Turn a point's visibility on and off dynamically

[Marcelo Rodrigues]

Hello everybody,

Please, I would like to ask for help on the following question:

1- Define a random variable in Moodle -> w = shuffle([0,1]);

2- Define the point in jsxgraph: 

var interof1 = b.create('intersection', [l1, l6, 0],{name:'O2', size:3,fixed:true, Color:'#ff0000', visible:{ if w[0]==0, true, false}});

3- My objective is that if w[0]==0 the point "interof1" is visible and if w[0]==1 the point is not visible.

4- I tried to apply the code to the visible property: visible:{if w[0]==0, true,
    false}}); - but it did not work.

5- Is there any way to do this?

Thank you very much, Marcelo.

[古今中外数学网]

I am a old style one, so not sure your code style.

but it should work, if you put code as below:

visible: function(){return (w[0]==0?true:false)}

[Marcelo Rodrigues]

Hello,

Thank you very much for your feedback and explanations! Thank you very much!

I created a new point as below:

var p100 = b.create('point',[20,20],{size:4, visible: function(){return (w[0]==0?true:false)}});

and I applied the function you sent me.

However, the point is always visible, even if w[0] varies between 0 and 1.

The p100 point visibility turn-off did not work.

I'm checking to see if I made a mistake...

Marcelo.

[古今中外数学网]

you may need add board.update(); as last line in your code, to update board.

[Marcelo Rodrigues]

Hello,

Thank you very much for your feedback!

I put the code you sent me, but it didn't work.

The created point "p100" always remains visible, even with w[0] varying between 0 and 1.

Marcelo.

[Alfred Wassermann]

Dear all,

here is an example which uses two types of random variables. w[0] is randomly set on load, w[1] is set to random value at every update.

-----------------------

const board = JXG.JSXGraph.initBoard('jxgbox', {
    boundingbox: [-5, 5, 5, -5], axis:true
});

var w = [0, 0];

var p0 = board.create('point', [2, -3], {name:'drag me', color:'blue'});

// Static version:
// Set w[0] once:
w[0] = Math.round(Math.random());
// Create the point with fixed visibility
var p100 = board.create('point',[2,2], {
    size:4,
    visible: w[0]==0?true:false
});

// Dynamic version:
// Set w[0] once:
w[1] = function() { return (Math.round(Math.random())==0?true:false); };
// Create the point with fixed visibility
var p200 = board.create('point',[2,-2], {
    size:4,
    visible: w[1]
});

-----------------------

See it live at https://jsfiddle.net/v1n20w3c/. In your case, it might be helpful to print the value of w[0] to the console, i.e.

     console.log(w[0]);

to see what it contains.

Best wishes,

Alfred

[Marcelo Rodrigues]

Dear Alfred,

Thank you very much for your support and help!

I am analyzing the behavior of the programming you made, as I want to use it in an exercise for students in the Moodle environment.

I was in doubt, after the students answered the quiz, if the answer they originally gave would remain the same or if it would "change" each time the question was accessed.

Thank you very much! Marcelo.

Não contém vírus.www.avg.com

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