Colouring Tetramesh - Element wise
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ADSW121365
am 21 Okt. 2019
Kommentiert: ADSW121365
am 27 Jan. 2022
I'm working with tetrahedral finite elements. I can happily set up a mesh and work with said mesh. A really simple example code then gives the following with 72 elements:
clear,close all; clc; dbstop if error;
Nx = 4; Ny =3; Nz = 3; %No. Nodes Nx*Ny Ny = odd
%Variables to create Mesh:
a = 1; b = 1; c = 2;
X = linspace(0,a,Nx); Y = linspace(0,c,Ny); Z = linspace(0,a,Nz);
[X,Y,Z] = meshgrid(X,Y,Z); X = X(:); Y = Y(:); Z=Z(:);
%Meshing:
TRI = delaunay(X,Y,Z);
N = [X,Y,Z]; %Node Coordinates Vector
%figure; triplot(TRI,X,Y);
figure; tetramesh(TRI,[X(:),Y(:),Z(:)]), xlabel('x'),ylabel('y'),zlabel('z');
As a part of my model, each individual element is assumed to be homogoenous and as such has a material property associated with it which for the example here is given by:
NE = size(TRI,1); %Number of Elements
Elements = 1:NE;
Rho_e = zeros(NE,1);
Rho_e(Elements(sum(Y(TRI) <= b,2)==3)) = rho;
When I'm working with triangles in 2D. I can make use of trisurf and create a plot of the material properties:
Nx = 13; Ny =13; %No. Nodes
%Variables to create Mesh:
a = 1; b = 1; c = 2;
X = linspace(0,a,Nx); Y = linspace(0,c,Ny);
[X,Y] = meshgrid(X,Y); X = X(:); Y = Y(:);
TRI = delaunay(X,Y); %Simple Mesh
figure;
trisurf(TRI,X,Y,0*X,Rho_e,'edgecolor','k','facecolor','interp');
I'm currently trying then to create this plot for a 3D mesh of delauney tetrahedra as set up in the previous code. My current attempt looks like:
tetramesh(TRI,[X,Y,Z],Rho_e,'facecolor','interp');
view(2);
axis equal; colorbar; xlim([0,a]); ylim([0,c]); zlim([0,a]);
Which results in the following error message:
Warning: Error creating or updating Patch
Error in value of property FaceVertexCData
Number of colors must equal number of vertices
> In defaulterrorcallback (line 12)
In Oct8_3DFEM (line 56)
My guess is that I somehow need to manipulate my Rho vector from reprsenting individual elements to individual vertices. However for physical purposes it is important I find Rho_e first. The final image I'm searching for will essentially be a 3D projection of the 2D one attached above. Any thoughts, advice or other suggestions would be greatly appreciated
Akzeptierte Antwort
darova
am 21 Okt. 2019
Manipulate with faceVertexCData property if you want to assing some colors
get(p)
%%
FaceVertexCData = [ (72 by 1) double array]
%%
Vertices = [ (169 by 3) double array]
Example
p1 = tetramesh(TRI,[X,Y,Z]);
set(p1,'facevertexcdata',jet(numel(X)),'facecolor','interp');
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Alessandro Sicilia
am 27 Jan. 2022
Maybe you no longer working on this, but i have found a faster and simpler way to fulfill the problem.
While the 'tetramesh' function is very slow when you use a high number of elements, the 'patch' function is amazing: furthermore it fills any element shape, regardless its solid or plane nature, guaranteeing also the color interpolation.
It should work as follow:
patch('Faces',TRI,'Vertices',[X Y Z],'FaceVertexCData',Rho_e,'FaceColor','interp')
Anyway, you can refer to the 'patch' function HelpPage in the Matlab documentation.
Hoping to have been useful, have a good day
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