Spawn only one object with AR

Help & Support
1

this is the project i forked

https://playcanvas.com/editor/project/774862

In this project you are spawning some plants (as many as you give the screen).

I would like to know if there is any way to spawn only one object and disable the option to put more objects.

Thank you very much and greetings to all. (sorry for my english which is not very good)

2

Hi @RafaelLopera,

That’s definitely doable, there is a number of ways you can do that change.

The easiest way looking at the hit-test.js script is to update the pointerUpdated property only once, that will have the effect of placing only a single object in the lifetime of the application.

// update line 30 to:
if(self.pointerUpdated === 0){
   self.pointerUpdated = 1;
}
3

Captura
Captura938×767 68.7 KB

update line 30 as you told me, but I keep putting objects when I press click,

4

Ah right, I see that counter is being reset at the bottom of the script. Nevermind I’ve updated your script to included a maxCount property, set it to whatever you like e.g. 1 to control the max number of spawn objects.

var HitTest = pc.createScript('hitTest');

HitTest.attributes.add('object', { type: 'asset', assetType: 'template' });
HitTest.attributes.add('pointer', { type: 'entity' });
HitTest.attributes.add('maxCount', { type: 'number', default: 1, min: 0, });

// initialize code called once per entity
HitTest.prototype.initialize = function() {
    if (! this.app.xr.hitTest)
        return;
    
    var self = this;
    
    this.countCreated = 0;
    this.lastCreated = 0;
    this.pointerUpdated = 0;
    
    // when XR session is started
    this.app.xr.on('start', function() {
        // start hit test from viewer position (middle of the screen)
        this.app.xr.hitTest.start({
            spaceType: pc.XRSPACE_VIEWER,
            callback: function(err, hitTestSource) {
                // when hit test session started
                hitTestSource.on('result', function(position, rotation) {
                    // position and rotate pointer to hit point
                    self.pointer.setPosition(position);
                    self.pointer.setRotation(rotation);
                    // enable pointer
                    self.pointer.enabled = true;
                    // set pointer state to 1
                    self.pointerUpdated = 1;
                    
                    self.app.fire('hitTestAvailable');
                });
            }
        });
    });
};

HitTest.prototype.update = function() {
    
    if( this.countCreated >= this.maxCount ) return;
    
    // if pointer been updated
    if (this.pointerUpdated === 1) {
        // set pointer state to 2, which will hide pointer next frame
        this.pointerUpdated = 2;
        
        // if user taps on screen (input source is available)
        if (this.app.xr.input.inputSources.length) {
            var now = Date.now();
            // every 200 milliseconds
            if ((now - this.lastCreated) > 200) {
                this.lastCreated = now;

                // clone object
                var ent = this.object.resource.instantiate();
                ent.enabled = true;

                // position on picked location
                ent.setPosition(this.pointer.getPosition());

                // rotate randomly
                ent.setEulerAngles(0, Math.random() * 360, 0);
                
                // scale a bit randomly
                ent.setLocalScale(Math.random() * 0.5 + 0.3, Math.random() * 0.3 + 0.3, Math.random() * 0.5 + 0.3);
                
                ent.reparent(this.app.scene.root);
                
                this.countCreated++;
            }
        }
    } else if (this.pointerUpdated === 2) {
        // if pointer state is 2, reset state
        this.pointerUpdated = 0;
        // and hide pointer
        this.pointer.enabled = false;
    }
};

After parsing the script in editor:

image

Tested on Chrome with the Mozilla WebXR emulator extension:

image
image1277×1182 138 KB

1 Like
5

Thank you very much, it works perfectly, now I will be implementing my things. All the best

1 Like