Set value to jquery widget slider

EDIT: Simpler explenation of the problem first. More detailed explanation below.

I use some jquery widgets code to create a UI slider. The code is here:

https://webgl2fundamentals.org/webgl/resources/jquery-gman-circle.js

This can be used, calling the component directly in the JS script like this:

$("#rotation").gmanUnitCircle({
    width: 200,
    height: 200,
    value: 0,
    slide: function(e, u) {
      rotation[0] = u.x;
      rotation[1] = u.y;
      drawScene();
    },
  });

What I want to do is set a value to the slider with code. This seems to be possible calling the drawCircle(ctx) function of the code, with the angle you want but I dont know how to call it because is part of a big JQuery function that calls itself and sets all slider callbacks in the element construction. (you can check that in code of the link above).

The question is how can I do this in a simple way, or how can I call or access the drawCircle(ctx) function from the outside (from my specific circle instance)?

(Coming from c# I would do this exposing the method I want to access from the outside with an interface)

Code used to create the slider and se how it works, with the possibility of code edition in the web itself can be found here:

https://webgl2fundamentals.org/webgl/lessons/webgl-2d-rotation.html

Edit: This semms to be possible but still not able to achieve it.

https://learn.jquery.com/jquery-ui/widget-factory/widget-method-invocation/

Accessing widget instance from outside widget

So I tried $('#rotation').gmanUnitCircle('drawCircle') after setting the rotation that I want and similar combinations code attempts but it doesnt worrk.

More detailed explanation: (You dont need to read this if the problem is already understood. I just explain more extensively the problem, how a similar one was solved and more attempts to solve it I tried)

This question comes as a continuation of this question:

Set value to slider directly

I have the very same problem updating the circle slider.

My problem is that I set the values of the circle with the mouse click and drag, but I cannot set the values directly. I want to set the rotation of the circle to a determined value.

The full code I am working with is here:

https://webgl2fundamentals.org/webgl/lessons/webgl-2d-rotation.html

I tried to create a function that updates the value, calling the updateValue function in:

https://webgl2fundamentals.org/webgl/resources/jquery-gman-circle.js

function updateSlider(slider, value) {slider.updateValue(value)}

But it is not a function present in the UI element funtionality as in the slider case.

I tried then to call the drawCircle(ctx) function that can be found as used in the code:

function drawCircle(ctx)

But it is inside the _create: function() { and I dont know how to call it for my circle.

I also considered extendin the funcionality of the cicle created to set a value with the setSlider value function, but I dont know how to vinculate my click button event with this function to update the value.

rotCircle = $('#rotation').gmanUnitCircle({
      width: 200,
      height: 200,
      value: 0,
      slide: (e, u) => {
        this.rotation[0] = u.x;
        this.rotation[1] = u.y;
        this.drawScene(shader);
      },
      setSliderValue: (e, u) => { // <- I would want to call this function to set the values I desire in u
        this.rotation[0] = u.x;
        this.rotation[1] = u.y;
        this.drawScene(shader);
      },
    });

I tried to trigger the event of the function I created trying to dispatch o trigger an event that calls the function, with no success:

https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/dispatchEvent

Moreover, try to call a function through a forced event call does not seem to a good approach. Also I tried to call it through a button click event, as actually the value to the slider should be set with a button.

To sum up, I just want to set the value of the circle rotation slider directly. I am not familar with the Javascript event approach so that is why I guess I find this harder that expected.

Thanks in advance

Solution

I had a closer look at your code and reduced it to the absolute minimum. It turns out you can supply the starting value of the angle simply by putting it into the empty options argument of the initiatior method: $("#example").gmanUnitCircle({value: -Math.PI/3});. In my example I chose the value of -60° in radians.

$(function(){
  var widget=$("#example").gmanUnitCircle({value: -Math.PI/3});
  function setval(w,val){w.empty().data("gmanUnitCircle",null).gmanUnitCircle({value:val});}

  $('input').on('input',function(ev){ setval(widget,ev.target.value*Math.PI/180); })
});

#ui { width: 200px;}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="https://code.jquery.com/ui/1.8.16/jquery-ui.min.js"></script>
<script src="https://webgl2fundamentals.org/webgl/resources/jquery.mousecapture.js"></script>
<script src="https://webgl2fundamentals.org/webgl/resources/jquery-gman-circle.js"></script>
<body>
<div class="description">
Drag Circle
<p><input type="text" placeholder="enter an angle (deg)"></p>
</div>
<div id="example"></div>

I now added a work-around: Whenever you enter a number in the input field the widget will simply be re-created! It is probably not what you were looking for but it does the job very well.