How to assign gradual color to a 3d line based on values of another vector

Question

Martha 2015년 11월 13일

0
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https://kr.mathworks.com/matlabcentral/answers/254696-how-to-assign-gradual-color-to-a-3d-line-based-on-values-of-another-vector

댓글: Haoxin Zhou 2020년 7월 17일

Hi all, I want to assign colour to lines plotted between 3dpoints, based on the values of a fourth vector. The values of the fourth vector are not sorted in any way, and they are both positive and negative values. I did a for loop to plot a line between the nodes that have connectivity, and I'm assigning the color as well. I think I'm having problems with the way I'm sorting the fourth value. But can't figure it out how to make it work. Here is the code:

myColourMap=jet(m);
s=stresses;
[s,I]=sort(s);
for i=1:m
Intensity = I(i);
LineColour=myColourMap(Intensity,:);
plot3([ x(t1(i)) x(t2(i))], [ y(t1(i)) y(t2(i))], [ z(t1(i)) z(t2(i))],'Color', LineColour)
  hold on
end
axis equal
colorbar

The four vector is the 's' vector, and when I plotted the network of lines, the colour it assign to each one, does not represent the ascending or descending of the values in vector s(which represent stresses). I appreciate very much any help of how to plot the lines based on the values of a vector, or if the problem is the sorting, then, how to obtain the ordering indices of the vector s.

Thanks a lot in advance

Martha

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Answer 1

Mike Garrity 2015년 11월 13일

7
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https://kr.mathworks.com/matlabcentral/answers/254696-how-to-assign-gradual-color-to-a-3d-line-based-on-values-of-another-vector#answer_199734

MATLAB Online에서 열기

Unfortunately the line object that plot and plot3 create can't do color data interpolation. Several of the other objects can. The one that is most commonly used for this is patch. Probably because patch can do just about anything.

There's one thing to look out for when using patch for this. By default, it makes a closed loop like this:

 t = linspace(0,2*pi,100);
 x = cos(t);
 y = sin(t);
 z = t;
 c = cos(t).^2;
 colormap(hsv)
 patch(x,y,z,c,'FaceColor','none','EdgeColor','interp')
 colorbar
 view(3)

You need to add a nan to tell it not to do that.

t = linspace(0,2*pi,100);
x = cos(t);
y = sin(t);
z = t;
c = cos(t).^2;
colormap(hsv)
patch([x nan],[y nan],[z nan],[c nan],'FaceColor','none','EdgeColor','interp')
colorbar
view(3)