How to color triplot faces?

Question

Manar Al Asad 2020-8-26

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https://ww2.mathworks.cn/matlabcentral/answers/584900-how-to-color-triplot-faces

回答： Nicolas Hadjittoouli 2023-6-21

I have a 3D DTM in the form of triangulation (has faces and vertices) where the vertices coordinates are in cartesian coordinates (X,Y,Z). I would like to plot the DTM colored based on the radial position of each point.

In 3D this looks like the following, where r1 is a structure that has 2 fields: facets which a connectivity list, and vertices which is the point coordinates:

llr1(:,1),llr1(:,2),llr1(:,3)] = cart2sph(r1.vertices(:,1),...
    r1.vertices(:,2),r1.vertices(:,3));    % convert to spherical coordinates to get radial position
llr1(:,1) = rad2deg(llr1(:,1));        % convert to degrees
llr1(:,2) = rad2deg(llr1(:,2));        % convert to degrees
figure(1)
trisurf(r1.obj.facets,r1.obj.vertices(:,1),r1.obj.vertices(:,2),...
    r1.obj.vertices(:,3),llr1(:,3))

Now I would like to do the same thing in 2D simple cylindrical projection

figure(2);
triplot(r1.obj.facets,llr1(:,1),llr1(:,2))

gives me a line map with the right connectivity

but now I would like to color the faces in the 2d plot. Has anyone encountered this problem before and has a simple solution to it?

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Answer 1

Cris LaPierre 2020-8-27

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I believe a triplot is a line plot. You can color the lines and markers (vertices), but there are no faces to color.

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Answer 2

Nicolas Hadjittoouli 2023-6-21

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I managed to go around the problem by saving the points and connectivity list of triplot and I inserted an extra column of ones(m, 1) and use triangulation function to re-create the triangulation. Assuming that m is the length of your points.

For example:

h = triplot(X);

C = h.ConnectivityList;

P = h.Points;

P = [P ones(size(P,1), 1)]

TO = triangulation(C, P);

trisurf(TO);

And after that you can use trisurf as usual to insert face colors.