Help with patch in a for loop

Question

Jack Smillie 2021-2-25

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/756449-help-with-patch-in-a-for-loop

评论： Walter Roberson 2021-2-25

I'm having a problem with patch in a for loop where I want it to change the positions of each rectangle created from patch to mimic an object moving with velocity over a given timestep but its plotting every shapes instance instead and I'm not sure how to solve this. I've tried putting the function hold off in but it doesnt seem to work unless I've put it in the wrong place. However, I'm not sure it's suitable as I want to keep the previous plot of roadlines in. The bit of code that has the problem is at the bottom but I provided the rest of the code

nStarts=2;
nCarsPerStart=100;
time=100;
deltaT=1;
maxCarVelocity=10;
patchCarPosWithTimeStepX=NaN(4,nStarts*nCarsPerStart);
patchCarPosWithTimeStepY=NaN(4,nStarts*nCarsPerStart);
startX=[0; 4.5; 4.5; 0];
startY=[0.9 4.5; 0.9 4.5; 2.7 6.3; 2.7 6.3];
nStarts2=NaN(nStarts,(time/deltaT));
for n=1:1:nStarts
nStarts2(n,:)=(n:nStarts:nStarts*(time/deltaT));
end
carPosition=carCoords(nStarts,nCarsPerStart);
%--------------------------%
function [carPosition] = carCoords(nStarts,nCarsPerStart)
% Creates a matrix of car positions based on their starting locations
%   Creates a NaN matrix and each location( or a lane in the model) has a
%   set number of vehicles generated backwards from the start coord of 0.
%   This is a cumulative sum from a random integer between two values to replicate the
%   semi-random disribution of distance between cars on a road.
carPosition=NaN(nStarts*nCarsPerStart,nStarts);
for i=1:nStarts
carPosition((1:nCarsPerStart)+(i-1)*nCarsPerStart,i)=cumsum([0; randi([-14,-8],nCarsPerStart-1 ,1)]);
end
       
end
%-----------------------------------%
carProperties=intitalCarProperties(nStarts,nCarsPerStart,maxCarVelocity);
%------------------------------------%
function [carProperties] = intitalCarProperties(nStarts,nCarsPerStart,maxCarVelocity)
% Creates a matrix indicating each car's properties in the simulation.
%   Detailed explanation goes here
% Max car velocity = 30 m/s ~ to 60mph in UK
driverBehaviour=1; % 1 = Normal behaviour
typeOfVehicle=1; %1 = Car (Average 2D dimensions = 4.7m x 1.9m)
%Starting location = number to indicate which location from the number of%
%starts. E.g. 1st location = 1 and 2nd location = 2%
carProperties=zeros(nStarts*nCarsPerStart,4);
for i=1:nStarts*nCarsPerStart
    carProperties(:,1)=maxCarVelocity;
    carProperties(:,2)=driverBehaviour;
    carProperties(:,3)=typeOfVehicle;
    
end
end
%----------------------------%
carPosWithTimeStep=repmat(carPosition,1,time+1);
timeSteps = repmat(0:deltaT:time,nStarts,1);
timeSteps = timeSteps(1:end);
for i=1:1:nStarts*nCarsPerStart
    
    for k=nStarts+1:1:nStarts*(time+1)
        
        carPosWithTimeStep(i,k)=carPosWithTimeStep(i,k)+carProperties(i,1)*timeSteps(1,k);
      
    end
end
roadLength=1000;
figure('units','normalized','position',[0 0 1 1])
road=plot ([0,roadLength],[7.3,7.3],'k',[0,roadLength],[3.65,3.65],'k--',...
     [0,roadLength],[0,0],'k','linewidth', 1.5);
 axis equal
 
for t=1:1:time
    for q=1:1:nCarsPerStart*nStarts
        for d=1:1:nStarts*(t/deltaT)
           
        if carPosWithTimeStep(q,d)>=0
        patchCarPosWithTimeStepX(:,q)=startX+carPosWithTimeStep(q,d);
      
        else
            continue
        end
            for o=1:1:nStarts
            if find(any(d==nStarts2(o,:)))
            patchCarPosWithTimeStepY(:,q)=startY(:,o);
            else
                continue
            end
            end
        end
    end
patch('XData',patchCarPosWithTimeStepX,'YData',patchCarPosWithTimeStepY,'FaceColor','Red');
drawnow
end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2021-2-25

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/756449-help-with-patch-in-a-for-loop#answer_633424

Record the handle of each patch object generated, and store it with the tracking position information for each object.

At any one time, decide whether a given object is a new object or is an existing object that moved.

If it is a new object, call your function to create the patch, and record the handle.

If it is not a new object, update XData and YData coordinates of the existing patch object.

If an object stops being tracked, either delete its associated patch, or else turn it invisible and add it to a cache of already-created patches ready to be dispatched next time a new object is needed.

2 个评论
显示无隐藏无

Jack Smillie 2021-2-25

编辑：Jack Smillie 2021-2-25

Is there any documentation on stuff related to that or an example code I can decipher the method from? I'm not really familar with how I'd go about doing what you said

Walter Roberson 2021-2-25

在 MATLAB Online 中打开

if car_still_exists(q)
    if isvalid(car_patches(q))
        update_car_position(car_patches(q), patchCarPosWithTimeStepX(:,q), patchCarPosWithTimeStepY(:,q));
    else
        car_patches(q) = new_car_patch(patchCarPosWithTimeStepX(:,q), patchCarPosWithTimeStepY(:,q));
    end
else
    delete(car_patches(q))
end
function update_car_position(car_patch, X, Y)
   set(car_patch, 'XData', X, 'YData', Y);
end
function car_patch = new_car_patch(X, Y)
    car_patch = patch('XData', X, 'YData', Y, 'FaceColor', 'r')
end