Plotting a circle on top of a trisurf graph.

I have solved a finite element problem, and I am using trisurf to plot the result. However, I want to specify a circular patch centered at [-0.3, -0.2] with radius 0.12, which is an area that contains activity i want to track.

T_delaunay is the triagularization of the whole nodal point V of size 2923 nodes.

T_delaunay = delaunay(V(1,:)',V(2,:)');

T_delaunay = delaunay(V(1,:)',V(2,:)');
T0 = delaunay(V(1,c_nodes)', V(2,c_nodes)');

centers = [-0.3 -0.2]; radii = 0.12;
for i = 1:length(time)

    [U1,U2,~,~] = unpack(u_sol(i,:)', N);
    
    phi1_Glc = T(17)*(U1.Glc./(U1.Glc + M(17))); % Glucose

    bux = U1.oxy;
    Cfree = NaN*zeros(1);
    
    for j = 1:length(bux)
        Cfree(j) = XTotalToFree(bux(j));
    end
    
    phi1_O2 = lambda(21)*((Cfree' - U2.oxy).^k); % Oxygen

    phi2_Glc = T(18)*(U2.Glc./(U2.Glc + M(18)));

    Ogi = (phi1_O2)./(phi1_Glc - phi2_Glc);
    
    ind = 0.001*(5.3811 -  4.8971); % protocol 2
    axis_min = 4.8971 + ind;
    axis_max = 5.3811- ind;

    trisurf(T_delaunay,V(1,:),V(2,:),Ogi,'EdgeColor','none')
    hold on
%     trisurf(T0, V(1,c_nodes), V(2,c_nodes), Ogi(c_nodes),'EdgeColor','k', 'Linewidth',1)
    caxis([axis_min, axis_max])
    view(2)
%     viscircles(centers,radii,'Color','k');
    hold off
    axis('square')
    title (sprintf('OGI for Protocol %d at time = %g min', Protocol, time(i) ))
    set(gca,'FontSize',12)
    colorbar
    pause(1)
end

I have used the explanation given here: https://www.mathworks.com/matlabcentral/answers/98665-how-do-i-plot-a-circle-with-a-given-radius-and-center#answer_108013

However, the circular patch will not show. Here is the result.

I also tried to create a delaunay triangularization of the 41 nodes contained within the patch. I specify that as T0.

T0 = delaunay(V(1,c_nodes)', V(2,c_nodes)');

I get a result which shows the triangles. However, I do not want the triangles to show. All i want to see is the boundary of the circle of the patch.

I will appreciate any help I can get.

Thanks.

Answer 1

[Voss]

It may be that the circle is beneath the surface object. I mean, I would expect the circle's 'ZData' to be all zeros - the default - which is obviously less than the 'ZData' of the surface created by trisurf. (I don't have access to viscircles to investigate.) If this is what's going on, one way to correct it is to set the axes 'SortMethod' property to 'childorder'.

[Gideon Idumah]

Thank you @Benjamin that surely worked. I set the 'SortMethod' property to 'childorder' and I was able to see the circles using viscircles.

Thank you once again.