# use patch to plot hexahedron with 20 nodes

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alize beemiel on 13 Nov 2020
Commented: alize beemiel on 13 Nov 2020
hi
i have a hexaedron with 20 nodes
i have coordonates X Y Z
and the conectivity [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20];
and the stress value of all nodes TZ
TZ=[ -0.0225
-0.0226
-0.0233
-0.0185
-0.0188
-0.0144
-0.0144
-0.0141
-0.0062
-0.0064
0
0
0
-0.0209
-0.0216
-0.0126
-0.0123
0
0
-0.0137]
how can i use patch to plot my hexaedon and take all nodes to make interpolation for facecolor ith TZ
i use this
patch('Faces',Rectangles,'Vertices',[Vertice(:,1) Vertice(:,2) Vertice(:,3)],'FaceVertexCData',TZ,'FaceColor','interp','Marker','.');
vertice is X Y Z for the hexaedron
TZ is color face
but when i come to determine rectangle or the point to make faces i have problem
i wante to use all points of hexaedre
i do this but it deasnt work
Bricks =[1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20];
Rectangles=[];
Rectangles=[Rectangles ; [Bricks(:,1) Bricks(:,2) Bricks(:,3) Bricks(:,4) Bricks(:,5) Bricks(:,6) Bricks(:,7) Bricks(:,8)]];
Rectangles=[Rectangles ; [Bricks(:,13) Bricks(:,14) Bricks(:,15) Bricks(:,16) Bricks(:,17) Bricks(:,18) Bricks(:,19) Bricks(:,20)]];
Rectangles=[Rectangles ; [Bricks(:,1) Bricks(:,2) Bricks(:,3) Bricks(:,10) Bricks(:,15) Bricks(:,14) Bricks(:,13) Bricks(:,9)]];
Rectangles=[Rectangles ; [Bricks(:,3) Bricks(:,4) Bricks(:,5) Bricks(:,11) Bricks(:,17) Bricks(:,16) Bricks(:,15) Bricks(:,10)]];
Rectangles=[Rectangles ; [Bricks(:,5) Bricks(:,6) Bricks(:,7) Bricks(:,12) Bricks(:,19) Bricks(:,18) Bricks(:,17) Bricks(:,11)]];
Rectangles=[Rectangles ; [Bricks(:,7) Bricks(:,8) Bricks(:,1) Bricks(:,9) Bricks(:,13) Bricks(:,20) Bricks(:,19) Bricks(:,12)]];
some one tell me use rectangle and take just the point of a corner but it give me a wrong resultat
thank you for any help
##### 2 CommentsShowHide 1 older comment
alize beemiel on 13 Nov 2020
ok

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### Accepted Answer

Bruno Luong on 13 Nov 2020
Edited: Bruno Luong on 13 Nov 2020
Here we go
[x,y,z]=ndgrid(0:2);
xyz = [x(:) y(:) z(:)];
xyz(sum(xyz==1,2)>1,:)=[];
x=xyz(:,1);y=xyz(:,2);z=xyz(:,3);
a=atan2(z-1.001,x-1);
[~,is]=sortrows([y -a]);
xyz=xyz(is,:);
F = zeros(6,8);
i = 0;
for c=1:3
for v=[0 2]
r = find(xyz(:,c)==v);
st = xyz(r,:);
st(:,c) = [];
st = (st-[1 1]);
a = sign(v-1)*atan2(st(:,2),st(:,1));
[~,is] = sort(a);
i = i+1;
F(i,:) = r(is);
end
end
xyz = xyz/2;
% Create a dummy Stress
%Stress = 2-sqrt(sum((xyz-rand(1,3)).^2,2));
TZ=[ -0.0225
-0.0226
-0.0233
-0.0185
-0.0188
-0.0144
-0.0144
-0.0141
-0.0062
-0.0064
0
0
0
-0.0209
-0.0216
-0.0126
-0.0123
0
0
-0.0137];
Stress = abs(TZ);
StressNorm = (Stress-min(Stress))/(max(Stress)-min(Stress));
close all
figure
clmap = jet;
StressColor = interp1(linspace(0,1,size(clmap,1)),clmap,StressNorm,'nearest','extrap');
patch('Faces',F,'Vertices',xyz,'FaceVertexCData',StressColor,'FaceColor','interp');
hold on
%scatter3(xyz(:,1),xyz(:,2),xyz(:,3));
set(gca,'Xtick',[],'Ytick',[],'Ztick',[])
for k=1:size(xyz,1)
text(xyz(k,1),xyz(k,2),xyz(k,3),num2str(k));
end
xlabel('x');
ylabel('y');
zlabel('z');
view(3)
axis('equal');
##### 1 CommentShowHide None
alize beemiel on 13 Nov 2020
oh
thank you
thank you so much

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