Distance joint in javasript confusion

[gudu0]

How do I…?

I want to add a distance joint between 2 objects using javascript.

What is the expected result

My objects should be linked together

What is the actual result

It’s giving me an error.
Full error is: tailParts[i].addDistanceJoint is not a function

Me explaining what I’ve tried and situation.

I’ve had issues sort of like this, so I tried giving an index to tailParts, because it is an array, and that is the state it’s in now. I tried removing the “tailParts.” but then it gives a different error saying addDistanceJoint is not defined. I don’t really understand the documentation on the javascript event blocks, or really I don’t think I’ve found much besides this, and that’s not very helpful for what I’ve been doing (or at least I haven’t found it to be.) I’ve looked at the wiki page for distance joint, and the GDevelop docs for distance joint (what I mostly use) as well as the github code for distance joint. I don’t know if I’m just missing something or what.

This code runs when a new instance of my obj_block2 is made, which happens when the player eats(collides) an apple. Any help appreciated!

Related screenshots

[Keith_1357]

I’m trying to remember things without trying them. First, I think you need getX() and getY().

x and y seems to be zero. IDK. I could be wrong.

Secondly, I think you need a reference to the physics behavior. The object doesn’t have addDistanceJoints(), It’s in the behavior.

https://wiki.gdevelop.io/gdevelop5/events/js-code/javascript-in-extensions/#get-an-object-behavior-in-javascript

Example

//Draggable behavior
//---------------------
const OBJ = runtimeScene.getObjects("NewSprite")[0];
/** @type {gdjs.DraggableRuntimeBehavior} */
const O =OBJ.getBehavior("Draggable").isDragged();

/

I’m not sure why you gave false for the variable parameter. That’s for saving the joint ID to a variable. I know when you use the action that it’s optional. IDK if the same is true in Javascript. You might need to reference a variable.

I would need to test it myself but I don’t have the time for it. That might not be the only issues but it’s a start.

[gudu0]

I’ll try using getX/Y, the reason I used just x and y is because in the objects that are logged into the console, it has a x and a y property.

(sorry for the tiny image, wanted to get the whole object in view. the x and y property’s are highlighted at the bottom)

I don’t understand what you mean with referencing the physics behavior, could you please explain more?

I did not give false as the joint Id variable, I just didn’t include it. The action for making a distance joint says that its default value is none. (bottom right)

If I do find later that I need to use it, I can probably just go back in and a place to store it.

Thank you for this help though! I hope swapping to getX/Y solves the error.

[gudu0]

Swapping to the getX() and Y didn’t fix the error, but they also didn’t break it further, I think.

[Keith_1357]

@gudu0

I don’t understand what you mean with referencing the physics behavior, could you please explain more

See my original reply with a link and an example. I can test it later but not now.

Here’s an example from a previous post.

const player = objects[0];
/** @type {gdjs.Physics2RuntimeBehavior} */
const physicsBehavior = player.getBehavior("Physics2");
physicsBehavior.applyForce(10,10, player.getX(),player.getY())

[Keith_1357]

OK. I finally had some free time. This works for me. I used 2 objects “NewSprite1” and “NewSprite2”. Both objects had the physics behavior.

I also used a scene variable named “JointID”. I kept getting errors if I omitted the last parameter.

You could also merge the last lines and omit the physicsBehavior object

[gudu0]

Thank you so much again! I was struggling to figure out what to do with getting behavior. Your example works for me which is amazing. I think I actually do need to store the JointID’s though, otherwise I think its applying joints every time it runs, every frame. Again thanks though!!

(what I ended up with so far, haven’t done joint id stuff)

const player = runtimeScene.getObjects("obj_block")[0]; 
let tailParts = runtimeScene.getInstancesOf("obj_block2")
let jointID = runtimeScene.getVariables().get("JointID");
const physicsBehavior = player.getBehavior("Physics2");

console.log(tailParts.length);
//for each item in tailParts
for (let i = 0; i < tailParts.length; i++) {   
    if (tailParts.length > 1) {
        if (tailParts[i + 1] != undefined){
            physicsBehavior.addDistanceJoint(tailParts[i].getX(), tailParts[i].getY(), tailParts[i + 1], tailParts[i + 1].getX(), tailParts[i + 1].getY(), 64, 0, 10, false, jointID);   
        }        
    } else {
        physicsBehavior.addDistanceJoint(player.getX(), player.getY(), tailParts[i], tailParts[i].getX(), tailParts[i].getY(), 64, 0, 10, false, jointID);
    }   
}