How to plot two moving robot in the same figure and change one of them transparency？

Hello guys ，i want plot two moving robot in the the figure and change on of them transparency.

but i don't know how to change just on of them transparency use the code

alpha(robot,0.2) %change robot transparency

and i just want to implement the effect like below

And i try to use the task and joint space trajectory example to implement the result

The code are below for the purpose change

axis([-.8 .8 -.8 .8 0 1.2]);
view(135,15)
for i=1:length(trajTimes)
    % Current time 
    tNow= trajTimes(i);
    % Interpolate simulated joint positions to get configuration at current time
    configNow = interp1(tJoint,stateJoint(:,1:numJoints),tNow);
    configNow1 = interp1(tJoint,stateJoint(:,1:numJoints),tNow+1);
    poseNow = getTransform(robot,configNow,endEffector);
    show(robot,configNow1,'PreservePlot',false,'Frames','off');
    hold on
    show(robot,configNow,'PreservePlot',false,'Frames','off');
    jointSpaceMarker = plot3(poseNow(1,4),poseNow(2,4),poseNow(3,4),'r.-','MarkerSize',2);
%     alpha(robot,0.2)% here didn't works
    alpha 0.2
    drawnow limitrate ;
 end

but only one moveing like below picture shows

Can someone help me

Best wishes，

-jian

Answer 1

[Karsh Tharyani]

Hi Jian,

I hope this snippet helps.

% Create two instances of a rigid body tree since we want two visuals
rbt=loadrobot("kinovagen3",DataFormat="row");
copyrbt=copy(rbt);

% Some random configurations 
q0=homeConfiguration(rbt);
q1=randomConfiguration(rbt);
q2=randomConfiguration(rbt);

% Generate a trajectory to the random configurations
tpts=[0,1];
tquery=tpts(1):0.01:tpts(end);
traj1=quinticpolytraj([q0',q1'],tpts,tquery)';
traj2=quinticpolytraj([q0',q2'],tpts,tquery)';

% Find the patches which have a display name of '_mesh', and set their
% alpha values.
ax=show(rbt,traj1(1,:),PreservePlot=false,FastUpdate=true);
rbtpatches=findobj(ax.Children,'Type','patch','-regexp','DisplayName','_mesh');
set(rbtpatches,'FaceAlpha',0.2);

% Now visualize another instance of the same robot
hold on;
show(copyrbt,traj2(1,:),PreservePlot=false,FastUpdate=true,Parent=ax);

% This call will also find the previous patches. Hence we need to remove
% previously found patches from this query.
patchesnew=findobj(ax.Children,'Type','patch','-regexp','DisplayName','_mesh');
copyrbtpatches=patchesnew(~ismember(patchesnew,rbtpatches));

% You can also change the color aside from alpha
set(copyrbtpatches,'FaceAlpha',0.7);
set(copyrbtpatches,'FaceColor',[1,0,0]);

%% Visualize
rc=rateControl(50);
for i=1:size(tquery,2)
    show(rbt,traj1(i,:),PreservePlot=false,FastUpdate=true);
    show(copyrbt,traj2(i,:),PreservePlot=false,FastUpdate=true,Parent=ax);
    waitfor(rc);
end
hold off;

Best,

Karsh

[snow John]

Hi Karsh，

Thanks very much for your kindness help ，The source code are really help a lot. I do want to implement these kind of result，this kinds of visualization is very attractive for representation use.

Thanks agian

Best ,

-Jian