---
title: Combining with Boolean operations
---

You can combine models using the <a href="/docs/api/modules/makerjs.model.html#combine">makerjs.model.combine</a> function, passing these parameters:

<ul>
    <li>first model to combine, we'll call it "modelA"</li>
    <li>second model to combine, we'll call it "modelB"</li>
    <li>boolean to include modelA's paths which are inside of modelB</li>
    <li>boolean to include modelA's paths which are outside of modelB</li>
    <li>boolean to include modelB's paths which are inside of modelA</li>
    <li>boolean to include modelB's paths which are outside of modelA</li>
</ul>

Each model must be a closed geometry, and should not be self-intersecting. The effect of the 4 boolean parameters is shown in these examples:

{% highlight javascript %}
//combine a rectangle and an oval, several ways

var makerjs = require('makerjs');
    
function example(origin) {
    this.models = {
        rect: new makerjs.models.Rectangle(100, 50),
        oval: makerjs.model.move(new makerjs.models.Oval(100, 50), [50, 25])
    };
    this.origin = origin;
}

var examples = {
    models: {
        x1: new example([0, 0]),
        x2: new example([200, 0]),
        x3: new example([400, 0]),
        x4: new example([500, 0])
    }
};

//save us some typing :)
var x = examples.models;

makerjs.model.combine(x.x2.models.rect, x.x2.models.oval, false, true, false, true);
makerjs.model.combine(x.x3.models.rect, x.x3.models.oval, false, true, true, false);
makerjs.model.combine(x.x4.models.rect, x.x4.models.oval, true, false, true, false);

var svg = makerjs.exporter.toSVG(examples);

document.write(svg);
{% endhighlight %}

<script>
    LiveDoc.evalLastCode();
</script>

<hr/>

Instead of remembering the boolean flag combinations, shortcuts are provided for:
<ul>
    <li><a href="/docs/api/modules/makerjs.model.html#combineintersection">makerjs.model.combineIntersection</a></li>
    <li><a href="/docs/api/modules/makerjs.model.html#combinesubtraction">makerjs.model.combineSubtraction</a></li>
    <li><a href="/docs/api/modules/makerjs.model.html#combineunion">makerjs.model.combineUnion</a></li>
</ul>

{% highlight javascript %}
//combine a rectangle and an oval, several ways

var makerjs = require('makerjs');

function example(origin) {
    this.models = {
        rect: new makerjs.models.Rectangle(100, 50),
        oval: makerjs.model.move(new makerjs.models.Oval(100, 50), [50, 25])
    };
    this.origin = origin;
}

var examples = {
    models: {
        x1: new example([0, 0]),
        x2: new example([200, 0]),
        x3: new example([400, 0]),
        x4: new example([500, 0])
    }
};

//save us some typing :)
var x = examples.models;

makerjs.model.combineUnion(x.x2.models.rect, x.x2.models.oval);
makerjs.model.combineSubtraction(x.x3.models.rect, x.x3.models.oval);
makerjs.model.combineIntersection(x.x4.models.rect, x.x4.models.oval);

var svg = makerjs.exporter.toSVG(examples);

document.write(svg);
{% endhighlight %}

<script>
    LiveDoc.evalLastCode();
</script>

Now it is apparent why we need a closed geometry - because we need to know what is considered the inside of a model.

<h4>Return value</h4>

These function will return a new model object with 2 child models, <b>"a"</b> and <b>"b"</b> which are aliases for the 2 models you passed in.