How to add changing member colors indicating the changing forces within the various members to this animation

Anyone know how to add code that basically changes the colour of each member according to which is in compression and tension. so red vs blue?

function lorry =Lorry_plot
figure
view(3)
grid on
axis ('equal');
% lorry
vertices_lorry = [0 1 0.5 ; 4 1 0.5; 6.5 1 0.5; 6.5 1 1.2; 6 1 1.3;...
    5 1 1.8; 4 1 1.8; 4 1 2; 0 1 2; ... % postive y of lorry
    0 -1 0.5; 4 -1 0.5; 6.5 -1 0.5; 6.5 -1 1.2; 6 -1 1.3;...
    5 -1 1.8; 4 -1 1.8; 4 -1 2; 0 -1 2]; % negative y of lorry
faces_lorry_cargo = [10 1 9 18; 1 2 8 9; 8 9 18 17; 10 11 17 18;...
    7 8 17 16; 1 2 11 10];
faces_lorry_driver = [7 6 15 16 16 16; 5 6 15 14 14 14; 5 4 13 14 14 14;...
    3 4 13 12 12 12; 2 3 4 5 6 7; 11 12 13 14 15 16; 2 3 12 11 11 11];
lorry(1)=patch('Faces',faces_lorry_cargo,'Vertices',vertices_lorry,'FaceColor',...
    [1 1 0],'EdgeColor','k'); 
lorry(2)=patch('Faces',faces_lorry_driver,'Vertices',vertices_lorry,'FaceColor',...
    [0.8 0.8 0.8],'EdgeColor','k');
% wheels
t = linspace(pi,2*pi,8)';
[a,b] = pol2cart(t,0.5); % create data for circle
v0 = a*0;
X = [v0 a a v0];
Z = [v0 b b v0];
Y = [v0-1 v0-1 v0+1 v0+1]*0.15;  
hold on
lorry(3)=surf(X+1,Y+.85,Z+.5,'facecolor',[0 0 0]); % draw wheel rear left
lorry(4)=surf(X+1,Y-.85,Z+.5,'facecolor',[0 0 0]); % draw wheel rear right
lorry(5)=surf(X+3.97,Y+.85,Z+.5,'facecolor',[0 0 0]); % draw wheel front left
lorry(6)=surf(X+3.97,Y-.85,Z+.5,'facecolor',[0 0 0]); % draw wheel front right
hold off
% truss
vertices_truss = [0 2.25 0; 4.5 2.25 0; 9 2.25 0; 13.5 2.25 0; 18 2.25 0; 22.5 2.25 0; 27 2.25 0;...
    22.5 2.25 4.5; 18 2.25 4.5; 13.5 2.25 4.5; 9 2.25 4.5; 4.5 2.25 4.5;... % pink truss positive y
    0 -2.25 0; 4.5 -2.25 0; 9 -2.25 0; 13.5 -2.25 0; 18 -2.25 0; 22.5 -2.25 0; 27 -2.25 0;...
    22.5 -2.25 4.5; 18 -2.25 4.5; 13.5 -2.25 4.5; 9 -2.25 4.5; 4.5 -3.25 4.5]; % blue truss negative y
faces_truss = [1 2;2 3;3 4;4 5;5 6;6 7;7 8;8 9;9 10;10 11;11 12;12 1;12 2;12 3;...
    11 3;11 4;10 4;9 4;9 5;8 5;8 6;... %pink side
    13 14;14 15;15 16;16 17;17 18;18 19;19 20;20 21;21 22;22 23;23 24;...
    24 13;24 14;24 15;23 15;23 16;22 16;21 16;21 17;20 17;20 18;... %blue side
    1 13;2 14;3 15;4 16;5 17;6 18;7 19;8 20;9 21;10 22;11 23;12 24]; %transverse
patch('Faces',faces_truss,'Vertices',vertices_truss,'FaceAlpha',0);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
                                        %CODE TO DRIVE STARTS HERE%
                                        
                                        
% What is the final position of the front
% of the lorry along the x-axis?
maxX = 30;
% How far should the lorry travel on each frame/loop?
% For faster velocity, use higher value. 
stepSize = 0.05;
% Advance the lorry in steps of "stepSize" until
% the front of the lorry reaches "maxX". 
arrived = false;
while ~arrived
    lorry(1).Vertices(:,1) = lorry(1).Vertices(:,1) + stepSize;
    lorry(2).Vertices(:,1) = lorry(2).Vertices(:,1) + stepSize;
    lorry(3).XData = lorry(3).XData + stepSize;
    lorry(4).XData = lorry(4).XData + stepSize;
    lorry(5).XData = lorry(5).XData + stepSize;
    lorry(6).XData = lorry(6).XData + stepSize;
    
    drawnow()
    
    % use pause() to slow the velocity
    pause(0) 
    
    % Determine if the next step would overshoot target
    arrived = max(lorry(2).Vertices(:,1)) + stepSize > maxX;
end
end 

[Jan]

Please narrow down, what you want to change. It is not efficient, when the readers have to understand your code before they try to guess, where you want to change what.

pause(0) does not slow down anything.

Please use the tools on top of the edit field to format your code.

[Rik]

I recovered the removed content from the Google cache (something which anyone can do). Editing away your question is very rude. Someone spent time reading your question, understanding your issue, figuring out the solution, and writing an answer. Now you repay that kindness by ensuring that the next person with a similar question can't benefit from this answer.

[darova]

Thanks @Rik

Answer 1

[darova]

What about this?

clc,clear
n = 20;
r = linspace(1.5,5,20);         % radius for curves animation
x = linspace(-1,1,n);           % x coordinate
x(end+1) = nan;                 % make end point as NaN to remove last edge
y = sqrt(r(1)^2-x.^2);
cmap = flip(jet(n));            % create colormap
maxd = max(y)-min(y)            % max difference height
cla
h = patch(x,-y+min(y),...
        'edgecolor','interp',...
        'linewidth',3);
        
ylim([-1 1]/2)

for i = 1:length(r)
    y = sqrt(r(i)^2-x.^2);
    ind = round((y-min(y))./maxd*(n-1)+1);  % indices of colors
    ind(end) = 1;
    c = cmap(ind,:);                        % get colors
    set(h,'xdata',x,'ydata',-y+min(y))
    set(h,'facevertexcdata',c)
    pause(0.5)
end

[latenfe]

There seems to be an error when this is run

Error using patch
Not enough input arguments.

Error in patch_lorry (line 87)
h = patch(x,-y+min(y),...

[darova]

Maybe it wants Z coord. Try this

h = patch(x,-y+min(y),x*0,...
        'edgecolor','interp',...
        'linewidth',3);

[latenfe]

it shows once it has completed the path

Error using matlab.graphics.primitive.Patch/set
Invalid or deleted object.

Error in patch_lorry (line 97)
    set(h,'xdata',x,'ydata',-y+min(y))
 
>> 

>>

[darova]

Maybe you have h variable? What do you see if you type

get(h)

[latenfe]

i get

Unrecognized function or variable 'h'.
 

[latenfe]

heres the full code for reference

function lorry =patch_lorry
%lorry= patch_lorry
%animates the movement of the lorry across the bridge
% Version 2: created 15/03/21. Author: F.Olorunniwo

figure
view(3)
grid on
axis ('equal');
% lorry
vertices_lorry = [0 1 0.5 ; 4 1 0.5; 6.5 1 0.5; 6.5 1 1.2; 6 1 1.3;...
    5 1 1.8; 4 1 1.8; 4 1 2; 0 1 2; ... % postive y of lorry
    0 -1 0.5; 4 -1 0.5; 6.5 -1 0.5; 6.5 -1 1.2; 6 -1 1.3;...
    5 -1 1.8; 4 -1 1.8; 4 -1 2; 0 -1 2]; % negative y of lorry
faces_lorry_cargo = [10 1 9 18; 1 2 8 9; 8 9 18 17; 10 11 17 18;...
    7 8 17 16; 1 2 11 10];
faces_lorry_driver = [7 6 15 16 16 16; 5 6 15 14 14 14; 5 4 13 14 14 14;...
    3 4 13 12 12 12; 2 3 4 5 6 7; 11 12 13 14 15 16; 2 3 12 11 11 11];
lorry(1)=patch('Faces',faces_lorry_cargo,'Vertices',vertices_lorry,'FaceColor',...
    [1 1 0],'EdgeColor','k'); 
lorry(2)=patch('Faces',faces_lorry_driver,'Vertices',vertices_lorry,'FaceColor',...
    [0.8 0.8 0.8],'EdgeColor','k');
% wheels
t = linspace(pi,2*pi,8)';
[a,b] = pol2cart(t,0.5); % create data for circle
v0 = a*0;
X = [v0 a a v0];
Z = [v0 b b v0];
Y = [v0-1 v0-1 v0+1 v0+1]*0.15;  
hold on
lorry(3)=surf(X+1,Y+.85,Z+.5,'facecolor',[0 0 0]); % draw wheel rear left
lorry(4)=surf(X+1,Y-.85,Z+.5,'facecolor',[0 0 0]); % draw wheel rear right
lorry(5)=surf(X+3.97,Y+.85,Z+.5,'facecolor',[0 0 0]); % draw wheel front left
lorry(6)=surf(X+3.97,Y-.85,Z+.5,'facecolor',[0 0 0]); % draw wheel front right
hold off
% truss
vertices_truss = [0 2.25 0; 4.5 2.25 0; 9 2.25 0; 13.5 2.25 0; 18 2.25 0; 22.5 2.25 0; 27 2.25 0;...
    22.5 2.25 4.5; 18 2.25 4.5; 13.5 2.25 4.5; 9 2.25 4.5; 4.5 2.25 4.5;... % pink truss positive y
    0 -2.25 0; 4.5 -2.25 0; 9 -2.25 0; 13.5 -2.25 0; 18 -2.25 0; 22.5 -2.25 0; 27 -2.25 0;...
    22.5 -2.25 4.5; 18 -2.25 4.5; 13.5 -2.25 4.5; 9 -2.25 4.5; 4.5 -3.25 4.5]; % blue truss negative y
faces_truss = [1 2;2 3;3 4;4 5;5 6;6 7;7 8;8 9;9 10;10 11;11 12;12 1;12 2;12 3;...
    11 3;11 4;10 4;9 4;9 5;8 5;8 6;... %pink side
    13 14;14 15;15 16;16 17;17 18;18 19;19 20;20 21;21 22;22 23;23 24;...
    24 13;24 14;24 15;23 15;23 16;22 16;21 16;21 17;20 17;20 18;... %blue side
    1 13;2 14;3 15;4 16;5 17;6 18;7 19;8 20;9 21;10 22;11 23;12 24]; %transverse
patch('Faces',faces_truss,'Vertices',vertices_truss,'FaceAlpha',0);
%changing members 

n = 20;
r = linspace(1.5,5,20);         % radius for curves animation
x = linspace(-1,1,n);           % x coordinate
x(end+1) = nan;                 % make end point as NaN to remove last edge
y = sqrt(r(1)^2-x.^2);
cmap = flip(jet(n));            % create colormap
maxd = max(y)-min(y);            % max difference height
h = patch(x,-y+min(y),x*0,...
        'edgecolor','interp',...
        'linewidth',3);
        
ylim([-1 1]/2)
for i = 1:length(r)
    y = sqrt(r(i)^2-x.^2);
    ind = round((y-min(y))./maxd*(n-1)+1);  % indices of colors
    ind(end) = 1;
    c = cmap(ind,:);                        % get colors
    set(h,'xdata',x,'ydata',-y+min(y))
    set(h,'facevertexcdata',c)
    pause(0.5)
end 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
                                        %CODE TO DRIVE STARTS HERE%
                                        
                                        
% What is the final position of the front
% of the lorry along the x-axis?
maxX = 30;
% How far should the lorry travel on each frame/loop?
% For faster velocity, use higher value. 
stepSize = 0.05;
% Advance the lorry in steps of "stepSize" until
% the front of the lorry reaches "maxX". 
arrived = false;
while ~arrived
    lorry(1).Vertices(:,1) = lorry(1).Vertices(:,1) + stepSize;
    lorry(2).Vertices(:,1) = lorry(2).Vertices(:,1) + stepSize;
    lorry(3).XData = lorry(3).XData + stepSize;
    lorry(4).XData = lorry(4).XData + stepSize;
    lorry(5).XData = lorry(5).XData + stepSize;
    lorry(6).XData = lorry(6).XData + stepSize;
    
    drawnow()
    
    % use pause() to slow the velocity
    pause(0) 
    
    % Determine if the next step would overshoot target
    arrived = max(lorry(2).Vertices(:,1)) + stepSize > maxX;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

end 

end

and the output 

[darova]

THe code i wrote is not a part of your code. It's just simple example. Run it separately and see how it works

Ask if needed

[latenfe]

is there a way to make the members of my truss in the simulation blue/red

[darova]

Im sure its possible. Can you ask somethins specific?