How can I display a line in 3D with a colour gradient?

Question

Louis 2024-5-10

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2117531-how-can-i-display-a-line-in-3d-with-a-colour-gradient

回答： Voss 2024-5-10

Let’s say I have a set of 10 tridimensional points, represented as a 3 by 10 matrix, such as these points generated just for the sake of illustration:

n = 10;
x = linspace(1, 2, n);
y = cos(x);
z = y.^2;
points = [x' y' z']
points = 10x3
    1.0000    0.5403    0.2919
    1.1111    0.4437    0.1968
    1.2222    0.3416    0.1167
    1.3333    0.2352    0.0553
    1.4444    0.1260    0.0159
    1.5556    0.0152    0.0002
    1.6667   -0.0957    0.0092
    1.7778   -0.2055    0.0422
    1.8889   -0.3128    0.0978
    2.0000   -0.4161    0.1732
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I can display them as a line in 3D:

plot3(points(:,1,:), points(:,2,:), points(:,3,:));

My question is: how can I apply a color gradient to this line, so we can see in what direction does the line evolve (relative to the order of the point in the points matrix)?

I tried several methods, without success so far:

Calling plot3 with the c parameter (as suggested by an answer on the Internet): the c keyword is not recognised.
Calling colormap with a custom made map: no graph is displayed at all, even though no error is thrown.

cmap = [linspace(0, 1, n)' zeros(n, 1) zeros(n, 1)];

colormap(cmap);

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Answer 1

Voss 2024-5-10

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2117531-how-can-i-display-a-line-in-3d-with-a-colour-gradient#answer_1455801

在 MATLAB Online 中打开

n = 10;

x = linspace(1, 2, n);

y = cos(x);

z = y.^2;

points = [x' y' z']

points = 10x3

1.0000 0.5403 0.2919 1.1111 0.4437 0.1968 1.2222 0.3416 0.1167 1.3333 0.2352 0.0553 1.4444 0.1260 0.0159 1.5556 0.0152 0.0002 1.6667 -0.0957 0.0092 1.7778 -0.2055 0.0422 1.8889 -0.3128 0.0978 2.0000 -0.4161 0.1732

surf(points(:,[1 1]),points(:,[2 2]),points(:,[3 3]),[1:n; 1:n].', ...

'FaceColor','none','EdgeColor','interp','LineWidth',2)