so I'm making a videogame

I have a vector of enemy handles so that I can assign visibility to certain enemies and not others, but once I update all of their positions (xdata and ydata), the visibility gets messed up and all become visible in the entire map. Anyone know why? I tried to use get(e,'visible') but it returns a cell of 'on' or 'off' that sucks to feed into set

Answer 1

[Stephen]

            y=get(h,'ydata');
            x=get(h,'xdata');
            hy = hypot(ye-y,xe-x)<8;
            set(e(hy),'visible','on')

this gets the player position and makes certain enemies visible

xs=sign(xe-x)*randint;
ys=sign(ye-y)*randint;
hy = hypot(ye-y,xe-x)<6;
hy = logical(hy.*(loc==zones(y,x)));

xe(hy)=xe(hy)-xs(hy);
ye(hy)=ye(hy)-ys(hy);
set(e,'xdata',xe,'ydata',ye)

This updates the enemies position and ruins everything

Answer 2

[Matt Kindig]

Do you have any calls to 'drawnow'? I don't think that simply changing the xdata/ydata is supposed to change handle visibility. Some other commands, such as 'figure', 'pause', and others automatically call drawnow.

One way you could quickly set all visibilities is to pass in a vector of handles to the set command. Something like:

set( HandlesOfHiddenObjects, 'Visible', 'off');
set( HandlesOfVisibleObjects, 'Visible', 'on');

[Walter Roberson]

drawnow() should not affect the visibility of anything.

[Stephen]

I have drawnow in the main while loop of the game

Answer 3

[Walter Roberson]

You cannot set the visibility of individual points in a line object. Your visibility with that code is going to be set according to the last value that happens to be in the array.

[Stephen]

it isn't one line object, but several single point objects whose handles I packed into a single vector, e. I'll try some different syntax

[Stephen]

also, the visibility line works, it's just that once I update the positions it resets all visibilities