Plot disappears when trying to interpolate

Good afternoon,

In the code below for some weird reason i cant figure out how to interpolate the color so it changes as it extends away from (0,0,0), could you possibly tell me how I would be able to fix this?

clc; clear; close all;

i = 1;
PStress = zeros(134343,3);


Yieldstr = 1000; %KPa 


minValue = -4*Yieldstr;
maxValue = 4*Yieldstr;
fidelity = Yieldstr/8; %We can adjust this to make cleaner graphs, might just take longer to run

for sigx = minValue:fidelity:maxValue
    for sigy = minValue:fidelity:maxValue
        for sigz = minValue:fidelity:maxValue
            
            %Reduced to sig1-3
            VM = (1/(sqrt(2)) * sqrt((sigx-sigy).^2 + (sigy-sigz).^2 +(sigz-sigx).^2));
            
            if VM < Yieldstr
                if (sigx==sigy) && (sigy==sigz) && (sigz==sigx)
                %stops code
            else
                PStress(i,1) = sigx;
                PStress(i,2) = sigy;
                PStress(i,3) = sigz;
                
                i = i + 1;
                
                end
            end
        end
    end
end

Data = sqrt(sigx.^2+sigy.^2+sigz.^2);
colormap cool
shading interp

D = alphaShape(PStress,inf);

Warning: Duplicate data points have been detected and removed.

plot(D,"FaceColor","none","EdgeColor","interp");

Warning: Error creating or updating Patch
Error in value of property FaceVertexCData
Number of colors must equal number of vertices

If you remove the edge color part you will see the plot comes back to its original shape. The goal is to have something that looks like this,

Thanks for the time as always,

Kevin

Answer 1

[Adam Danz]

Plotting an alphaShape creates a patch object. When set to interp, the EdgeColor property requires existing CData or FaceVertexData prior to setting EdgeColor (see documentation). From your description, the interpolation should be based on distance to (0,0,0) so I've set CData to the distance of each vertex from (0,0,0).

i = 1;
PStress = zeros(134343,3);

Yieldstr = 1000; %KPa

minValue = -4*Yieldstr;
maxValue = 4*Yieldstr;
fidelity = Yieldstr/8; %We can adjust this to make cleaner graphs, might just take longer to run

for sigx = minValue:fidelity:maxValue
    for sigy = minValue:fidelity:maxValue
        for sigz = minValue:fidelity:maxValue
            
            %Reduced to sig1-3
            VM = (1/(sqrt(2)) * sqrt((sigx-sigy).^2 + (sigy-sigz).^2 +(sigz-sigx).^2));
            
            if VM < Yieldstr
                if (sigx==sigy) && (sigy==sigz) && (sigz==sigx)
                    %stops code
                else
                    PStress(i,1) = sigx;
                    PStress(i,2) = sigy;
                    PStress(i,3) = sigz;
                    
                    i = i + 1;
                    
                end
            end
        end
    end
end

Data = sqrt(sigx.^2+sigy.^2+sigz.^2);
colormap cool
shading interp

D = alphaShape(PStress,inf);

Warning: Duplicate data points have been detected and removed.

h = plot(D, 'FaceColor', 'none');
distance = sqrt(sum(h.Vertices,2).^2);
h.CData = distance;
h.EdgeColor = 'interp';
cb = colorbar();
ylabel(cb, 'Distance');
xline(0, 'k:')
yline(0, 'k:')

[Kevin Hanekom]

This is amazing, thank you for solving this for me! so much to learn, exciting.