits and hide axes

axis([-2 2 -2 2]);

axis off;

hold off;

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Voss 2024-11-8，17:31

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2165003-how-can-i-change-the-color-between-the-two-circles#answer_1543058

编辑：Voss 2024-11-8，17:32

在 MATLAB Online 中打开

Change the third argument to the first fill() call. Example:

% Parameters for the inner and outer circles

radius_inner = 1; % Radius of the inner (solid sphere)

radius_outer = 1.5; % Radius of the outer (porous shell)

% Create a figure

figure;

hold on;

axis equal;

% Generate points for the circles

theta = linspace(0, 2*pi, 100);

% Coordinates for the inner circle

x_inner = radius_inner * cos(theta);

y_inner = radius_inner * sin(theta);

% Coordinates for the outer circle

x_outer = radius_outer * cos(theta);

y_outer = radius_outer * sin(theta);

% Plot the outer circle and fill the area between circles with a color

fill([x_outer, fliplr(x_inner)], [y_outer, fliplr(y_inner)], [0, 0.9, 0], 'EdgeColor', 'k', 'FaceAlpha', 0.5); % Green color for the porous shell

% Plot the inner circle with a different color

fill(x_inner, y_inner, [0.8, 0.8, 0.8], 'EdgeColor', 'k'); % Dark gray color for solid sphere

% Set axis limits and hide axes

axis([-2 2 -2 2]);

axis off;

hold off;

13 个评论
显示 11更早的评论隐藏 11更早的评论

shreen elsapa 2024-11-8，17:34

在 MATLAB Online 中打开

@Voss thanks

I need the following:

% Parameters for the solid sphere and porous shell

a = 1; % Radius of the solid sphere

b = 1.5; % Outer radius of the porous shell

% Create the figure

figure;

hold on;

axis equal;

% Plot the solid sphere

theta = linspace(0, 2*pi, 100);

x_solid = a * cos(theta);

y_solid = a * sin(theta);

fill(x_solid, y_solid, [0.8 0.8 0.8], 'EdgeColor', 'k'); % Gray color for solid sphere

% Plot the porous shell

x_shell = b * cos(theta);

y_shell = b * sin(theta);

fill(x_shell, y_shell, [0.9 0.9 0.9], 'EdgeColor', 'k', 'FaceAlpha', 0.5); % Lighter shade for porous shell

% Define plot boundaries and resolution for porous structure

x_limits = [-2, 2];

y_limits = [-2, 2];

n_pores = 1000; % Number of pores (random points)

% Generate random pore positions

rng(1); % For reproducibility

x_pores = x_limits(1) + (x_limits(2) - x_limits(1)) * rand(n_pores, 1);

y_pores = y_limits(1) + (y_limits(2) - y_limits(1)) * rand(n_pores, 1);

% Filter out pores that are inside the solid sphere and porous shell

dist_to_solid = sqrt(x_pores.^2 + y_pores.^2); % Distance from each pore to the center

pores_outside = (dist_to_solid > b); % Only include points outside the porous shell

% Plot the pores outside the porous shell

plot(x_pores(pores_outside), y_pores(pores_outside), 'b.', 'MarkerSize', 10);

% Labeling solid sphere and porous shell

text(0.3, -0.3, 'solid sphere', 'HorizontalAlignment', 'center', 'VerticalAlignment', 'middle', 'HorizontalAlignment', 'right', 'Interpreter','latex','FontSize',14,'FontName','TiemsNewRoman');

text(b,-2,-2, 'porous micropolar', 'HorizontalAlignment', 'right', 'Interpreter','latex','FontSize',14,'FontName','TiemsNewRoman');

% Set plot limits and hide axes

axis([-2 2 -2 2]);

axis off;

hold off;

Voss 2024-11-8，17:45

在 MATLAB Online 中打开

Rather than having the outer circle semi-transparent and on top the inner circle, make the outer circle underneath the inner circle by creating the outer circle first and remove its transparency (i.e., make it fully opaque).

Modify its color as desired by modifying the third input to fill().

% Parameters for the solid sphere and porous shell

a = 1; % Radius of the solid sphere

b = 1.5; % Outer radius of the porous shell

% Create the figure

figure;

hold on;

axis equal;

theta = linspace(0, 2*pi, 100);

% Plot the porous shell

x_shell = b * cos(theta);

y_shell = b * sin(theta);

fill(x_shell, y_shell, [0 0.9 0], 'EdgeColor', 'k'); % green color porous shell

% Plot the solid sphere

x_solid = a * cos(theta);

y_solid = a * sin(theta);

fill(x_solid, y_solid, [0.8 0.8 0.8], 'EdgeColor', 'k'); % Gray color for solid sphere

% Define plot boundaries and resolution for porous structure

x_limits = [-2, 2];

y_limits = [-2, 2];

n_pores = 1000; % Number of pores (random points)

% Generate random pore positions

rng(1); % For reproducibility

x_pores = x_limits(1) + (x_limits(2) - x_limits(1)) * rand(n_pores, 1);

y_pores = y_limits(1) + (y_limits(2) - y_limits(1)) * rand(n_pores, 1);

% Filter out pores that are inside the solid sphere and porous shell

dist_to_solid = sqrt(x_pores.^2 + y_pores.^2); % Distance from each pore to the center

pores_outside = (dist_to_solid > b); % Only include points outside the porous shell

% Plot the pores outside the porous shell

plot(x_pores(pores_outside), y_pores(pores_outside), 'b.', 'MarkerSize', 10);

% Labeling solid sphere and porous shell

text(0.3, -0.3, 'solid sphere', 'HorizontalAlignment', 'center', 'VerticalAlignment', 'middle', 'HorizontalAlignment', 'right', 'Interpreter','latex','FontSize',14,'FontName','TiemsNewRoman');

text(b,-2,-2, 'porous micropolar', 'HorizontalAlignment', 'right', 'Interpreter','latex','FontSize',14,'FontName','TiemsNewRoman');

% Set plot limits and hide axes

axis([-2 2 -2 2]);

axis off;

hold off;

shreen elsapa 2024-11-8，19:42

在 MATLAB Online 中打开

% Parameters for the solid sphere and porous shell

a = 2; % Radius of the solid sphere

b = 3; % Outer radius of the porous shell (increased space between annulus)

% Create the figure

figure;

hold on;

axis equal;

theta = linspace(0, 2*pi, 100);

% Plot the surrounding fluid (gray region) outside the porous shell

% Increase the fluid region to cover a larger area

%fill([-4 4 4 -4], [-4 -4 4 4], [0.5 0.5 0.5], 'EdgeColor', 'none'); % Increased gray fluid region

%fill([-4 4 4 -4], [-4 -4 4 4], [0 0 1], 'EdgeColor', 'none'); % Blue color

fill([-6 6 6 -6], [-6 -6 6 6], [1 1 1], 'EdgeColor', 'none'); % White color for the fluid region

% Plot the porous shell (within radius b)

x_shell = b * cos(theta);

y_shell = b * sin(theta);

fill(x_shell, y_shell, [1 1 1], 'EdgeColor', 'k'); % Green color for porous shell

% Plot the solid sphere (within radius a)

x_solid = a * cos(theta);

y_solid = a * sin(theta);

fill(x_solid, y_solid, [0.8 0.8 0.8], 'EdgeColor', 'k'); % Gray color for solid sphere

% Define plot boundaries and resolution for porous structure

x_limits = [-3, 3]; % Adjusted limits to accommodate expanded fluid region

y_limits = [-3, 3];

n_pores = 500; % Number of pores (random points)

% Generate random pore positions within the annular region (between a and b)

rng(1); % For reproducibility

radii = a + (b - a) * rand(n_pores, 1); % Random radii between a and b

angles = 2 * pi * rand(n_pores, 1); % Random angles between 0 and 2*pi

% Convert polar coordinates to Cartesian coordinates

x_pores = radii .* cos(angles);

y_pores = radii .* sin(angles);

% Plot the pores within the annulus

plot(x_pores, y_pores, 'b.', 'MarkerSize', 10);

% Labeling solid sphere and porous shell

text(a,3.5,2, 'Soft Sphere', 'HorizontalAlignment', 'center', 'VerticalAlignment', 'middle', 'FontSize', 14, 'FontName', 'Times New Roman');

text(b,-3.5,3, 'Micropolar Fluid', 'HorizontalAlignment', 'right', 'Interpreter', 'latex', 'FontSize', 14, 'FontName', 'Times New Roman');

% Set plot limits and hide axes

axis([-4 4 -4 4]); % Adjusted plot limits to accommodate the expanded fluid region

axis off;

hold off;

shreen elsapa 2024-11-8，20:25

编辑：Voss 2024-11-8，20:27

在 MATLAB Online 中打开

@Voss how?

and I need to plot it in 3d but remove the pores from the surface of inside sphere but I can not SEE

% Define the radii of the spheres (larger values)

r1 = 5; % Radius of the first (inner) sphere

r2 = 10; % Radius of the second (outer) sphere

% Create the sphere coordinates for the first sphere

[Xi1, Yi1, Zi1] = sphere(100); % 100 specifies the resolution for finer detail

% Scale the coordinates for the first sphere

Xi1 = r1 * Xi1;

Yi1 = r1 * Yi1;

Zi1 = r1 * Zi1;

% Create the sphere coordinates for the second sphere

[Xi2, Yi2, Zi2] = sphere(100); % 100 resolution

% Scale the coordinates for the second sphere

Xi2 = r2 * Xi2;

Yi2 = r2 * Yi2;

Zi2 = r2 * Zi2;

% Define plot boundaries and resolution for porous structure

x_limits = [-12, 12];

y_limits = [-12, 12];

n_pores = 2000; % Number of pores (random points), increased for more density

% Generate random points for the porous medium in the annular region

theta = 2*pi * rand(n_pores, 1); % Random azimuthal angles

phi = acos(2 * rand(n_pores, 1) - 1); % Random polar angles

% Generate random radius values strictly between r1 and r2 (no pores on r1 surface)

r = (r2 - r1) * rand(n_pores, 1) + r1; % Random radii in the annulus

% Remove points that are exactly on the surface of the inner sphere (r == r1)

r(abs(r - r1) < 1e-3) = r1 + 0.01; % Ensure no points are exactly on the surface of the inner sphere

% Regenerate random angles for remaining pores (no need to adjust since they are valid for the entire region)

theta = 2*pi * rand(length(r), 1);

phi = acos(2 * rand(length(r), 1) - 1);

% Convert spherical to Cartesian coordinates for the pores

x_pores = r .* sin(phi) .* cos(theta);

y_pores = r .* sin(phi) .* sin(theta);

z_pores = r .* cos(phi);

% Plot the two spheres and the porous medium

figure;

hold on;

% Plot the first sphere (inner sphere)

surf(Xi1, Yi1, Zi1, 'FaceAlpha', 0.5, 'EdgeColor', 'none');

% Plot the second sphere (outer sphere)

surf(Xi2, Yi2, Zi2, 'FaceAlpha', 0.3, 'EdgeColor', 'none');

% Plot the random points (pores) in the annular region with moderate pore size

scatter3(x_pores, y_pores, z_pores, 10, 'filled', 'MarkerFaceColor', [0.5, 0.5, 0.5]);

% Adjust the axes to ensure the spheres are displayed properly

axis equal;

xlabel('X');

ylabel('Y');

zlabel('Z');

title('Larger Concentric Spheres with Moderate Pores in the Annulus (No Pores on Inner Surface)');

grid on;

% Set the view to 3D

view(3); % This ensures the plot is in 3D view

% Add a light source to make the spheres appear more realistic

light;

lighting gouraud;

hold off;

shreen elsapa 2024-11-8，20:38

@Voss not removed from the surface of a

Voss 2024-11-8，21:11

When viewing a 3d object in 2d, some parts of it will obscure some other parts. In this case, that means some pores in the annulus will appear in front of the inner sphere. Right?

请先登录，再进行评论。

How can I change the color between the two circles?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

13 个评论
显示 11更早的评论隐藏 11更早的评论

更多回答（0 个）

另请参阅

标签

Community Treasure Hunt

How can I change the color between the two circles?

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

13 个评论 显示 11更早的评论隐藏 11更早的评论

更多回答（0 个）

另请参阅

标签

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

13 个评论
显示 11更早的评论隐藏 11更早的评论