3D Emitter Script

Hey, happy to hear this is useful to someone. I never got around to making the video, but if you need any help getting it set up or navigating the different settings or API, I'd be happy to answer any questions you might have.

Hey eL,

Glad you found it useful (kinda).

1) There's no built-in way to trigger a set number of particles, but there might be a way to do it if you're down to do some custom scripting. I can walk you through it if that sounds like something you want to try.

2) I didn't add in parent scaling compensation, so the scaling of the emitter needs to be uniform (preferably 1,1,1). I would suggest making it a sibling of the toaster object, rather than a child, assuming the toaster's parent object (and all parents above that) has/have uniform scale.

- Ryan

In the Emitter.js script, you'll find the emit function around line 138. I would add a second parameter to the function (e.g. "num"). After line 141, add a line adding this number to the "newObjects" variable. Should look something like this:

function emit(now, num = 0) {
    // calculate how many new objects to make
    var newObjects = valueWithVariance(script.api.birthrate)*script.api.timeSinceLastUpdate;
    newObjects = Math.floor(newObjects) + ((Math.random() < (newObjects % 1)) ? 1: 0); // decimal portion becomes probability for adding an extra object
    newObjects += num;
    ...

Note: Not sure how familiar you are with more-than-basic JS syntax, but I set "num" to have a default value of 0, so if you don't pass a second parameter to the function, the script still works as usual

Now, for connecting the touch gesture, you can either code directly in Emitter.js (if the the user can tap anywhere on screen), or you can add it separately (if it's tied to some kind of UI element).

If directly in Emitter.js:

At the bottom of the script, create a TapEvent and bind a function to it that calls the emit function, like so:

var onTap = script.createEvent('TapEvent');
onTap.bind(function() {
    emit(Date.now(), 1);
});

This will emit 1 object when the user taps anywhere on the screen

If in a separate script:

First, in Emitter.js, add a line that exposes the emit function on the script api:

script.api.emit = emit;

Then, in a separate script, you'll need to create an input for the Emitter script so you can access that api:

// @input Component.ScriptComponent emitScript

script.emitScript.api.emit(Date.now(), 1);

Add this script to your UI element and set it to initialize on tap and then make sure to link the Emitter.js script to the input.

In either case, you'll want to set the birthrate of the Emitter.js script UI to 0 to make sure it doesn't emit any unwanted objects. And I think that should do it. I didn't test any of that though, so let me know if you run into any issues and I'll help you debug.

Sidenote: if you're relatively comfortable with JavaScript, it might be better just to use Cannon.js to simulate physics. It's way better than my super simplified physics engine and will give you more control over the behavior of your objects, including collisions between them, which is cool. I was actually considering implementing it myself for an advanced version of the script, but never got around to it. You do however lose the nice UI interface though, so if you're not into scripting, beyond the basics I outlined above, you can ignore this.